Diversity in Clinical Trials

by Leah Cairns

You might assume that once a drug has gone through the long process of FDA approval, it is safe for anyone to use. For some people, however, that may not be true. Women and ethnic minorities have historically been underrepresented in clinical trials [vi], and as a result some drugs may be less effective or even dangerous for them to use. Although African Americans represent 12% of the United States population, they make up only 5% of all clinical trial participants. Only 1% of clinical trial participants were Hispanic, though they comprise 16% of the national population [i]. Some of these data can be attributed to confounding socioeconomic factors that limit the participation of certain subgroups in clinical trials, such as “insurance status, patient inconvenience costs, availability of transportation, distance to study site, and patient and family concerns about risk. [i]” However, even with these factors considered, case studies have found that a patient’s race, age and sex can play a more significant role in trial participation than their proximity to the study location and the other factors listed above [i][iv].

This is a particular problem in diseases of mental health. A report by the surgeon general in 2001 found that “among 10,000 participants included in randomized clinical trials for bipolar disorder, schizophrenia, depression and ADHD since 1986, ‘only 561 African Americans, 99 Latinos, 11 Asian American sand Pacific Islanders, and zero American Indians and Alaska Natives are available for analysis” [ix]. Disparities in schizophrenia treatment begin at diagnosis: Studies show that African Americans are diagnosed with schizophrenia at a disproportionately higher rate than white Americans (8). Further, it has been found that women, ethnic minorities and those over the age of 45 are more likely to receive first-generation anti-psychotic medicines, which have more side effects than newer medicines [v]. African Americans already have a greater risk of experiencing these side effects [iii], so this difference in prescription makes the problem even worse. An FDA webpage reports that a single Aripiprazole trial was comprised of 68% men and 32% women. By race, the patients were 47% white, 40% Black or African American, 13% Asian, and less than 1% each American Indian/Alaskan or Native Hawaiian/Pacific Islander. No differences in efficacy were found by sex or racial subgroups. There were, however, differences in risk for side effects. Men and African Americans had a higher rate of experiencing akathisia, the urge to move constantly. All patients were between 18 and 66 years of age; no information was provided as to the age breakdown [ii].

Inequitable research can lead to dangerous outcomes for those who are not represented in clinical trials. Drugs including chemotherapeutics, antiretrovirals, antidepressants, and cardiovascular medications have been withdrawn from market due to differences in drug metabolism and toxicity across race and sex [i]. Some efforts have been made to address this problem. In the late 1980s, as a result of a National Health Service Task Force on Women’s Health, policies were put in place at the NIH to encourage the inclusion of women and minorities in NIH-funded clinical studies. In the mid-1990s, this policy became law when congress passed the NIH Revitalization Act [vii]. Since then, the NIH has taken notice of this problem, and more women and minorities have been included in clinical trials. In 2007, a study investigating recent trials funded by the National Institute of Mental Health showed that data on sex were consistently being reported and enrollment was generally balanced by sex. However, data on race were not always reported, and if they were, enrollment of subgroups was not sufficient to perform rigorous analyses [vi]. If a particular subgroup is particularly susceptible to a disease or side effects of a drug, then that must be addressed directly with sufficient enrollment to fully investigate the issue at hand.

The FDA has introduced a new tool to help patients access and comprehend information about the demographics of clinical trials. In late 2014, they launched Snapshots, a webpage that reports on the demographics of clinical trials in easy-to understand language [ii]. Consumers can find out if trials found any differences based on sex, race, or age. Newly approved drugs should appear on this website within 30 days of FDA approval. As more demographic data are collected and reported, doctors and patients have greater access to this information while making healthcare decisions.

Although new FDA policies are requiring more specific reporting of the demographics of trial participants, current regulations do not require participation of specific subgroups in particular trials. More work and wider education on this topic is needed to ensure that all patients receive equitable healthcare options.



[i] Coakley, Meghan, et al. "Dialogues on diversifying clinical trials: successful strategies for engaging women and minorities in clinical trials." Journal of women's health 21.7 (2012): 713-716.

[ii] "Drug Trials Snapshots." U.S. Food and Drug Administration. U.S. Department of Health and Human Services, Web. 23 Nov. 2016.

[iii] Herbeck, Diane M., et al. "Variations in use of second-generation antipsychotic medication by race among adult psychiatric patients." Psychiatric Services 55.6 (2004): 677-684.

[iv] Kanarek N. F., et al. Geographic proximity and racial disparities in cancer clinical trial participation. J Natl Compr Canc Netw. 2010 Dec; 8(12):1343‐51.

[v] Kuno, Eri, and Aileen B. Rothbard. "Racial disparities in antipsychotic prescription patterns for patients with schizophrenia." American Journal of Psychiatry 159.4 (2002): 567-572.

[vi] Mak, Winnie WS, et al. "Gender and ethnic diversity in NIMH-funded clinical trials: Review of a decade of published research." Administration and Policy in Mental Health and Mental Health Services Research 34.6 (2007): 497-503.

[vii] “Monitoring Adherence to the NIH Policy on the Inclusion of Women and Minorities as

[viii] Subjects in Clinical Research: Comprehensive Report: Tracking of Clinical Research as Reported in Fiscal Year 2011 and Fiscal Year 2012” Bethesda, MD: Dept. of Health and Human Services, National Institutes of Health, Office of Research on Women's Health, 2013.

[ix] Strakowski, Stephen M., et al. "Ethnicity and diagnosis in patients with affective disorders." The Journal of clinical psychiatry 64.7 (2003): 747-754.

[x] US Department of Health and Human Services. "Mental Health: Culture, Race and Ethnicity-A Supplement to Mental Health: A Report of the Surgeon General Rockville, MD: Department of Health and Human Services." Substance Abuse and Mental Health Services Administration, Center for Mental Health Services (2001).