Willingness to accept risk; patients vs. clinicians
A study in tomorrow's British Journal of Obstetrics and Gyaecology has been receiving a lot of press. Unfortunately, the study is grossly underpowered, poorly conducted, and the authors misinterpret their own results. The study is
Vaginal delivery compared with elective caesarean section: the views of pregnant women and clinicians. The authors interviewed women expecting their first baby as well as a variety of clinicians (obstetricians, midwives, urogynecologists and colorectal surgeons). The authors claim to have found that patients and midwives were much more willing to tolerate risk of serious adverse outcomes than obstetricians, urogynecologists and colorectal surgeons.
The technical problems with the study are rather straightforward and call the validity of the results into question. There are very few participants in the study [Nulliparas (n = 122), midwives (n = 84), obstetricians (n = 166), urogynaecologists (n = 12) and colorectal surgeons (n = 79)], too few for any meaningful results. In addition, the recruitment process for pregnant women introduced bias into the sample; women who did not speak fluent English were barred from participating in the study, as were women who were obese, had underlying medical conditions, or pregnancy complications. Of 193 women who were approached for the study, 58 refused to participate and 30 additional women were subsequently excluded.
The authors introduced further bias providing their view of the complications of C-section:
A detailed explanation of caesarean section and its possible complications (major abdominal surgery, anaesthesia requirements, wound pain and need for more analgesia, decreased mobility, longer hospital stay, inability to drive for 6 weeks; increased risk of uterine, pelvic and bladder infection, wound breakdown, blood loss, transfusion, thrombosis; potential risks in future pregnancies, placenta accreta, uterine scar rupture; and neonatal respiratory problems with potential neonatal intensive care unit admission, jaundice, and temporary feeding difficulties)...
The authors do not reveal whether women were provided with information about the incidence of these complications, or merely told that they could occur.
The study participants were presented with a variety of complications of vaginal delivery, and asked to quantify the amount of risk they were willing to accept for each specific complication before they would abandon vaginal delivery in favor of elective C-section. Clinicians were asked the same questions, but were instructed to respond as if they or their partner were the pregnant patient. In virtually every category, both patients and midwives expressed a higher tolerance than obstetricians, urogynecologists and colorectal surgeons for accepting complications of vaginal delivery rather than choosing an elective C-section.
The authors offer this interpretation of their findings:
Our findings demonstrate that women are able to quantify the risks of VD they would be prepared to accept before they would request an elective caesarean section. Compared with clinicians, pregnant women tend to have a much higher threshold for the potential complications of VD, especially those associated with the pelvic floor. Anal incontinence was the potential complication with the lowest utility score for pregnant women. All groups ranked pelvic floor problems fourth of the top five reasons for preferring an elective caesarean section over VD. Pregnant women’s views more closely resembled those of midwives than those of other clinicians...
The caesarean section rate has risen in most developed countries over the past 10–15 years partially because of maternal request and lower thresholds among physicians
to perform the operation due to increasing levels of litigation. Florica et al. found an increase in caesarean section over a 5-year period to be due to suspected fetal distress, maternal request and labour dystocia. Our study demonstrates
that low-risk obstetric women are more accepting of many of the risks of VD than clinicians. However, when faced with the alternative choices of potential severe
complications either for themselves or for their baby from VD, many will preferentially choose delivery by caesarean section...
We have shown that both pregnant women and clinicians are able to quantify the different levels of potential risks (utility scores) they would be prepared to accept before requesting an elective caesarean section, while being aware of the potential complications of elective caesarean section.
Actually, they've shown nothing of the kind. First of all, the authors failed to include main complication that elective C-section is typically used to prevent: injury to the baby. They only looked at willingness to accept risk of specific maternal complications of vaginal delivery.
Secondly, and far more important, they showed that people with little or no experience of bad outcomes (women and midwives) were more willing to accept the risks of complications they had never seen than clinicians who were directly acquainted with those complications. That does not tell us anything about their tolerance of risk, it merely tells us about their understanding of risk.
This study reminds me of studies that compare teen driver and adult driver tolerance for risk during driving. According to studies like
Hazard and Risk Perception among Young Novice Drivers:
Research indicates that young drivers underestimate the risk of an accident in a variety of hazardous situations. At the same time, they overestimate their own driving skill. Young drivers are also more willing to accept risk while driving than experienced drivers.
The willingness of teenagers to accept risk tells us nothing about their willingness to accept poor outcomes, it only tells us that they do not have a mature understanding of the risks.
Similarly, this study does NOT indicate that women are more willing to accept the complications of vaginal delivery than clinicians. It tells us that women do not have any basis for understanding the risks. Unless and until the authors can demonstrate that women and midwives who do have experience with the specific complications are willing to accept those complications, they've told us nothing.
Labels: risk
Narcissism, confidence and risk
I am very intrigued by Alex's post about Fromm's theory of collective narcissism and homebirth advocacy. There are many aspects that sound very familiar to the claims and behavior of homebirth advocates.
The individual narcissist ... practices "magical thinking"--she is omnipotent, there is nothing she is not capable of if only she sets her mind to it."
" ... the narcissist makes choices based on bogus certainty. They are mired in self-deception, believe they already know all there is to know, and are unwilling to ask sincere questions or change their views in response to new sources of information."
In researching this topic further, I came across the article
Narcissism, Confidence and Risk Attitude in the Journal of Behavioral Decisionmaking, 2004:
In the simplest terms, one can think of narcissists as individuals for whom enhancing the positivity of the self (specifically, to achieve status and esteem) is overwhelmingly important... In the present research, we look at decision making as one of the domains of narcissists’ behavior that may be differentially distorted ... [W]e suspected that narcissists’ decisions may be undermined by their short-term interest in maintaining an inflated self-image. Narcissists’ grandiose self-views may preclude the realistic appraisal of one’s likelihood of success needed for successful decisions, resulting in overconfidence and risk-taking.
