Dementia clinical trials over the past decade: are women fairly represented?

Lack of progress in finding disease-modifying treatments for dementia may be due to heterogeneity in treatment effects among subgroups, such as by sex. Therefore, we investigated the characteristics of dementia trials completed in the last decade, with a focus on women's representation and sex-disaggregated outcomes.

Clinical trials on dementia completed since 2010 were identified from ClinicalTrials.gov. Randomised, phase III/IV trials with ≥100 participants were selected to quantify women's representation among participants, by computing the participation to prevalence ratio (PPR) and investigate whether sex-disaggregated analyses had been performed.

A total of 1351 trials were identified between January 2010 and August 2021 (429 520 participants), of which 118 were eligible for analysis of women's representation and sex-stratified analysis. Only 113 reported the sex of participants and were included in the analysis of women's representation. Of the 110 469 participants in these 113 trials, 58% were women, lower than their estimated representation in the global dementia population of 64%. The mean PPR was 0.90 (95% CI 0.86 to 0.94). Women's participation tended to be higher when the first or last authors of the trial report were women. Eight out of the 118 trials reported sex-disaggregated outcomes, and three of those found significant sex differences in efficacy outcomes. None of the trials reported screening failures or adverse events stratified by sex.

Overall, women and men were equally represented in dementia trials carried out over the past decade, but women's representation was lower than in the underlying dementia population. Sex-disaggregated efficacy and safety outcomes were rarely reported.