Do prescribing formularies help GPs prescribe from a narrower range of drugs? A controlled trial of the introduction of prescribing formularies for NSAIDs.

BACKGROUND Previous studies have suggested that prescribing formularies may promote rational prescribing. The range of drugs prescribed may be one aspect of rational prescribing. AIM To determine whether the introduction of prescribing formularies helps general practitioners (GPs) to prescribe from a narrower range of non-steroidal anti-inflammatory drugs (NSAIDs). METHOD General practices in Lincolnshire were offered help in developing prescribing formularies. Ten practices decided to develop a formulary for NSAIDs. Level 3 PACT data were used to determine whether changes in prescribing had occurred with the introduction of the formulary. Matched controls were used to determine whether similar changes had occurred in other practices. RESULTS Between April and June 1992, and during the same period in 1993, practices that introduced a formulary for NSAIDs reduced the mean number of different drugs used (14.3 versus 13.1, P = 0.04) and increased the percentage of NSAID-defined daily doses coming from the three most commonly used drugs (70.1% versus 74.8%, P = 0.02). Similar changes were not seen in control practices. CONCLUSION Following the development of a formulary for NSAIDs, practices prescribed from a narrower range of drugs and focused a greater proportion of their prescribing on their three most commonly used drugs.