One aspect of homebirth advocates' narcissism is the claim of being "educated" about childbirth. Indeed, they may have done more reading and reflection than the average woman. However, the claims of "education" are absurd on their face when compared to the amount of relevant education of a doctor, nurse, or medical scientist. The narcissism of homebirth advocates precludes them from understanding the tremendous gulf between being an "educated" lay person and being actually educated on the topic of childbirth.
The claim of being "educated" is only the beginning of the homebirth advocate's over confidence and risk taking. The authors define overconfidence as: "an inflated subjective probability of a particular outcome occurring." There is nothing more emblematic of over confidence than the inane injuction to "trust" birth. There is nothing inherently trustworthy about birth, one of the leading killers of young women and children in every time, place and culture.
Regarding risk taking:
The second pitfall in narcissists' decision making may be their willingness to take risks. ... [W]hen coupled with overconfidence ... risk-taking systematically leads to losses ... What is the available evidence that narcissists take bigger risks than non-narcissists? ... They are focused on success and achievement, and display little conscious avoidance orientation or fear of failure. This greater focus on success could lead them to place bets on successful outcomes with less worry about poor performance. Also, there is empirical evidence for narcissists’ elevated reports of sensation-seeking. Research has also demonstrated a link between threatened self-esteem and risk-taking... To the extent that high self-esteem is reflected in narcissism, this result is consistent with the prediction that narcissists will display more risk-taking on tasks involving their own knowledge.
In other words, the inappropriate over confidence of homebirth advocates both in their self assessment of their own knowledge and in their beliefs about the trustworthiness of birth, lead them to minimize the risks of childbirth or to inappropriately believe that they are well prepared to manage those risks. What is truly striking, however, is the extent to which the self esteem of homebirth advocates is involved in the decision to choose homebirth. Those who choose homebirth are never humble about the choice. It is almost always accompanied by claims of knowing more or caring more. It is almost never presented as one possible choice among many, and more remarkably, the increased risk is virtually never acknowledged.
Labels: risk
Motives and risk perception
As I wrote in a previous post,
What does it mean to understand a risk?,lay people often don't understand risk. In large part, this is due to simple lack of knowledge about statistics. However, there are also important psychological motives involved, particularly when people appear to know the facts about risk but act in ways that demonstrate that they are ignoring what they know.
In
Motives, Health Risk Perception, and Decision-Making, Klein and Cerully seek to identify these motives. Their discussion of the desire for self-enhancement is particularly relevant to understanding the self congratulatory nature of homebirth advocacy.
An extensive literature suggests that most people desire to hold positive views of themselves on a wide variety of dimensions, and many of these views are distorted. The motive of self-enhancement can be seen in many places when one looks at health beliefs and decisions. People tend to be unrealistically optimistic about their chances of experiencing a wide variety of health events and view their own health behaviors as superior to those of their peers.
We certainly see that at work in homebirth advocacy. While some homebirth advocates have literally no idea of the risks that they are undertaking, others know that there is a risk, but don't believe that it could happen to them. Of note, homebirth advocates are uniformly convinced that their own health behaviors are superior to those of other women, when the evidence is precisely the opposite. Homebirth advocates are constantly prattling about avoiding the "risks" of epidurals while simultaneously exposing their own babies to an increased risk of death.
When their self-favoring views about their behaviors and their future are challenged, people engage in a variety of strategies to preserve these views ... People are quite capable of finding fault with threatening health messages, suggesting that they endeavor to maintain positive views of their health.
Homebirth advocates react very angrily when it is pointed out to them that they are willingly exposing their babies to an increased risk of death. The most common reaction is flat out denial. However, homebirth advocates also strike back at the warnings of obstetricians by claiming that obstetricians are only trying to increase business for themselves, when this is obviously false.
Klein and Cerully point out that self enhancing health beliefs are often accompanied by illusory positive beliefs:
... [R]esearch in the health domain has been instrumental in testing a key theory introduced by Taylor and Brown, which argued that positive illusions (e.g., unrealistic optimism, illusion of control, and overestimations of ability) were adaptive. Although there is a fair amount of evidence that positive beliefs such as optimism are related to favorable health outcomes, there is also growing evidence that illusory positive beliefs are associated with negative health outcomes such as ineffective health decision-making and poor processing of health information... The distinction between positive beliefs and positively biased beliefs is a crucial one that has been blurred in many tests of positive illusions theory, and has been highlighted by research in a health context.
All three types of positive illusions are fundamental to homebirth advocacy. Homebirth advocates are unrealitistically optimitistic about their incidence of childbirth complications. They believe that health behaviors like good nutrition can prevent childbirth complications, and they grossly overestimate their ability to manage complications when they happen.
The bottom line is that even homebirth advocates who demonstrate intellectual awareness of the increased risk of preventable neonatal death at homebirth, act in ways that indicate they do not really appreciate the risks. One of the most important motives for treating the risks of homebirth so cavalierly is the desire for self-enhancement. It is difficult to feel superior about the choice of homebirth when the risks are taken into account. Since feeling superior is so important, the only logical alternative is to discount the risks.
Labels: risk
What does it mean to understand a risk?
Much of the disconnect between homebirth advocacy and obstetrics hinges on the fact that homebirth advocates do not understand the risks involved. Since a woman can only make an informed decision if she understands the risks, it is important to assess understanding. On the face of it, this may seem to be a simple task; either she understands or she doesn't. In reality, the assessment of the understanding of risk is more complex.
Before we discuss the criteria for determining whether a woman understands a particular risk, let us look at the way knowledge of risks is handled in the homebirth advocacy community. The fundamental method for dealing with risk among homebirth advocates is to simply pretend that it doesn't exist. So, for example, the entire homebirth advocacy community engages in a community wide fantasy that homebirth is as safe as hospital birth.
