Women and minorities under-represented in trials

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Enrolment demographics published in many US vascular surgery randomised control trials (RCTs) under-represent women as well as race or ethnic minorities, according to a new study published in the Society for Vascular Surgery’s August 2009 issue of the Journal of Vascular Surgery.

According to the research team from Brigham and Women’s Hospital and Harvard Medical School in Boston, these groups of patients are generally under-reported in trials for aortic aneurysms, carotid artery stenosis and peripheral artery disease.


Their retrospective study was comprised of United States-based RCTs from 1983 through 2007 and focused on three broadly defined vascular procedures – aortic aneurysm repair, carotid revascularisation, and lower extremity revascularisation.


Data was collected and analysed with regard to gender and ethnicity, study parameters, funding source and geographic region. The Nationwide Inpatient Sample database also was analysed to obtain group-specific procedure frequency as an estimate of procedure frequency in the general population.


“Seventy-seven studies were reviewed and 52 met our inclusion criteria,” said Louis L Nguyen, from the division of vascular surgery and the Center for Surgery and Public Health at Brigham and Women’s Hospital. “Of these, only 85% reported gender and 21% reported ethnicity. Reporting of ethnicity was strongly associated with larger (more than 280 subjects) multicentre and government-funded trials.”

He added that women were disproportionately under-represented in RCTs for all procedure categories: aortic aneurysm repair, 9% vs. 21.5%; carotid revascularisation, 30% vs. 42.9%; and lower limb revascularisation, 22.4% vs. 41.3%. Minorities were under-represented in aneurysm studies (6% vs. 10.7%) and carotid studies (6.9% vs. 9.5%), while they were over represented in lower extremity revasculiration studies (26% vs. 21.8%).


Nguyen said that minority ethnicity and female gender are particularly under-reported and under-represented in small, non-government funded and single-centre trials; and therefore, the generalisability of some trial results may not be applicable to these populations. “We recognise that under-representation of some demographic groups in RCTs may be an unintentional or unavoidable consequence of conducting safe, timely and much-needed trials,” added Nguyen. “Though well-studied in other fields, balanced enrollment of patients with relevant demographic characteristics in vascular surgery RCTs is not well-known.”


“Our findings call into question the applicability of current evidence-based medicine for women and race/ethnic minorities with vascular disease,” said Nguyen. “The RCTs are considered to be the strongest level of evidence in evidence-based medicine because random assignment of patients in one of two treatment groups allows for unbiased analysis, and because they have to meet strict scientific, ethical, and regulatory standards in order to yield meaningful results while preserving patient safety.”


Researchers added that an increased effort to achieve a more balanced demographic representation in clinical trials may lead to results with greater applicability to the broader population as well as reduce disparities seen in the diagnosis and treatment of vascular disease.


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