How does prescribing for antihypertensive products stack up against guideline recommendations? An Australian...

We describe choice of first-line antihypertensive drug therapy and uptake of fixed-dose combinations (FDCs) in Australia, and investigate the impact of initiation on FDCs and other non-recommended first-line therapies on treatment discontinuation.

This was a population-based retrospective cohort study using a random 10% sample of persons dispensed an Australian Pharmaceutical Benefits Scheme listed medicine from 1 July 2005 to 30 June 2014. The primary outcomes were adherence to Australian recommendations at initiation of antihypertensive therapy, discontinuation of initial therapy and discontinuation of any therapy in the first year after initiation.

In our sample of 55 937 persons initiating therapy, 42.0% did so outside Australian recommendations, including not initiating on recommended monotherapy (26.3%) and not initiating on the lowest recommended dose (30.6%). Only 1.7% of individuals who were dispensed an FDC established therapy on the free combination regimen (as recommended) prior to switching. After adjusting for covariates, persons initiating on non-recommended monotherapy (OR = 2.64, 95% CI 2.47-2.83) or FDCs of two or more antihypertensives (OR = 1.42, 95% CI 1.30-1.55), were more likely to discontinue all antihypertensive drug treatment in the first year compared to persons initiating on recommended monotherapy.

More than half of antihypertensive initiators conformed to Australian guidelines. Initiation on FDCs and other non-recommended treatments was associated with lower persistence on antihypertensive therapy in the first year. Long-term effectiveness and outcomes may be enhanced by initiating with low dose monotherapy.