The pretending extends to the realm of specific complications. Homebirth advocates understand that complications can occur, but they like to pretend that risk is an all or nothing phenomenon. In other words, according to the "reasoning" of homebirth advocates, if breech birth were risky, all breech babies would die. Therefore, by this "reasoning", the fact that most breech babies survive vaginal delivery shows that doctors vastly overstated the risks. Of course, no obstetrician would ever claim that the risk of death at breech vaginal delivery involved any more than a small fraction of babies. By deliberately distorting what obstetricians say, and by insisting that risk means death for 100% or at least some large proportion, homebirth advocates can continue to live the fantasy that birth should be "trusted".
These are merely the errors of reasoning made routinely by homebirth advocates. We have not even addressed the fact that homebirth advocates lack fundamental knowledge about the nature and magnitude of most risks. As a general matter, homebirth advocates "understanding" of risk is based on magical thinking and ignorance. In other words, they don't understand risk at all.
How can we tell when someone does understand a risk, and is therefore capable of making an informed decisions about accepting or refusing treatment? Neil Weinstein discusses the criteria in his paper
What Does It Mean to Understand a Risk? Evaluating Risk Comprehension, published in Journal of the National Cancer Institute Monographs No. 25. Weinstein suggests that the knowledge needed for understanding of risk can be group into three categories: "the identity and severity of the potential harm, the likelihood of harm under various circumstances, and the possibility and difficulty of reducing that harm.
As Weinstein states:
Judging the severity of a hazard requires more than a vague understanding that an activity is "bad for you" or that it "causes cancer." Unless a person has a reasonably complete knowledge of the undesirable consequences of that activity — both what outcomes can occur and how serious these outcomes are — he or she is not in a position to decide how negative the consequences might be.
In the case of childbirth risks, homebirth advocates fail to meet this most basic criterion. Indeed, rather than having a reasonably complete knowledge of undesirable consequences of a particular choice (such as breech vaginal delivery), homebirth advocates pretend that there is no increased risk, have literally no idea of the magnitude of the risk (because they are pretending it is zero), don't understand the factors that increase or decrease the risk, and don't understand the negative consequences.
Homebirth advocates are not alone in their failure to acknowledge real risks.
Quite a few studies have asked smokers how their risk of becoming ill from smoking compares with the risk of the average person ... Ayanian and Cleary found that 71% of smokers believed their personal risk of heart attacks to be average or below average when compared with the risk of other people of their age and sex, and 60% believed that their personal risk of cancer was average or below... In no case did smokers acknowledge that their risk of lung cancer, heart disease, or emphysema was "moderately," "substantially," or "much" higher than that of the
average person...
In other words, those at increased risk are the people who are least likely to understand and acknowledge the risk.
Moreover:
... Chapman et al. found that smokers maintain a constellation of comforting, risk-minimizing beliefs. About one third of smokers, for example, agreed that "Many people who smoke all their lives live to a ripe old age, so smoking is not all that bad for you..."
Homebirth advocates practically specialize in "comforting, risk-minimizing beliefs." These range beliefs that nutrition can prevent complications to beliefs that pretending you won't have complications (birth "affirmations") can prevent complications.
Homebirth advocates are very much like smokers when it comes to risk minimizing rationalizations.
Research has shown that risk perception is not an unbiased appraisal of information, but rather an attempt to seek the most comforting view of one’s personal vulnerability that fits within the bounds of the evidence. As a result, whatever people believe about the risks faced by others, they tend to believe that their own personal risks are less...
This optimistic bias appears to be equally descriptive of adults and adolescents. The magnitude of unrealistic optimism (i.e., the difference between risk estimates for oneself and for others) varies from hazard to hazard, but it is particularly large for problems, like lung cancer, that are believed to be preventable by individual action.
It is this point that underlies obstetricians negative reaction to women who claim that they "understand" the risks of refusing interventions. Obstetricians, like all doctors, know from research papers and from vast personal experience that lay people routinely misunderstand risk because they assume that bad things won't happen to them. Obstetricians do not believe women who claim that they understand the risks of VBAC or the risks of vaginal breech, because most lay people do not understand the risks of adverse outcomes, and those at greatest risk of an adverse outcome are least likely to understand it.
Labels: risk
Risk perception: control, choice and cause
One of the interesting things about risk perception is that it is often unrelated to the actual level of risk. You can see this at work in homebirth advocacy, where the risks of homebirth itself are far greater than advocates understand, and the "risks" that advocates are trying to protect themselves from are far smaller than they appreciate.
David Ropeik, Director of Risk Communication at the Harvard Center for Risk Analysis, discusses the causes of misperception of risk in his article
The Consequences of Fear. In particular, he mentions three factors, control, choice and origin, that are especially relevant for understanding the misperception of risk among homebirth advocates.
Take the issue of choice, for example. It is widely accepted among scholars of risk analysis that risks over which we feel as though we exercise control are perceived to be smaller than risks that are imposed from outside.
We sometimes fail to take adequate precautions against relatively larger risks that do not cause elevated concern. Roughly 20% of Americans still do not wear safety belts in motor vehicles. The risk perception literature would suggest that this is, in part, because we have a sense of control when we are behind the wheel, and the risk of crashing is both familiar and chronic—factors that make risks seem less threatening. Consider the public health ramifications here. The US National Highway Traffic Safety Administration estimates that if safety belt usage increased to 85%, 2,700 lives would have been saved in 2002...
In other words, people not only tolerate the substantial risk of not wearing a seatbelt, but they perceive the risk to be relatively small, when, in fact, it is relatively large compared to risks that evoke more fear, like the risk of a plane crash or a terrorist attack.
A second factor that modifies perception of risk is a sense of control. Risks that are deliberately chosen seem smaller than risks that are imposed by external forces.
many Americans sought a sense of control and safety after 9/11 by driving instead of flying. Air arrivals in Las Vegas were down 6.5% and motor vehicle arrivals were up 7.3% at the end of April 2002, compared with the same period in 2001, according to the Las Vegas Convention and Visitors Authority. Consider the public health ramifications of such a choice. Driving is far more likely to result in injury or death. A study by Michael Sivak and Michael Flannagan of the Human Factors Division at the University of Michigan Transportation Research Institute found that roughly 1,000 more Americans died in road accidents during October–December 2001 than would have been expected based on a comparison between figures from January–August 2000 and January–August 2001.
