The influence of the Pharmaceutical Benefits Scheme (PBS) on inappropriate prescribing in Australian nursing homes.

Objectives: To determine the prevalence of inappropriate prescribing, defined by applying modified Beers' criteria, and to examine the influence of the Pharmaceutical Benefits Scheme (PBS), Australia's national scheme for subsidising medicines, on inappropriate prescribing.
Methods: Cross-sectional survey of nursing home records, including 7-days data from medication charts.
Setting: Fiveteen randomly selected nursing homes (998 residents) in Southeast Queensland and Northern New South Wales, Australia.
Main Outcome Measures: The prevalence of inappropriate prescribing as defined by modified Beers' criteria and its correlation with PBS restrictions.
Results: 18.5% of residents were ordered one or more inappropriate medications, and 1.5% of residents were ordered two or more. The level of PBS restriction and the percentage of residents ordered a medication were highly correlated (p = -0.87, P < 0.001). Medications in Beers' criteria that were not listed (subsidised) on the PBS were not ordered for any resident. PBS medicines with subsidies restricted to certain populations or indications were ordered for 0% to 0.1% of residents. Dextropropoxyphene, diazepam, amitriptyline and methyldopa were the only medications in Beers' criteria prescribed to more than 0.5% of residents. Dextropropoxyphene was only subsidised for war veterans, with a caution warning of its potential to cause drug dependence, while diazepam, amitriptyline and methyldopa were listed on the PBS without any subsidy restrictions.
Conclusion: Increases in the level of PBS restriction were associated with decreases in the prevalence of inappropriate prescribing, The targeting of drug subsidies to reduce inappropriate prescribing warrants further investigation.