Defining Meaningful Change in Antihypertensive Medication Adherence in Adults with Established Hypertension

The authors determined the within-person minimal detectable change (MDC) in antihypertensive medication adherence using the 4-item Krousel-Wood Medication Adherence Scale (K-Wood-MAS-4) administered twice over 13 to 22 days among 204 adults taking antihypertensive medication. They applied the MDC to 913 participants in a cluster-randomized trial of strategies to improve blood pressure (BP) control to determine the proportion with a decline in adherence over 6 months and its association with BP outcomes. A 2-point or greater change in K-Wood-MAS-4 seems to represent meaningful change. Among trial participants, 5.9% experienced a decline in adherence using this threshold for change, and decline in adherence was associated with higher BP and higher prevalence of uncontrolled BP.