Similarly, there is a sense of control that comes from giving birth at home, which is safe and familiar, as opposed to giving birth in the hospital, which is a strange and psychologically uncomfortable place. Ahtough the risks of homebirth are far higher than the "risks" (real or imagined) of hospital birth, that is not how they are perceived by homebirth advocates. Homebirth advocates claim that an advantage of homebirth is the fact that a baby cannot acquire MRSA or other "superbugs" at home, although MRSA is almost unheard of in a newborn nursery. In reality, homebirth has a risk of neonatal death that is orders of magnitude higher than any risk posed by MRSA in the newborn nursery.
The third factor is that risks of technology are widely perceived to be greater than risks from nature, even though in many cases they are not.
...many people fail to protect themselves adequately from the sun, in part because the sun is natural and because, for some of us, the benefit of a healthy glowing tan outweighs the risks of solar exposure. However, solar radiation is widely believed to be the leading cause of melanoma, which will kill an estimated 7,910 Americans this year.
It is axiomatic among homebirth advocates that childbirth is inherently safe because it is natural. This is not and has never been true.
Homebirth advocates are absolutely certain that the risks of homebirth are so small as to be trivial and are far outweighed by the risks of hospital birth. This is a misperception of the risk. Because homebirth encourages a sense of control, because homebirth is freely chosen, and because birth is natural, homebirth advocates misperceive the real risks.
Labels: risk
How much risk is too much risk?
Homebirth advocates and natural childbirth advocates, (and advocates of "alternative" health in general) tend to be obsessed about environmental exposures. They express concern about not eating "right" in pregnancy. They are sure that exposure to any and all medication is toxic. They chide other women about the "risks" of epidural. Before we look at the real risks of various environmental exposures, we need to ask a threshhold question:
How much risk is too much risk?
In other words, at what point (1 in a hundred, 1 in a thousand, 1 in a million) is the risk of death or injury to a baby or a mother too great to be acceptable? That point may be different for each individual, but logically speaking, we should be able to conclude that risks that are higher than the chosen risk level are too high, and risks lower than the chosen risk level are not high enough to warrant concern. It would not be logical to claim that some risks are too high, but other, even higher risks, are not too high.
So where do you draw the line? How much risk is too much risk for you?
Labels: risk
Public understanding of statistics
One of the biggest problems in homebirth advocacy is that most homebirth advocates do not understand statistics. This problem is not restricted to homebirth advocates and represents a serious problem for society in the US. Americans are exposed to a tremendous amount of statistical information and are required to make many decisions based on statistical information, but lack any foundation in understanding and utilizing statistics.
A recent article in the journal Public Understanding of Science asks the question
Do we need a public understanding of statistics? We live in a statistics-rich society: statistics permeates many aspects of life—from media, health, and work to citizenship. In the media, we can observe a growing emphasis on statistical results. This is particularly the case in health and medical reporting which tend to be the most compelling scientific issues for citizens ... The understanding of these statistical components is crucial to help citizens participate in public debate and arrive at political decisions.
Statistical misunderstandings are very common and lead to cynicism about science and medicine.
Statistics requires the ability to consider things from a probabilistic perspective, and to employ quantitative technical and abstract concepts such as significance, margin of errors, and representativeness. Since these concepts are difficult to understand, statistical misunderstandings can often be observed in the everyday but also in the media and research results. It is important to clear up these misunderstandings, as they lead to the misuse of study results, and the development of a distrustful or cynical attitude toward statistics.
Homebirth advocates often have trouble understanding the risks of homebirth because they have minimal civic scientific literacy, defined as:
Miller has defined civic scientific literacy as a three-dimensional construct. Precisely, a scientifically literate citizen needs to have: "(1) a vocabulary of basic scientific constructs sufficient to read competing views in a newspaper or magazine; (2) an understanding of the process or nature of scientific inquiry; and (3) some level of understanding of the impact of science and technology on individuals and on society"
In the context of homebirth advocacy, I find the second to be especially important:
The second dimension of civic scientific literacy requires that an individual display a minimal understanding of the empirical basis of scientific inquiry.
That is why I often suggest that homebirth advocates ready, study and learn about the scientific method and basic statistical analysis.
Labels: risk
Affective feeling and the perception of risk
It is clear that people base their assessments of risk on more that the actual data about specific risks.
Trust, Emotion, Sex, Politics, and Science: Surveying the Risk-Assessment Battlefield by Paul Slovic explores these factors that modulate our perception of risk.
On page 6 of the article, Slovic discusses the ways in which our emotions change our perception of risk. He discusses the impact of affect, a term he uses to describe whether a person has a positive or negative view of the subject under discussion. According to Slovic:
Support for the conception of affect as an orienting mechanism comes from a study by Alhakami and Slovic. They observed that, whereas the risks and benefits to society from various activities and technologies ... tend to be positively associated in the world, they are inversely correlated in people’s minds [My comment: In other words, although activities that have high benefits have high risks, people tend to think that activities that they feel are highly beneficial have low risks and vice versa.]. Alhakami and Slovic found that this inverse relationship was linked to people’s reliance on general affective evaluations when making risk/ benefit judgments. When the affective evaluation was favorable (as with automobiles, for example), the activity or technology being judged was seen as having high benefit and low risk; when the evaluation was unfavorable (e.g., as with pesticides), risks tended to be seen as high and benefits as low. It thus appears that the affective response is primary, and the risk and benefit judgments are derived (at least partly) from it.
