Discordant studies are part of the natural course of science, but there are other reasons for these wrong notes.
“Sometimes, we feel very small in our medical offices, recognizes Dr. Jean-Michel Calut, general practitioner in Puy-de-Dôme. I still remember the conflicting studies that came out on asbestos. On the one hand, the doctors of the Asbestos Standing Committee maintained that we had to learn to live with it, on the other hand, British studies warned of the dangers. And I, in my office, saw people in pain. At first, I was amazed. Afterwards, it was the disgust that dominated. When industrial interests are at stake, it is not uncommon for scientific truth to find it difficult to come to light.
But, this is not the only situation in which conflicting studies appear. Recently, two randomized studies on prostate cancer screening, published at the same time, gave discordant results. Nothing to do with any lobby, but “it’s disturbing, admits Dr Gaëtan Gentile, general practitioner in the Bouches-du-Rhône. I am annoyed because my patients go on the Internet and are aware of the results of these studies. “
Of course, the phenomenon is not new. In the early 2000s, the controversy over HRT was raging. The studies seemed to say everything and its opposite about possible risks of breast cancer, leaving women and doctors in bewilderment. For Dr Hervé Maisonneuve, former president of European Association of Scientific Editors, “Contradictory studies, there have always been and always will be. It is part of the normal course of science ”.
30,000 articles per month on Medline
However, other less respectable reasons explain these mistakes. First of all, the pace of publications has accelerated significantly. Today, the Medline database lists less than 30,000 articles per month. And yet, the major international journals publish on average only 7% of the articles submitted to them. To these major journals, we must add the electronic archives with free access where scientists can disseminate their communications in the form of pre-publications, but also the general public press which is increasingly seizing the results of international studies. The risk of reading discordant information is naturally increased. In addition, the big journals like the JAMA, the BMJ and the Lancet “are engaged in a real competition, explains Dr. Maisonneuve who belonged to the“ board ”of Jama. And the more there is the contradiction, the better it is for their notoriety. ”
Competition also exists between the researchers themselves. In urology, for example, the French hold the high priority to their American counterparts. This healthy rivalry may explain why the two studies were released at the same time. Another source of disagreement: the very nature of the studies. According to a researcher from the Belgian center for pharmacotherapeutic information, contradictory studies are mainly explained by the fact that certain sources of error, in particular bias and confounding variables, are more difficult to control in observational studies. However, the same subject is often the subject of randomized studies and observational studies.
Against the tide of dominant thought
These scientific round trips are not without consequences. As proof: the example of HRT. Of the two million women who took a hormonal replacement therapy in 2002, 32% stopped in 2003. However, in 2007, the French study Mission revealed that there was no higher risk of breast cancer in women. women followed by a gynecologist and treated with “French HRT”. Obstetricians remember the Hannah study, which went against other studies. It showed that the cesarean divided by 3 or 4 the deaths and serious pathologies of the newborn who presented by the breech. Six years after its publication, the Hannah study was withdrawn for incorrect methodology. But, for Professor Damien Subtil, head of the obstetrics pole of the CHRU in Lille, the damage was done. “If today we have a rate of caesarean sections that is a little too high, it is partly because of this study. Once results are published, it is difficult to go back. “In fact, if the results are against the current of dominant thought”, doctors find it difficult to accept them, analyzes Dr Pierre Durieux, lecturer at Paris Descartes University.
Training in critical article reading
To avoid being caught in turbulence and not to be carried away by the prevailing winds, the doctors have several parachutes at their disposal. For Dr. Gentile, his landmarks can be summed up in three letters: HAS and EBM (evidence based medicine). “In the case of studies on screening for prostate cancer, I cling to the recommendations of the HAS. And I am awaiting the conclusion of these studies, which are only preliminary ”. The High Authority for Health has also immediately reacted and informed the doctors that these new results should be “analyzed in detail”. And that “public policy in terms of screening will be based on all the contributions”, and in particular the future report of the Parliamentary Office for the Evaluation of Health Policies on individual screening for prostate cancer.
The other buoy that doctors can hang on to is called critical reading of articles. However, after fifteen years of battle, this discipline has finally made its official entry into the faculties. In the next national classifying examinations (ECN), students will, for the first time, have to take a critical reading test. “We teach students to be interested in the methodology of a study first. However, doctors tend to rush on the results of a study, ”explains Dr. Durieux. The new generation should therefore know how to read between the lines of studies, and find harmony where the results seem dissonant.
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