Modifications in drug adherence after switch to fixed-dose combination of perindopril/amlodipine in clinical practice. Results of a large-scale Italian experience. The amlodipine-perindopril in real settings (AMPERES) study

OBJECTIVE: The purpose of this study was to assess the changes in adherence to treatment, in patients who switched from perindopril and/or amlodipine as a monotherapy (single-pill therapy, SPT) or two-pill combinations to fixed-dose combination (FDC) therapy. METHODS: A large retrospective cohort study, in three Italian Local Health Units, was performed. All adult subjects who received at least one prescription of anti-hypertensive drugs between January 1, 2010 and December 31, 2014 were selected. The date of the first anti-hypertensive prescription was defined as the index-date (ID). For each patient, we evaluated the anti-hypertensive therapy and the adherence to treatment during the two 12-month periods preceding and following the ID. Changes in the level of adherence have been compared in patients who switched to the FDC of perindopril/amlodipine after the ID, as well as in patients who did not. RESULTS: A total of 24,020 subjects were initially included in the study. Subjects treated with the free dose combination switched more frequently to FDC of perindopril/amlodipine than subjects treated with SPT (p < .001). Adherence to treatment was found to be higher in the 3,597 subjects who switched to the perindopril/amlodipine FDC therapy, than in the 20,423 subjects who did not. A significant decrease in the number of concomitant anti-hypertensive drugs has been observed in patients treated with the same FDC. CONCLUSIONS: The results show that perindopril/amlodipine FDC increases the rate of stay-on-therapy and reduces the number of concomitant anti-hypertensive drugs in subjects previously treated with the same drugs as a two-pill combination or as SPT.