If Slovic is correct, it would go a long way toward explaining the disparity between homebirth advocates' perception of risk and the very different actual risks. So, for example, homebirth advocates strongly value homebirth. They think that it has high benefits, and therefore they assume that it has low risks. On the other hand, homebirth advocates are contemptuous of the use of pain relief in labor, and therefore grossly overestimate the risks of epidurals.
The reality is that homebirth has an excess neonatal mortality rate in the range of 1-2/1000 and epidural has an excess neonatal mortality rate of 0. Homebirth has an unknown risk of maternal mortality (not enough homebirths have been evaluated to reach a conclusion) and epidurals have an excess maternal mortality rate in the range of 7/1,000,000. So from a purely factual point of view, homebirth carries greater risk of death than epidurals.
Homebirth advocacy websites and publications are replete with condemnation for the "risks" of epidurals (including entirely fabricated risks like impairment of the mother-infant bond), yet they gloss over, fail to mention or are entirely dishonest about the risks of homebirth.
Labels: risk
C-section rates and the calculation of risk
The March 1 issue of the New England Journal of Medicine has a commentary on the current C-section rate. In
Cesarean Delivery and the Risk–Benefit Calculus, Ecker and Frigolleto begin by describing the current situation:
In 1937, an article in the Journal describing 10 years of births at Boston City Hospital revealed an overall rate of cesarean delivery of about 3%. Recently released 2005 data on cesarean deliveries show that contemporary rates are 10 times as high,.. Indeed, of the 20th century's many changes in obstetrical care ... few have generated more attention and debate ... than this seemingly inexorable rise.
The rising rate of cesarean section has been closely associated with the increasing safety of the procedure.
In 1937, 6% of primiparous patients died after cesarean delivery, a risk that has decreased by a factor of nearly 1000 ... Certainly, in earlier eras, the specter of death during childbirth hovered over each decision to proceed to cesarean delivery, and everyone involved tolerated a greater degree of risk of maternal or neonatal complications from vaginal delivery than we accept today. As the risk associated with cesarean delivery decreased, practitioners and patients felt more comfortable choosing this option, even in situations in which there was less potential benefit ...
Critics claim that the rising C-section rate is the result of doctors attempting to maximize profit and convenience, but the authors note that the C-section rate is rising around the world, and in countries where the economic incentives are very different. They believe that the increase is due, in large part, to the profound changes in both patient and provider calculations of risk and in the changing expectations of how much risk is appropriate.
Vaginal breech deliveries are no longer recommended, since the 3% associated neonatal morbidity has been judged excessive, and such deliveries have been abandoned. Careful and repeated study of a trial of labor after prior cesarean delivery has led some to conclude that elective repeated cesarean delivery, because it is associated with lower rates of major complications (including uterine rupture) and lower rates of poor perinatal outcome (including hypoxic–ischemic encephalopathy), is "safest," ... Furthermore, better data describing the complications associated with the use of forceps or vacuum extraction ... have led to a decrease in the number of operative vaginal deliveries (from 9.5% in 1994 to 5.6% in 2003) that parallels the increase in cesarean deliveries ...
Critics of the current C-section rate claim that many cesarean sections are unnecessary, in retrospect. Obstetricians know this, but they also know that many C-sections must be done to prevent rare, but serious complications:
For example, among women without gestational diabetes whose fetuses have an ultrasound-predicted weight of more than 4500 g (10 lb), it has been estimated that 3695 cesarean deliveries are needed to prevent one permanent brachial plexus injury — a number that reflects both the imprecision of in utero estimations of fetal weight and the reality that most large infants will undergo vaginal delivery without injury. To cite another example, "only" 3% of infants with breech presentation who are delivered vaginally will have traumatic injury. And most babies delivered by cesarean section because of a "nonreassuring" fetal heart-rate tracing are born healthy and vigorous, reinforcing the perception that cesarean deliveries are not needed in such circumstances.
As Ecker and Frigoletto point out, the most important variable is the level of risk that is considered acceptable:
But the key question centers on both the number needed to treat to avoid one adverse neonatal outcome and the level of risk that is currently considered acceptable... [T]he risk that women are now willing to assume in exchange for a measure of potential benefit, especially for the neonate, has changed: for many, the level of risk of an adverse outcome that was tolerated in the past to avoid cesarean delivery is no longer acceptable, and the threshold number needed to treat has thus been reset.
Labels: risk
Lay epidemiology and risk assessment
I have often noted that homebirth advocates and DEMs lack background in and understanding of the scientific method and statistics. That does not mean that lay people do not try to make sense of medical events that occur to them. These attempts to understand why diseases or medical complications happen to specific people in specific instances has been termed "lay epidemiology". This is to distinguish it from the discipline of epidemiology that looks at the occurence of health and illness in large populations.
In
Thinking about risk. Can doctors and patients talk the same language? Misselbrook and Armstrong note that doctors and patients have very different ways of thinking about risk:
First we must recognize that patients have their own risk models. These bear little relation to the mathematical risk models used by doctors. Davison and his colleagues found that the lay classification of risk was based on a polarity model rather than the gradation of a continuing spectrum. People saw themselves as either high risk or low risk. This model identified ‘likely candidates’ for illness. Thus a beer-swilling heavy smoking overweight man would (rightly) be seen as at high risk of a heart attack. However, if he did not have a heart attack and his healthy living neighbour did, Davison found that a second element in the lay risk model came into play. Luck, fate and destiny were also perceived to determine health outcomes.
Remember, John Everyman wants to know whether he himself is going to have a heart attack, and my mathematical model will not tell him. If we are not talking about populations but about individuals, then a high risk/low risk model feels like a better fit. It provides the patient with a map to enable them to function and to cope in an uncertain and threatening world.
In other words, doctors think about risks in term of numbers. An excess risk of neonatal mortality at homebirth of 1-2/1000 means that 1-2 babies will die unnecessarily at homebirth and that the tragedy of neonatal death could befall any patient. Patients, on the other hand, have a very different understand of what this means. They do not realize that the risk is spread throughout the population and tend to think that bad outcomes happen only to high risk people. Judging themselves to be low risk, they think that it is exceedingly unlikely that a bad outcome can happen to them, and that if it does happen, it is because of fate ("some babies are meant to die").
