A systematic review of randomized clinical trials (RCTs) of lipid-lowering therapies (LLTs) found women and older adults are consistently underrepresented, despite ongoing efforts to increase inclusion of these populations, according to a study published in JAMA Network Open.

For this analysis, researchers selected primary and secondary prevention studies of LLTs with at least 1,000 participants conducted between 1990 and 2019 with follow-up of at least one year. In total, 60 trials with 485,409 participants were included, to examine the prevalence of women and older (age >65 years) participants, temporal trends in their participation, representations of women in RCTs relative to disease burden (using the participation-to-prevalence ratio [PPR] metric) and trends in reporting outcomes based sex and age.

Looking at women, representation overall was 28.5%, increasing from 19.5% for the period of 1990 to 1994 to 33.6% for the period of 2015 to 2018. Some common factors limiting the representation of women in RCTS was the inclusion of only postmenopausal women or surgically sterile women and the exclusion of pregnant and lactating women.

Compared with their disease burden, women were underrepresented in lipid RCTs of diabetes (PPR, 0.74); heart failure (PPR, 0.27); stable coronary heart disease (PPR, 0.48); and acute coronary syndrome (PPR, 0.51).

Regarding older adults, only 23 RCTs with 263,628 participants reported the proportion of older participants. Their overall representation was 46.7%, a numerical increase from 31.6% to 46.2% for the periods of 1995 to 1998 and 2015 to 2018.

Only 53% of trials reported outcomes according to sex and only 36.6% according to older adults, with no improvement found over time.

Noting there was only modest improvement in enrollment over time, likely reflective of regulations by the U.S. Food and Drug Administration, they add there are no legal or regulatory mandates requiring a specific proportion of participants based on sex or age.

"Therefore, practical steps should be undertaken to develop new strategies to achieve optimal recruitment of these subsets of the population in RCTs, and investigators should be encouraged to report results based on these subgroups to enhance generalizability of their results," the authors write.

Clinical Topics: Acute Coronary Syndromes, Dyslipidemia, Geriatric Cardiology, Heart Failure and Cardiomyopathies, Prevention, Atherosclerotic Disease (CAD/PAD), Lipid Metabolism, Acute Heart Failure

Keywords: ACC Advocacy, Female, Aged, Acute Coronary Syndrome, Secondary Prevention, Follow-Up Studies, Coronary Artery Disease, Heart Failure, Diabetes Mellitus, Type 2, Lipids, Longitudinal Studies

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