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Systematic Review of Gender Bias in the Clinical Trials of New Long-Acting Antipsychotic Drugs

Santos-Casado, María, Psychiatrist MD*; García-Avello, Adela, PharmD

Journal of Clinical Psychopharmacology: May/June 2019 - Volume 39 - Issue 3 - p 264–272
doi: 10.1097/JCP.0000000000001041
Review Article

Purpose/Background This article evaluates gender bias in the published clinical trials of new long-acting antipsychotics.

Methods/Procedures We conducted a review of controlled clinical trials of the new prolonged-release antipsychotics (aripiprazole, risperidone, or paliperidone) for the treatment of schizophrenia published in MEDLINE over the last 10 years and available in full text in English. The study followed the corresponding international recommendations.

Results We identified 132 trials, and of these, 40 met the inclusion and exclusion criteria. We found that only 36.41% of the total patients were women. The separate analysis of the main variable between the subpopulations of men and women was carried out in only 6 of the 40 works included. In contrast, in 15 trials, this analysis was performed on secondary variables, generally related to safety. Only 3 of the 40 trials discussed the results separately according to sex.

Conclusions The clinical trials of long-acting atypical antipsychotic drugs show a far-from-negligible gender bias. Women are underrepresented, and the main and secondary variables are not analyzed separately according to gender. This is despite international recommendations establishing these criteria as part of a package of minimum requirements for meeting scientific validity and making results apt to extrapolate to the general population of patients.

From the *Psychiatry Department, University Hospital of Jerez, Jerez de la Frontera; and

Hospital Pharmacy Department, University Hospital Virgen del Rocío, Seville, Spain.

Received July 23, 2018; accepted after revision January 22, 2019.

Reprints: María Santos-Casado, Psychiatrist MD, Hospital Universitario de Jerez, Ronda de Circunvalación, s/n, 11407 Jerez de la, Frontera, Cádiz, Spain (e-mail:

Both authors guarantee the accuracy, transparency, and integrity of the data and information contained in the study. No relevant information has been omitted, and all discrepancies between authors have been adequately resolved and described.

Authorship Contributions: M.S.-C. had the original idea. Both authors worked out the design of the methods. A.G.-A. carried out the bibliographic search, and both authors selected the works to be included and then analyzed their characteristics. A.G.-A. processed the data and M.S.-C. wrote the first draft, but both authors are responsible for the final text.

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