Simply put, doctors know that the risk of excess neonatal death means that anyone can lose a baby at a homebirth. Patients on the other hand, while aware of the risk, think that it doesn't really apply to them. Couple that with the fact that doctors have seen so many patients that they have direct personal experience with neonatal death, while most patients don't know anyone who lost an otherwise healthy baby, and you can begin to see how doctors and patients talk right past each other when discussing the risk of homebirth.
Doctors see the risk of homebirth as small, but real. Patients, on the other hand (particularly homebirth advocates), tend to believe that they are not at risk for the bad outcomes, so in their minds, the small risk is essentially no risk.
Labels: risk
Reasoning from personal experience: how lack of experience leads homebirth advocates astray
Reasoning from personal experience is a vitally important skill. For hundreds of thousands of years of human history, it was essentially the only way to reason since there was no written documentation of anything and no scientific study. Reasoning from personal experience can lead us astray, and that is especially obvious in today's world where assertions about past events can be checked against documented historical data, and where massive numbers of events can be aggregated by statistical methods to produce far more accurate assessments.
Erroneous reasoning from personal experiece can be something as trivial as having a pair of "lucky" socks. Something special happened once when you wore the socks and now you deliberately wear them when you are in need of good luck. Rationally, you know that wearing the socks cannot make things happen, but the mental connections created by personal experience are difficult to shake.
Reasoning from personal experience is biased by things that people never think about. For example, it is common for homebirth advocates to say that "if birth weren't safe we wouldn't be here". Not only is that statement wrong from a statistical point of view (since many women and children can die in childbirth and the human species can still survive), but it also suffers from a serious flaw in logic. Yes, "we" are still here. However there are untold millions, perhaps billions of people that would be here if an ancestor had not died in childbirth. Every time a woman or baby dies in childbirth, their putative descendants --- children, grandchildren, and all other future generations --- are obliterated along with them. So the fact that "we" are here tells us nothing about death in childbirth since anyone who died has no descendants to report personal experience of death in childbirth.
Reasoning from personal experience is a particular problem in the homebirth movement. The inherent problems from reasoning from personal experience are magnified by the fact that homebirth advocates, and even homebirth practitioners have very limited experience of birth. Fortunately, modern obstetrics has succeeded in lowering maternal and neonatal mortality rates to very low levels. Therefore, in order to have personal experience of a maternal or neonatal death (as participant or practitioner), you'd need to seem hundreds, perhaps thousands of births. In this country today, most women have 2-3 children. It is unlikely that either they or their children will die. They have the personal experience of safe homebirth, but that actually tells us nothing about the safety of homebirth. Similarly, homebirth midwives rarely deliver more than a few patients a month. At that rate, it could take decades to be confronted with a poor outcome. A midwife may pride herself the healthy outcomes of the homebirths that she attended; but in reality, the fact that all of the outcomes were good is just because she hasn't attended many deliveries.
That's why the perceptions of obstetricians about the risks of childbirth are likely to be much more accurate than those of lay people or homebirth midwives. After you've seen a thousand deliveries, you have a much more accurate idea of what can happen in childbirth.
So when it comes to homebirth, reasoning from personal experience on the part of lay people or homebirth midwives is more likely to lead to faulty conclusions than not. For this reason (and others) statistics are the only reliable method for accurately assessing risk.
Labels: midwifery, risk
The inherent risks of childbirth: perinatal mortality
We have already seen how natural childbirth advocates grossly underestimate the inherent risks of childbirth to the mother. The inherent risks to the baby are much higher.
Death of babies is measured in several different ways, and it is very important to understand what statistic is being used. Death can be described as intrapartum (during labor), perinatal ("around" the time of birth, which may include stillbirths, deaths during labor, deaths immediately following labor, and deaths up to 7 days after birth), neonatal (during labor and up to 28 days after birth). This is in contrast to infant mortality, which usually measures deaths up to 1 year after birth.
Modern obstetrics has had the biggest impact on deaths of babies in labor, to the point where death in labor is virtually non-existent in first world countries. Indeed, largest share of the risk that homebirth poses to babies appears to be due to deaths in labor. When a complication occurs during labor, immediate delivery (usually C-section) is required. That simply cannot happen at home, and some babies will die as a result.
To understand tremendous risk that labor poses to babies, it is instructive to look at statistics from third world countries where there is limited access to modern obstetrics.
Perinatal mortality attributable to complications of childbirth in Matlab, Bangladesh is a study that was specifically designed to look at the death rate of babies due to labor complications, the number of such deaths and the causes. The study found that the overall perinatal mortality rate was 71.4/1000. In other words, 7% of all babies died during labor or in the immediate period thereafter.
The statistics are even more dramatic when you look at the death rates in specific situations. The perinatal death rate for obstructed labor was over 60%! Compare that to a death rate of essential zero for obstructed labor in the US. The death rate from breech presentation was over 20%. In other words twenty percent of all babies who started labor in the breech presentation died, as compared to essentially zero deaths due to breech delivery by C-section in the US. Of the women who developed eclampsia (seizures) during labor, 40% lost their babies. Compare that to the US where eclampsia is almost unheard of.
Around the world, the day of birth is the single most dangerous day of childhood. More deaths occur on the day of birth than on any day in the subsequent 18 years. Birth is not safe because it is natural. Birth in nature is among the most perilous stages of human life. Modern obstetrics has changed all that, but birth has never been, and probably will never be inherently safe. Anyone who tells you otherwise does not know even the most basic facts about childbirth.
Labels: neonatal mortality, risk
The inherent risks of childbirth
So we've seen that homebirth and natural childbirth advocates (like many Americans) have trouble evaluating risk. They have difficulty understanding relative risk (how one risk compares to another risk) and they have difficulty evaluating sources for the accuracy of their claims. There is an additional component to risk assessment for homebirth and natural childbirth advocates. They are often factually misinformed about the actual risks. Nowhere is that more apparent than in their almost complete lack of knowledge about the inherent risks of pregnancy and childbirth.
