Real-World Adherence to Dihydropyridine Calcium-Channel Blockers: A Pharmacoepidemiologic Study

Low medication adherence contributes to uncontrolled cardiovascular (CV) risk.

This study investigated 12- and 24-month adherence, all-cause mortality and CV events in subjects receiving originator or generic dihydropyridine calcium-channel blockers (CCBs) as recorded in administrative databases from Local Health Units across several Italian regions.

We retrospectively analysed databases containing demographics and vital status, drug prescriptions, and hospital discharge diagnoses for more than 6 million individuals. Subjects receiving lercanidipine originator, generic lercanidipine, amlodipine originator, or generic amlodipine were included. Subjects with prior or occasional CCB use, inadequate follow-up time, chronic ischaemic heart disease or acute pulmonary heart disease, or switching between CCBs were excluded. Adherence was defined as a Proportion of Days Covered ≥ 80% at 12 and 24 months. Cox regression models estimated the association between treatments and a composite of all-cause mortality and CV events.

Adherence was assessed in 3,860 propensity-score-matched subjects (965/group), selected from 14,849 eligible subjects. Lercanidipine originator was associated with higher (p < 0.001) 12-month (43%) and 24-month (38%) adherence than generic lercanidipine (31 and 26%) and amlodipine originator (22 and 19%). The events analysis included 15,808 subjects. Compared with originator lercanidipine, originator amlodipine, generic lercanidipine and generic amlodipine were associated with 43%, 30% and 33% higher hazards of the composite outcome, respectively (corresponding 95% Confidence Intervals: 1.28-1.60, 1.10-1.55, 1.17-1.50).

Medium-term adherence was low across all treatments. Originator lercanidipine was associated with the highest adherence, with lower adjusted hazards of the composite outcome and all-cause mortality compared to the other treatments.