Habit
strength for taking medication is associated with medication adherence. However,
habit strength is typically measured via self-reports, which have limitations.
Objective sensors may provide advantages to self-reports. To
evaluate whether habit-strength metrics derived from objective sensor data
(MEMS® Caps; AARDEX Group) are associated with self-reported habit strength and
adherence (objective and self-reported) and whether objective and self-reported
habit strength are independently associated with adherence. Patients
(N = 79) on oral medications for type 2 diabetes completed self-reports of habit
strength and medication adherence and used MEMS® Caps to take their prescribed
medication for one month. MEMS® Caps data were used to create five objective metrics
of habit strength (e.g., individual-level variance in pill timing) and quantify
medication adherence (% days correct dosing). Consistency
in behavior from week to week (versus across each day) had the greatest
association with self-reported habit strength (r(78) = 0.29, p = 0.01),
self-reported adherence (r(78) = 0.32, p = 0.005), and objective adherence (r(78) = 0.61, p < 0.001). Objective and self-reported habit strength were
independently associated with adherence. Weekly
pill-timing consistency may be more useful than daily pill-timing consistency
for predicting adherence and understanding patients’ medication-taking habits.
Self-reports and objective metrics of habit strength may be measuring different
constructs, warranting further research.
