Does Concordance with Fixed-Dose Combination (FDC) Treatment Guidelines Improve Persistence? An Australian Population Based Cohort Study.

Background: In Australia, FDC products are not recommended for first-line hypertension therapy. While the use of FDCs has increased substantially in recent years, there is little information about how their use in routine care compares to Australian guidelines.Objectives: We investigated how first-line antihypertensive therapy followed Australian recommendations, and the impact of initiation outside recommendations on treatment discontinuation in the first year.Methods: We performed a population-based retrospective cohort study using dispensing data for a 10% sample of Australians (2005-2014). Among incident users of antihypertensive medicines, we identified whether the choice of antihypertensive adhered to Australian recommendations. We used logistic regression to determine whether adhering to guidelines at initiation was associated with discontinuation of initial therapy, and discontinuation of any therapy in the first year of treatment.Results: In our sample of 55 937 persons initiating therapy, 5.0% initiated on a FDC. Persons initiating FDCs had a higher median initiating defined daily dose (DDD) for angiotensin-converting-enzyme inhibitors/angiotensin II receptor antagonists (2 vs 1, p<0.001), but a lower median DDD for thiazide diuretics (0.5 vs 1, p