Persistence of antihypertensive drug use in German primary care: a follow-up study based on pharmacy claims data.

Purpose: To study drug persistence for antihypertensive treatment considering typical patient behaviour including extended drug holidays or irregular repeat prescriptions.
Methods: We used prescription data from a German statutory health insurance to follow up patients for 4 years. Medication persistence was defined as the continued use of a specific drug class, therapy persistence as the continued use of any antihypertensive drug. We applied 2 different interval criteria within which a repeat prescription had to be issued: 180 and 360 days.
Results: A total of 9,513 patients started an antihypertensive therapy between 2006 and 2008. Applying the 180-day (360-day) interval criterion, 28 % (66 %) of the patients starting therapy with a beta-blocker were still medication-persistent after 4 years. The rates were similar for angiotensin-II receptor blockers (ARBs; 30 % and 69 % respectively) or angiotensin-converting enzyme (ACE) inhibitors (28 % and 61 % respectively). Looking at therapy persistence, these rates were 44 % (79 %) when an ACE inhibitor was the initial drug, 46 % (82 %) for ARBs. On average, even of those who were defined as therapeutically persistent with the 360 days criterion, half received a repeat prescription within 96 days, three quarters within 131 days-with a median supply of 1.2 units per day and 1.25 defined daily doses.
Conclusion: By applying more patient-orientated criteria, we found that many patients were therapy-persistent and received a prescription at the appropriate time. Therapy persistence was nearly independent of the initial agent; thus, drug persistence may not be an argument in favour of choosing a certain drug as a first-line option.