Psychotropic polypharmacy in Australia, 2006 to 2015: a descriptive cohort study

To describe psychotropic polypharmacy in Australia between 2006 and 2015.

We used pharmaceutical claims from a national 10% sample of people with complete dispensing histories to estimate the annual prevalence of the combined use (overlap of >60 days exposure) of ≥2 psychotropics overall and within the same class or subclass (class and subclass polypharmacy). We also estimated the proportion of polypharmacy episodes involving one, two, three and four or more unique prescribers.

The prevalence of class polypharmacy between 2006 and 2015 in people dispensed specific psychotropic classes was 5.9-7.3% for antipsychotics, 2.1-3.7% for antidepressants and 4.3-2.9% for benzodiazepines. The prevalence of antipsychotic polypharmacy was higher than expected given the prevalence of antipsychotic exposure and combinations of sedating agents were notably common. Overall, 26.7% of polypharmacy episodes involved multiple prescribers but having multiple prescribers occurred more frequently for class and subclass polypharmacy and people with four or more concomitant psychotropics.

Psychotropic polypharmacy is common, despite limited evidence of risks and benefits. Increases in polypharmacy with multiple prescribers may be due to poor communication with patients and between health care professionals.