The first clue to this serious misunderstanding is the claim that childbirth must be safe because it is "natural". Natural does not mean safe, and we are pretty clear about that in other areas of life. For example, natural disasters, such as hurricanes and earthquakes are 100% natural. Nonetheless, we know that they are responsible for a tremendous amount of death, suffering and destruction. Natural means one thing only: it happens in nature. It tells us absolutely nothing about whether it causes death or other serious effects.
The second clue to this serious misunderstanding is the claim that childbirth must be safe because "we are still here". This is evidence of basic lack of knowledge about biology. The fact that "we are still here" only tells us that in every generation, the number of people who lived exceeded the number who died. It doesn't tell us anything about the ratio. So, for example the population will grow at a certain rate if each couple has 3 surviving children. It does not matter whether the couple had 3 children, all of whom survived, or 10 children, 7 of whom died.
We know from the biology of other animals that reproduction has a tremendous amount of wastage. We've all seen nature shows about sea turtles who lay hundreds of eggs, with the result that only a few baby turtles survive the treacherous walk across the beach to the safety of the ocean. We know that some animals, like salmon, give up their own lives in the process of reproduction. The fact is, there is a tremendous amount of wastage in human reproduction also. The miscarriage rate for established pregnancies is 20%. That means that 1 in 5 pregnancies will not survive to result in a live birth. Pregnancy and childbirth also have a "wastage" rate. In nature, many women and babies did not survive the process. That is a natural part of human reproduction.
Let's take a look at historical evidence about death in pregnancy and childbirth. Irvine Loudon is one of the premier historians working to understand the history of human pregnancy and birth. In the article
Maternal mortality in the past and its relevance to developing countries today, there is extensive exploration of the historical data on maternal mortality in the United Kingdom. Looking at the maternal mortality data for 1872-1876, we find a maternal mortality rate of approximately 400/100,000 with the following causes:
| cause of death | % |
| Puerperal fever | 55.5 |
| Hemorrhage | 22.5 |
| Eclampsia | 11.6 |
| Miscarriage and abortion | 4.0 |
| Postpartum psychosis | 2.5 |
| Embolism | 2.0 |
| Ectopic | 0.2 |
| Other | 0.8 |
By contrast, the maternal mortality rate today is in the range of 8/100,000.
What were maternal mortality rates prior to the late 19th century? According to the works of other historians which Louden quotes:
They found maternal mortality rates were certainly higher at 400-500 per 100000 births throughout the 19th century. It was a bit higher at the beginning of the 19th century and was up to perhaps 1000 per 100000 births in the early part of the 18th century. I have a graph in my book [Loudon I. Death in childbirth. Oxford: Clarendon Press, 1992] that shows maternal mortality stretching back in history and, as you go back, it goes up very slightly and then we lose track because there really are no data as yet.
This data is fairly consistent with the maternal mortality rates that we see today in parts of the world that don't have access to modern obstetrics.
What conclusion can we draw from this data?
Giving birth is and has always been inherently dangerous. From the early 18th century on back, 1% or more of births resulted in the death of the mother. What's really amazing to consider is that the chance of the baby dying was always dramatically higher.
Addendum: To put a 1% maternal mortality rate in perspective, it is twice as high as the mortality rate for receiving a kidney transplant, and a bit less than half the mortality rate of having "triple bypass" heart surgery.Labels: risk
Risk Assessment 2
In order to assess risk, you need to understand the reliability of information provided by various sources. We all know, for example. that just because it is written in the newspaper, that does not make it so. This is especially important when considering medical information, because newspapers often sensationalize the results of medical trial or may completely misunderstand the scientific information they are trying to present.
One of the best explanations of evaluating risk that I have seen is
Risk in Perspective: A Consumer Guide to Taking Charge of Health Information prepared by the Harvard Center for Risk Analysis. This is a six page brochure designed to help people make sense of conflicting sources of health information. It is a very valuable explanation of risk, and worth reading in full, especially because the cartoons are very funny. The text is serious, though. One section struck me as relevant for our discussions:
Health information can be based on untested claims, anecdotes, case reports, surveys, and scientific studies. Scientific studies, which take samples and apply the results to the whole population, often provide the best clues about health. Nonetheless, many studies are needed to be confident about an answer. The following are some factors that might help you judge information:
| Less reliable (less certain) | More reliable (more certain) |
| One or a few observations | Many observations |
| Anecdote or case report | Scientific study |
| Unpublished | Published and peer reviewed |
| Not repeated | Reproduced results |
| Nonhuman subjects | Human subjects |
| Results not related to hypothesis | Results about tested hypothesis |
| No limitations mentioned | Limitations discussed |
| Not compared to previous results | Relationship to previous studies discussed |
If you read these guidelines, it is not difficult to understand that most of the homebirth literature and natural childbirth literature fall into the category of less reliable, and is almost always superceded by scientific evidence that is more reliable. So, for example, anecdotes are not reliable since they tell us nothing about what happens to most people. Information that is not published in peer review scientific journals is not reliable compared to information that has been published in a peer reviewed journal. Bits of information scavenged from a variety of studies that were unrelated to the claim being discussed are far less reliable than actual studies of the specific claim.
It is important to keep all of this in mind as we move on to discussing the actual risks of various interventions and the actual risks of homebirth.
Labels: risk
Risk assessment
Risk assessment is integral to understanding the issue of homebirth. Obstetricians are generally appalled by the idea of homebirth since they believe it is carries significant risks for the baby, and, to a lesser extent, for the mother as well. Homebirth advocates, on the other hand, are always talking about the puported risks of obstetrical interventions and appear to know little if anything about the risks of childbirth. So in order to get at the truth of the matter, we should take a look at risk, how it is assessed and how it is perceived.
