Enrollment of Minorities in Fibromyalgia Trials Remains Low


Among the fibromyalgia studies conducted in the US and Canada over the past 22 years, 90% of participants identified as White.

Enrollment of Minorities in Fibromyalgia Trials Remains Low

Reza Zamani, PhD

Credit: University of Exeter Medical School

Among trials performed in the United States and Canada, a significantly lower number of ethnic minorities were included in pharmaceutical studies for fibromyalgia compared with White participants, according to research published in The International Journal of Environmental Research and Public Health.1

The under-representation of ethnic minorities in Western trials has gained increasing recognition in recent years as ethnicity has also been shown to impact the outcome, pathogenesis, and prevalence of certain chronic conditions. As genetic differences between ethnicities can affect the metabolism of some drugs, it is critical to enroll more ethnically diverse groups to analyze how this could affect the tolerability, efficacy, and optimal dosage among patients with different backgrounds.2

“Globally, the representation of White participants in clinical trials is higher than all other ethnic groups, primarily due to the majority of trials being conducted in Western countries; however, multiple factors hinder non-White participant recruitment to trials,” wrote co-lead investigator Reza Zamani, PhD, honorary associate professor at the University of Exeter Medical School. “For example, in some communities, these include poor health literacy (and by extension, health research) and mistrust of scientists due to historically unethical practices, such as the Tuskegee experiment. Additionally, within Western countries, socioeconomic deprivation is more common in non-White groups.”

Ethnic diversity, longitudinal changes in non-White participant proportions, and the likelihood of discontinuation between trial stages were assessed using a database search of relevant trials published on PubMed, Scopus, Web of Science, and the Cochrane Library between 2000 and 2022.

Ultimately, 58 fibromyalgia trials were included in the analysis, of which 56 recruited new participants. Most trials (76.8%, n = 43) reported demographic information, including the proportion of White participants, which ranged from 77.4% to 100%. Of the studies performed in the United States and Canada, an average of 90.1% of subjects identified as White. These percentages were slightly higher in trials which exclusively recruited patients living in the United States (90.6%).

An additional longitudinal analysis of 27 multicenter trials revealed 10% of total participants were non-White. No changes in the proportion of non-White participants were observed during the 22-year timespan. Between 4 initial trial stages and 4 continuation stages, retention rates were similar among both White and non-White subjects (49.0% and 51.6%, respectively).

Investigators mentioned limitations such as excluding otherwise eligible studies due to issues including journal access, potential database search errors, and a lack of ethnicity demographics information in their metadata. Despite this, they believe it is unlikely these issues would have significantly affected the findings. Additionally, the number of fibromyalgia trials has marginally reduced since the later 2010s, findings may be slightly dated and not representative of recent changes advocating for the purposeful recruitment of non-White participants. Finally, the results are restricted to pharmacological fibromyalgia research performed in the United States and Canada. Therefore, future reviews should analyze the ethnic diversity in other Western countries in the United Kingdom and Europe as well as assess if enrollment patterns are similar for non-pharmaceutical treatment interventions.

“This review adds to the culminating literature highlighting inadequate ethnic diversity in clinical research,” investigators concluded. “Furthermore, our findings indicate that the proportion of non-White participants in clinical trials in the United States should be more than double the current figure. Since the fibromyalgia studies we identified investigated the repurposing of existing treatments, further reviews could investigate whether the proportions of ethnic minorities are lower in these types of trials compared with trials testing novel pharmaceuticals.”


  1. Henley P, Martins T, Zamani R. Assessing Ethnic Minority Representation in Fibromyalgia Clinical Trials: A Systematic Review of Recruitment Demographics. Int J Environ Res Public Health. 2023;20(24):7185. Published 2023 Dec 15. doi:10.3390/ijerph20247185
  2. Burroughs, V.J.; Maxey, R.W.; Levy, R.A. Racial and ethnic differences in response to medicines: Towards individualized pharmaceutical treatment. J. Natl. Med. Assoc. 2002, 94 (Suppl. S10), 1–26.
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