Trends and Predictors of Antihypertensive Medication Adherence in Commercially Insured Adults under 65 (2018-2023)

Understanding class-specific antihypertensive adherence is crucial for optimizing hypertension management. This retrospective cohort study analyzed adherence to antihypertensive medication among commercially insured adults (18-64 years) from 2018 to 2023 using Merative MarketScan data. Adherence was defined as the proportion of days covered (PDC) ≥ 80%. Among 2 770 855 hypertensive patients with single-pill therapy, the majority were older (43% aged 55-64 years) and predominantly male (53%). The South had the highest prevalence of hypertension (53%). Overall adherence improved significantly from 56.61% in 2018-2019 to 75.55% in 2022-2023 across all medication classes. Patients receiving angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACEi/ARB) combination therapies had the highest adherence rate (79.18%), while diuretics (67.58%) and "Other Drugs" (57.38%) had the lowest in 2022-2023. Logistic regression showed that younger patients (18-34 years) were significantly less adherent than older adults (OR = 0.434, 95% CI: 0.420-0.448). Males were more likely to adhere than females (OR = 1.142, 95% CI: 1.129-1.156). Regional variations were notable, with patients in the Northeast exhibiting 15% higher adherence than those in the West. Insurance types also influenced adherence, with managed care plan enrollees showing better adherence than those in fee-for-service plans (OR = 1.165, 95% CI: 1.151-1.179). Surprisingly, prescription refill monitoring reduced adherence, decreasing odds by 52% (OR = 0.482, 95% CI: 0.470-0.490). Monotherapy and combination therapy users differed significantly across all demographics (p < 0.0001). Higher comorbidity burden correlated with lower adherence, with diabetes being most prevalent among users of diuretics (12.88%), beta-blockers (12.8%), and other antihypertensives (26.01%). These findings highlight the multifaceted barriers to antihypertensive adherence and emphasize the need for targeted interventions that address medication-specific and patient-specific factors.