Association Between Self-Reported Medication Adherence and Therapeutic Inertia in Hypertension: A Secondary Analysis of SPRINT (Systolic Blood Pressure Intervention Trial)

Abstract

BACKGROUND: Therapeutic inertia (TI), failure to intensify antihypertensive medication when blood pressure (BP) is above goal, remains prevalent in hypertension management. The degree to which self-reported antihypertensive adherence is associated with TI with intensive BP goals remains unclear. METHODS AND RESULTS: Cross-sectional analysis was performed of the 12-month visit of participants in the intensive arm of SPRINT (Systolic Blood Pressure Intervention Trial), which randomized adults to intensive (<120 mm Hg) versus standard (<140 mm Hg) systolic BP goals. TI was defined as no increase in antihypertensive regimen intensity score, which incorporates medication number and dose, when systolic BP is ≥120 mm Hg. Self-reported adherence was assessed using the 8-Item Morisky Medication Adherence Scale (MMAS-8) and categorized as low (MMAS-8 score <6), medium (MMAS-8 score 6 to <8), and high (MMAS-8 score 8). Poisson regressions estimated prevalence ratios (PRs) and 95% CIs for TI associated with MMAS-8. Among 1009 intensive arm participants with systolic BP >120 mm Hg at the 12-month visit (mean age, 69.6 years; 35.2% female, 28.8% non-Hispanic Black), TI occurred in 50.8% of participants. Participants with low adherence (versus high) were younger and more likely to be non-Hispanic Black or smokers. The prevalence of TI among patients with low, medium, and high adherence was 45.0%, 53.5%, and 50.4%, respectively. After adjustment, neither low nor medium adherence (versus high) were associated with TI (PR, 1.11 [95% CI, 0.87–1.42]; PR, 1.08 [95% CI, 0.84–1.38], respectively). CONCLUSIONS: Although clinician uncertainty about adherence is often cited as a reason for why antihypertensive intensification is withheld when above BP goals, we observed no evidence of an association between self-reported adherence and TI.