Evaluation of antidepressants: “The challenge is to know what to measure or not in tests”

The Psychiatrist and Doctor of Public Health Astrid Chevance returns to the current criteria for selecting potential treatment of depression and the difficulty of defining the effectiveness of a drug.

Interview by words collected by, Nathalie Brafman and Pascale Santi

Astrid Chevance is a psychiatrist and doctor of public health in the Methods team (Inserm, University of Paris, AP-HP) within the Research Center in Epidemiology and Statistics (CRESS), led by Philippe Ravaud. Specialist in depression, its research area is assessing treatment.

How are antidepressants assessed today?

The first antidepressants and their evaluation appeared in the late 1950s. From the 1970s, psychotherapy and various brain stimulation techniques were evaluated, and more recently all types of interventions (light therapy, physical activities , food supplements, etc.). These assessments condition market access, reimbursement or clinical practice recommendations. For example, concerning the reimbursement of a medication, it must have proven that the tested drug does better than those who are already in circulation, or if it does as well, then it must be shown that it has fewer side effects Or that it is cheaper. In short, that it will improve medical care.

The challenge is to know what to measure or not in the tests. For depression, what is complicated is precisely to agree to define the effectiveness of a treatment and its usefulness.

What criteria are retained?

Currently, the criterion of main judgment required for studies of access to the antidepressant market can either be the severity scale of Hamilton’s depression, or Madrs (Montgomery-Asberg Depression Rating Scale). These scales aggregate very different symptoms in one score. That of Hamilton includes seventeen items that measure sadness, insomnia, suicidal ideas … However, each item weighs the same weight in the final score. Suicidal ideas (only one item) have less importance than insomnia (three items), which can be questionable. In addition, controversies exist on the relevant thresholds. Should a drug improve the patient’s feeling on three points of the scale to be tried clinically interesting or on five points?

Based on these two scales, antidepressants have indisputably proven their proofs. From a clinical point of view, in the trials, the effect is not huge, but it is present. This is demonstrated in meta-analyzes [studies which aggregate the results of previous studies]. The clinical interpretation of this effect size remains delicate due to the scales used.

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