Regulatory effect of decreasing therapeutic duplication of respiratory drugs using a prescription database between 2012 and 2015.

Duplicative drug use increases the risk of adverse drug reactions and expends healthcare resources unnecessarily. No epidemiological evidence of the prevalence of therapeutic duplication (TD) involving respiratory system drugs exists. Therefore, we describe the prescription patterns of these drugs and estimate changes in TD rates following implementation of a new regulation in 2013. A time-series analysis using national healthcare data was conducted, involving eight classes, and patients prescribed any of these drugs between 2012 and 2015. We used two definitions of TD; duplicative prescriptions overlapped for more than 30 days by the same prescriber and for more than 1 day by different prescribers. We calculated relative and absolute difference in TD rates after the regulation. TD by the same prescriber decreased for respiratory drugs of six classes, but increased more than 10% for antihistamines (+10.28, +0.05). TD by a different prescriber decreased only for xanthine bronchodilators, but increased more than 10% for beta-receptor agonists (+27.07, +1.42), leukotriene receptor antagonists (+16.10, +0.44), cough suppressants (+15.64, +0.52), mucolytic agents (+11.16, +0.67). The 2013 regulation regarding respiratory drugs did not have the anticipated effect of reducing TD prevalence; more effective interventions are needed.