Should Clinical Trials Account for Social Determinants of Health?

August 01, 2019 - New data out of the Yale School of Medicine suggests that the social determinants of health may have an impact on clinical trial results, revealing that patients receiving their care in low-income areas face health disparities that patients in higher income areas do not.

The study, published in the Journal of the American Heart Association, utilized data from a hypertension clinical trial taking place from 1994 and 2002. The trial enrolled tens of thousands of patients and sought to examine the effectiveness of three hypertension drugs.

But when looking at care outcomes based on the social determinants of health, the Yale researchers learned something different. Where a patient receives their care – which can be tied to the societal factors a patient faces every day – will have an impact on their care outcomes, regardless of their treatment plans.

To draw that conclusion, the Yale researchers looked at data for 13,000 trial participants located in the continental United States. The researchers wanted to control for a certain hypertension management drug and specifically look at how care site and income level can impact outcomes.

“Typically in a randomized controlled trial where we try to equalize care across treatment arms and across clinical sites, we aim to isolate the effect of a medication to understand its efficacy,” senior study author Erica Spatz, MD, an associate professor of medicine at Yale School of Medicine, said in a statement.

“While medications are the mainstay of hypertension control, there are other factors that we need to pay attention to that are impacting blood pressure control, and the ultimate outcomes we care about - heart disease, stroke, hospitalization and longevity.”

Overall, 7.8 percent of the tested trial participants received their care in the lowest income sites and 37.6 percent receive care in the highest income sites. And these disparities led to vastly different care outcomes, Spatz and her team observed.

Patients receiving care in the lowest income sites were 25 percent more likely to die from any cause and 25 percent more likely to be hospitalized or die due to heart failure.

These participants were 86 percent more likely to develop end-stage renal disease (ESRD), and were 30 percent less likely to receive common treatments for heart attack or chest pain, such as a procedure that opens the blood vessels near the heart.

These results were of little surprise for the Yale researchers, who know that the social determinants of health can lead to health inequities.

However, findings were a wakeup call for designing clinical trials. The study results suggest that more consideration for the social determinants of health needs to be made when designing randomized control trials (RCT), which aim to control every aspect of care to truly test drug efficacy.

“Although the association of socioeconomic context with hypertension outcomes is well described, the differences in certain clinical outcomes in this study are notable because they occurred in the context of a large RCT, which typically affords participants equal access to resources for hypertension care by doing the following: (1) assigning them to standardized protocols in which study medications are provided free of charge and (2) providing specific guidelines for the intensification of medication and provision of follow‐up visits,” the researchers said.

Patients who received care in low-income areas tended to have lower healthcare utilization, either because they lacked the transportation and social support to get to the clinic or because they did not have adequate support in and exposure to self-management strategies.

And although a patient receiving care in a low-income area does not necessarily mean they themselves have a low income, it does suggest that the patient faces numerous social determinants of health that ultimately impacted their care outcomes.

These results came even as patients receiving care in low-income sites had fewer risk factors for hypertension issues. Patients receiving care in low-income areas were less likely to have a family history of heart disease, Type 2 diabetes, or a history of smoking. Instead, it may have been the social factors these patients experienced that influenced their ultimate care outcomes.

These findings suggest a need for a bigger focus on the social determinants of health when designing clinical trials, the researchers said.

“We observed disparities in blood pressure control, heart failure morbidity, ESRD, all‐cause mortality, and coronary revascularization across socioeconomic strata, even after controlling for medication treatment arm, demographics, and clinical characteristics,” the team concluded. “These findings underscore the importance of measuring socioeconomic context in RCTs and suggest the need to invest in strategies to mitigate socioeconomic disparities and achieve more equitable outcomes in the care of hypertension.”