Do quality incentives change prescribing patterns in primary care? An observational study in Scotland

Background. The 2004 General Medical Services (GMS) contract introduced financial incentives for the management of chronic illnesses in 10 clinical areas. The effect of the scheme on prescribing is unknown. Objectives. To quantify the impact of the latest GMS contract, which incorporates additional payments for quality outcomes, on prescribing patterns in GP practices. Methods. This retrospective observational study of prescribing compared the defined daily doses (DDDs) for drugs mentioned or implied within the Quality and Outcomes Framework (QOF) of the latest GMS contract (QOF drugs) to the DDDs for all other drugs listed within the first 10 chapters on the British National Formulary (non-QOF drugs) for four financial years; two before and two after the introduction of the latest GMS contract. These measures were calculated for 92 GP practices of 100 in the Lothian region of Scotland, and the rate of change of prescribing was calculated from regression slopes within the log-scale interrupted time series analyses. Results. The prescribing of QOF drugs increased significantly faster than the non-QOF drugs both before and after the introduction of the latest GMS contract but the rate of increase for the QOF drugs slowed significantly after April 2005 unlike prescribing of non-QOF drugs. Conclusions. The prescribing of relevant drugs increased before the introduction of the 2004 GMS contract; the increase continued in the first 2 years of the new contract but at a significantly lower level.