Sunday, March 25, 2007

MANA and publication bias

You may recall that I have written about the fact that MANA (Midwives Alliance of North America) has collected data on all homebirths by certified midwives in the past 5 years, but has not released that data (Why is MANA hiding its data?). The only way to get access to the data is to show that you will "use the data for the advancement of midwifery".

According to the NARM (North American Registry of Midwives) Summer 2006 Bulletin the only way you can see the data is if you are a midwifery organization whose members have contributed personal statistics to the database. Even then, the procedure is complicated and you must sign a "Non-disclosure Agreement which prohibits inappropriate use of the data..."

There is a term that describes this type of behavior. It is called publication bias, and it is considered unethical behavior.

When doctors and other health professionals try to decide on an appropriate treatment, they draw on the existing medical literature to determine the safety and efficacy of various options. Obviously, this review of the literature will be influenced by the content and quality of studies on the subject under investigation. What is less obvious is that such a review will be affected by content and quality of research that has never been published.

There are two main types of publication bias: one is the bias of journal editors to publish papers that report positive results, the other is the publication bias that occurs when researchers fail to publish results that are contrary to what they would like to show. MANA, by refusing to make its results publicly available, is committing this second type of publication bias.

MANA did not pioneer this type of publication bias. That was done by the drug companies. They have a vested interest in publishing studies that promote the use of their medications and failing to publish study results that call the efficacy or safety of their drugs into question. The classic case of this type of publication bias is Vioxx. Merck had commissioned and paid for a study that showed Vioxx had dangerous side effects. Merck did not publish these results and did not share them with physicians.

Ian Chalmers, of the National Perinatal Epidemiology Unit in Oxford, wrote in a JAMA article that Underreporting research is scientific misconduct:
Substantial numbers of clinical trials are never reported in print, and among those that are, many are not reported in sufficient detail to enable judgments to be made about the validity of their results. Failure to publish an adequate account of a well-designed clinical trial is a form of scientific misconduct that can lead those caring for patients to make inappropriate treatment decisions. Investigators, research ethics committees, funding bodies, and scientific editors all have responsibilities to reduce underreporting of clinical trials.
Chalmers is referring here to clinical trials, but I believe that the same principle applies to collections of statistics or adverse outcomes.

What is interesting about MANA's behavior is that they are quite open about their determination to commit publication bias. By publicly claiming that data about homebirths can only be used "for the advancement of midwifery", they are openly acknowledging that they are willing to use this unethical tactic to influence scientific knowledge about the safety of homebirth.

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