Protection by inclusion: Increasing enrollment of women in cardiovascular trials

A Systematic Review of Female Participation in Randomized Controlled Trials of Post-Stroke Upper Extremity Rehabilitation in Low- to Middle-Income Countries and High-Income Countries and Regions

INTRODUCTION

Female participation is lower than males in both acute stroke and stroke rehabilitation trials. However, less is known about how female participation differs across countries and regions. This study aimed to assess the percentage of female participants in randomized controlled trials (RCTs) of post-stroke rehabilitation of upper extremity (UE) motor disorders in low-middle-income (LMICs) and high-income countries (HICs) as well as different high-income world regions.

METHODS

CINAHL, Embase, PubMed, Scopus, and Web of Science were searched from 1960 to April 1, 2021. Studies were eligible for inclusion if they (1) were RCTs or crossovers published in English; (2) ≥50% of participants were diagnosed with stroke; 3) included adults ≥18 years old; and (4) applied an intervention to the hemiparetic UE as the primary objective of the study. Countries were divided into HICs and LMICs based on their growth national incomes. The HICs were further divided into the three high-income regions of North America, Europe, and Asia and Oceania. Data analysis was performed using SPSS and RStudio v.4.3.1.

RESULTS

A total of 1,276 RCTs met inclusion criteria. Of them, 298 RCTs were in LMICs and 978 were in HICs. The percentage of female participants was significantly higher in HICs (39.5%) than LMICs (36.9%). Comparing high-income regions, there was a significant difference in the overall female percentages in favor of RCTs in Europe compared to LMICs but not North America or Asia and Oceania. There was no significant change in the percentage of female participants in all countries and regions over the last 2 decades, with no differences in trends between the groups.

CONCLUSIONS

Sufficient female representation in clinical trials is required for the generalizability of results. Despite differences in overall percentage of female participation between countries and regions, females have been underrepresented in both HICs and LMICs with no considerable change over 2 decades.

Improving representativeness in trials: a call to action from the Global Cardiovascular Clinical Trialists Forum

Participants enrolled in cardiovascular disease (CVD) randomized controlled trials are not often representative of the population living with the disease. Older adults, children, women, Black, Indigenous and People of Color, and people living in low- and middle-income countries are typically under-enrolled in trials relative to disease distribution. Treatment effect estimates of CVD therapies have been largely derived from trial evidence generated in White men without complex comorbidities, limiting the generalizability of evidence. This review highlights barriers and facilitators of trial enrollment, temporal trends, and the rationale for representativeness. It proposes strategies to increase representativeness in CVD trials, including trial designs that minimize the research burden on participants, inclusive recruitment practices and eligibility criteria, diversification of clinical trial leadership, and research capacity-building in under-represented regions. Implementation of such strategies could generate better and more generalizable evidence to reduce knowledge gaps and position the cardiovascular trial enterprise as a vehicle to counter existing healthcare inequalities.