Trials investigating pharmacologic interventions for low back pain tend to underreport demographic data, and those that do include these data have patient samples that are not representative of the general US population, according to study results published in The Journal of Pain.
It is of major concern that marginalized groups are underrepresented in randomized controlled trials (RCTs) of pain treatment. Research shows that these groups often experience more severe pain and have a higher frequency of pain conditions. In addition, they receive fewer benefits from clinical research, undergo suboptimal treatments, and experience unstudied adverse events. To address this issue, researchers conducted a systematic review to identify potential disparities in sample representation in pharmacologic interventions for lower back pain. Following PRISMA guidelines, they searched for relevant English-language RCTs in Embase, MEDLINE, and CINAHL in December 2021. The review included 139 RCTs (59 with a US location and 80 without a US location) evaluating pharmacologic interventions for low back pain.
Among the 139 trials, 81.3% reported data on sex or gender categories but none assessed sexual or gender minority categories. There was very little variation in the percentage of women participating in trials conducted within the US (52.5%) vs outside the US (54.2%). Industry-sponsored trials had the highest percentage of women participants, and government-sponsored trials had the lowest. Most trials (71.2%) excluded pregnant or lactating individuals.
Only 7.5% of clinical trials conducted outside the US collected information on race or ethnicity, whereas 47.5% of trials conducted within the US did so. Among trials within the US that collected information regarding race or ethnicity, 35.7% collected data on both race and ethnicity, 42.8% collected data on only race, and 21.5% collected only data on race but included Hispanic ethnicity as a category. However, the data showed a significant underrepresentation of Asian American and Pacific Islander, Hispanic/Latinx, and American Indian or Alaskan Native participants, compared with the representation of these groups in the US population. In contrast, White participants were overrepresented, with 72.5% inclusion across extracted trials vs 71.0% in the US population. Black participants were also overrepresented, with 18.8% inclusion across extracted trials vs 14.2% representation in the US population.
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In conclusion, while progress has been made in some areas, considerable work remains in ensuring truly representative and inclusive RCTs in LBP.
While patients between 60 and 70 years of age are being included more frequently in clinical trials, there is still a significant gap in terms of including patients older than 75 years, regardless of funding types. Industry trials in the US are more likely to include older adults (with an upper age cutoff of 75 to 80 years) than government-funded trials in the US (with an upper age cutoff of 55 to 70 years). None of the academic and government-funded trials met the 2012 updated recommendation of the US Food and Drug Administration on including people aged 75 years and older in RCTs.
Study limitations include comparison of sample characteristics with the diversity observed across the US, whereas these comparisons may be improved in future research by instead examining the diversity of the region for each study; use of the US Census Report for comparisons of racial and ethnic composition; and lack of inclusion of certain patient characteristics that may impact clinical trial participation (such as income, education, geographic location, and access to health care resources). Additionally, it is possible that patients with lower back pain are not representative of the general US population.
The researchers emphasized, “In conclusion, while progress has been made in some areas, considerable work remains in ensuring truly representative and inclusive RCTs in LBP.” They added, “Addressing these disparities is central to delivering equitable, effective, and personalized health care for all. Standardizing demographic data reporting and integrating community-based participatory research methods can help foster inclusive research practices.”