Impact of legislation and a prescription monitoring program on the prevalence of potentially inappropriate prescriptions for monitored drugs: a time series analysis

Background — The researchers assessed the impact of new legislation and a centralized prescription monitoring system (implemented November 2011 and May 2012, respectively), on the dispensing of prescriptions suggestive of misuse.

Methods — The researchers conducted a time series analysis of publically-funded prescriptions for opioids, benzodiazepines and stimulants dispensed monthly from January 2007 to May 2013. In the primary analysis, a prescription was deemed potentially inappropriate if it was dispensed within 7 days of an earlier prescription for at least 30 tablets of a drug in the same class and originated from a different physician and different pharmacy.

Results — The prevalence of potentially inappropriate opioid prescriptions decreased by 13.2% after enactment of the new legislation (from 1.59% in October 2011 to 1.38% in April 2012; p=0.01). No further significant change in trend was observed after the introduction of the narcotic monitoring system (NMS) (p=0.78). By May 2013, the prevalence had dropped to 0.95%. Inappropriate benzodiazepine prescribing was significantly influenced by both the legislation (p<0.001) and the NMS (p=0.05), which together reduced potentially inappropriate prescribing by 57.5% between October 2011 and the end of the study period (from 0.40% to 0.17%). The prevalence of potentially inappropriate prescribing of stimulants was significantly influenced by the introduction of the NMS, falling from 0.68% in April 2012 to 0.27% in May 2013, following introduction of the NMS (p=0.02).

Interpretation — For a select group of drugs prone to misuse and diversion, legislation and implementation of a prescription monitoring program dramatically reduced the prevalence of prescriptions highly suggestive of misuse.