Nearly one-third of insured adults with diagnosed hypertension were nonadherent to their antihypertensive medications in 2015, according to a report published Nov. 4 in Hypertension.
Data from 2015 tells us that 32.1% of American adults had hypertension that year, but just 48.6% of those people had controlled blood pressure. Despite the established importance of therapies like ACE inhibitors and beta-blockers, first author Tiffany E. Chang, of the National Center for Chronic Disease Prevention and Health Promotion at the CDC, and colleagues said, there’s no single databank in the U.S. that provides information on nonadherence across all age groups and insurance plans.
“Although adherence to antihypertensive therapy has been associated with decreased risk of cardiovascular disease morbidity and mortality, prior studies have found that adherence is suboptimal,” Chang et al. wrote. “For example, in a national study of Medicare Part D beneficiaries, roughly one-quarter of adults aged [65 and up] were nonadherent to antihypertensive medications, with disparities by member characteristics and geography.”
The team undertook an analysis of 2015 prescription claims data from Medicare Part D and three IBM MarketScan databases, including Commercial, Medicaid and Medicare Supplemental. Using that data in conjunction with findings from the National Health Interview Survey, they aimed to calculate nonadherence rates among all U.S. adults aged 18 and up.
Chang and colleagues included 23.8 million hypertensive adults in their study who filled a total of 265.8 million prescriptions for antihypertensive drugs in 2015. Nonadherence seemed to differ by insurance type—it was highest for Medicaid members (55.4%) and lowest for Medicare Part D beneficiaries (25.2%).
The team reported that the overall weighted national nonadherence rate in their study was 31%, with men, older adults and fixed-dose combination medication users more likely to adhere to a drug regimen than women, younger adults and fixed-dose combination medication non-users, respectively. People who picked up their medications in retail-only settings also exhibited greater nonadherence (30.7%) than those who received their meds in the mail (19.8%).
The idea of increasing access to medication through mail orders isn’t new—several studies have credited the method with patients’ increased adherence to their drug regimens. But Chang et al. argued that while mail-order pharmacies are undoubtedly convenient, they remove a critical barrier between patients and pharmacists, cutting out communication that’s historically helped patients better understand their medication routines and how to stick to them.
There were a handful of limitations to the study, the authors said, one being that the team’s estimated numbers of nonadherent adults are likely conservative and another being the fact that their study sample isn’t nationally representative.
“Public health, clinical organizations and others striving to improve hypertension control can adopt a similar standardized strategy to estimate medication nonadherence in a population,” Chang and colleagues wrote. “This will help identify and monitor populations at high risk for nonadherence and inform the use of targeted interventions, which may ultimately support improved blood pressure control.”