Before we start, I want to make a specific claim. As we look at the various aspects of risk assessment, you will see how they support my claim. This is the claim:
Homebirth advocates are, in general, ignorant of the risks of childbirth. Furthermore, they grossly overestimate the "risks" of obstetric technology. These problems are compounded by an inability to understand and evaluate relative risk.To a certain extent, homebirth advocates are like other Americans in that they do not understand the concept of relative risk and therefore make judgments that are not based on factual evidence. However, I believe that there is an additional cultural factor at work in homebirth advocacy. That is the cultural phenomenon called reflexive doubt. This phenomenon has been identified and discussed in detail by Prof. Craig Thompson. He elaborates on this in an article entitled
What Happens to Health Risk Perceptions When Consumers Really Do Question Authority?:
I offer an alternative way of conceptualizing consumer health risk perceptions by using the natural childbirth community as a context that helps us understand how groups of people come to deeply believe in anti-establishment risk norms. This community of reflexive doubt questions whether a hospital is the safest place to labor. Natural childbirth activists believe that low-tech midwifery (preferably in a home setting) provides the best labor outcomes, except for in a small percentage of high risk cases. They also believe that the medical practices of childbirth pose a host of unnecessary and avoidable risks. This community spins an elaborate historical account of how the medicalized birth model gained wide-spread acceptance through a joining of social and political forces and how the model has been established through obstetrical training, hospital practices, and medical technologies.
The natural childbirth community encourages health-care choices, such as midwife attended home births, that are substantially different than the risk norms endorsed by the mainstream medical community. Couples who accept the natural childbirth community's risk perceptions are neither reckless nor relying upon inaccurate decision rules. Rather, they have developed an alternative belief system that comes from an anti-establishment perspective on the risks they attribute to the medicalized birth model. Importantly, their beliefs are far more than an abstract system of thoughts. The natural childbirth model shapes childbirth choices by being accepted as a structure of feeling. These feelings and personal preferences are reinforced through couples' experiences of the medical system and their contrasting encounters with midwives, natural childbirth instructors, and other couples who embrace this alternative construction of risk.
...The risks singled out by the natural birth model express cultural anxieties over the unintended and dehumanizing consequences of technology; the loss of individual independence through the workings of complex 'expert' systems; and a political project of supporting midwifery over the socially-accepted knowledge of the medical establishment. (emphasis added by me)
The concept of reflexive doubt is similar to the idea of defiance that I have spoken about before. If a medical expert says it, the response of the homebirth community is to deny it whether they have any evidence or not. So if a practice is considered safe, homebirth advocates insist that it is dangerous. If a practice is considered dangerous, homebirth advocates reflexively insist that it is safe. Hence the otherwise incomprehensible claims that epidurals pose unacceptable risks while maternal aspiration is a risk that is so small that it should be ignored. Why is this incomprehensible? Because the risk of death from a labor epidural is actually LESS than from maternal aspiration. I would suggest that homebirth advocates literally have no idea that the chances of dying from aspiration are significantly greater than from a labor epidural.
This is the background to a discussion about relative risk. In a future post, I will discuss the actual assessment of risk and how it has been distorted by the cultural imperatives of the homebirth movement.
Labels: risk
What are the risks of interventions?
Many homebirth advocates are absolutely certain that interventions such as C-section, epidural and pitocin have significant risks, risks that outweigh the chance of the baby dying at a homebirth. They are correct in that any procedure has risks as well as benefits. They are wrong in what they imagine are the magnitude of the risks. Since everyone is constantly chiding me for failing to consider the risks, let's hear what they are. Let the rest of us know what
specific risks exist and what the magnitude of the specific risk is. If you don't know how likely that risk is to occur, than you really don't know if it is a relevant consideration when considering the known risks of homebirth. I'll start us off with what is probably the most commonly occuring risk, the risk of spinal headache after epidural, which is approximately 1%. If you consider that more than a million women receive labor epidurals each year, that means that 10,000 women have spinal headaches.
Labels: risk
Homebirth and gambling
Homebirth is like gambling. You are always playing the odds.
In a typical lottery game like Powerball, the odds of winning the Jackpot are very low, less than 1 in 146 million. Despite the low odds, millions play every week, and every few weeks, someone wins the jackpot.
In contrast, playing the odds in homebirth is a much better bet. The chance of a preventable neonatal death at homebirth appears to be approximately 1-2/1000, so the odds are high that everything will be fine. Nonetheless, you are still gambling since for every 1000 homebirths, 1 or 2 babies will die needless, preventable deaths. Indeed, the odds of your baby dying at a homebirth are about 10,000 times higher than your odds of winning the lottery.
So every homebirth is a gamble. The odds are good, but you are still gambling with a baby's life.
Labels: philosophy, risk
Reconciling normality and risk
How do homebirth advocates reconcile the concept of risk with the normality of birth? If birth "normally" proceeds uneventfully, why do midwives use so many different tests to determine who is at risk? Why are so many patients transferred to hospital care before the start of labor? Why are a substantial portion of patients transferred to hospital care during labor?
For example, in the Janssen and Davis study 7258 women intended to give birth at home, but 1840 (25%) were transferred to hospital care even before labor began. Then an additional 655 were transferred during labor or immediately after delivery. So fully 34% of midwife patients intending homebirth could not or did not have an uncomplicated homebirth.
If 1/3 of "normal" patients develop complications, what does "normal" mean?
Labels: risk
How do we determine an acceptable level of risk?
Everyone acknowledges that some situations are high risk and some are low risk. Risk, of course, exists on a continuum.
At what point do direct entry midwives and homebirth advocates consider that the risk in a situation justifies moving a woman from low risk to high risk? Is it a specific number (the chance of a problem in this situation is x%) or is it based on rules about particular situations? Why is it that some DEMs place certain women in the low risk group (postdates, for example), while obstetricians would consider them high risk?
Labels: risk
