Saturday, April 05, 2008

C-sections and diminishing returns

There's seems to be a great deal of confusion about my comments that a 32% C-section rate is too high. I am NOT saying that the C-section rate should be arbitrarily set at a certain point, and any neonatal deaths above that point are irrelevant. I am saying that, whether we realize it or not, the controversy over the C-section rate reflect both statistics and values, so it is critically important to explore what they are.

All treatment decisions are governed by the law of diminishing returns. This is a principle first described in economics that applies to many other areas as well. It must be taken into account when determining what C-section rate is appropriate. The following is a hypothetical example of how the law of diminishing returns works, which will help us identify the issues raised by the rising C-section rate.

Imagine a hypothetical first world country that has 1 million births per year. In this hypothetical country, we are able to analyze the number of lives saved by C-sections and we are able to analyze it in hindsight so that we know which C-sections were necessary. As the C-section rate rises, the numbers of lives saved drops off (diminishing returns). In our hypothetical country, we can chart how many lives are saved for each percentage point of the C-section rate. Each percentage point of the C-section rate represents 10,000 C-sections. Our chart might look something like this:

C-section ratelives saved/10,000 C-sections
0-5%%20,000 (every mother and baby)
6-10%10,000 (every baby)

We can see the law of diminishing returns in action here. At a C-section rate from 0-5%, every C-section is necessary, and every C-section saves the life of both mother and baby. From 6-10% every C-section is necessary and saves the life of the baby. From 11-15% half the C-sections are necessary, resulting in a savings of 5000 lives. At rates higher than 15%, retrospective analysis reveals that far fewer C-sections are life saving. By the time a C-section rate of 35-40% is reached, only one additional baby will be saved every other year.

The results can be expressed another way. We can determine retrospectively how many C-sections were unnecessary. Here's that chart:

C-section rateunnecessary C-sections/10,000

That's not all we have to take into account. Though the risk of maternal death from a C-section is low, it is not zero. As greater numbers of C-sections are performed, maternal deaths will become an every greater issue. Let's assume that the maternal death rate solely attributable to C-section is 1/10,000. At low C-section rates, where almost all C-sections are lifesaving, a maternal death rate of 1/10,000 seems very small. As the C-section rate begins to rise, look what happens. For C-section rates from 11-15%, 5000 babies will be saved per 10,000 C-sections, and 1 mother will die. From 21-25%, 50 babies will be saved per 10,000 C-sections, 9,950 unnecessary C-sections will have been performed and 1 mother will die. By the time you reach 31-35%, only 1 baby will be saved every other year per 10,000 C-sections. 9,999/10,000 C-sections are unnecessary and 1 mother will die. A C-section rate of 36-40% would save only 1 baby every 10 years, almost every C-section is unnecessary, and 1 woman would die per 10,000 C-sections.

Although the decision to perform a C-section is made on a case by case basis, analysis of C-sections in the aggregate show us that the C-section rate CAN be too high. When you get to the point that you are saving 1 baby every 10 years, but killing 1 mother every year, the C-section rate is clearly too high. Why has the C-section rate risen so high in first world countries? The reason is that a tremendous premium has been placed on the life of each and every baby. That societal value is directly reflected in the rising number of lawsuits and monetary judgments for babies who die or are disabled during birth. That societal value is reflected in the fact that our judicial system operates as if we believe that if a C-section had even a remote chance of preventing the death or disability, that C-section should have been done, and because it wasn't done, the parents should be compensated.

Is that what we really believe? Is any number of unnecessary C-sections justified to save the life of one baby every decade or every century? How many maternal deaths are justified to save the life of one baby every decade or every century? Personally, I think the standard should be different. The number of unnecessary C-sections done to save one baby every decade is NOT unlimited. The number of maternal deaths is certainly not unlimited, and it is not even one to one. The standard for determining fault in an obstetric malpractice case should NOT be to show that a C-section could have prevented the baby's death or disability; the standard should be that the doctor could have reasonably foreseen (based on the evidence available) that a C-section was NECESSARY to prevent the baby's death or disability.

C-sections come with costs. We have not even talked about the financial costs, because, in my judgment, these are secondary. However, massive numbers of unnecessary C-sections cause unnecessary complications and unnecessary deaths. As the C-section rate rises, these unnecessary complications and unnecessary deaths rise from relatively trivial occurences, to occurences that far outweight the number of babies' lives saved. We, as a society, need to think about where we draw the line, because we, as a society, through our punishments and incentives, determine how high the C-section rate should be. Doctors are merely responding to society's wishes as expressed through our values and our legal system.


0 Old Comments: