Background: Pharmacotherapeutical guidelines, called formularies, have been developed to facilitate effective, efficient and cost-conscious prescribing. Monitoring adherence to such guidelines may be a reasonable way of assessing prescribing practices.
Objective: The aim of this study was to assess how strictly the GPs participating in our department's registration network adhere to the guidelines of the regional formulary, and which indications and drugs the GPs used.
Methods: This is a descriptive study, concerning 1000 consecutive prescriptions from each of the 17 participating GPs. The third edition of the Groningen formulary (GFIII), published in 1995, was used. If the drug prescribed was advised in the formulary, we considered it to be global adherence. If the indication was mentioned in the formulary, and the drug prescribed was advised for that indication in the formulary, it was considered to be specific adherence. Both the medications prescribed and the health problems registered by the GPs, but not mentioned in the GFIII, were analysed.
Results: The 17 000 prescriptions chosen for analysis formed approximately 25% of all prescriptions written by the GPs in 1 year. The indications for only 24 prescriptions (0. 14%) were missing. Among the 17 GPs, the number of different drugs prescribed varied between 167 and 219 per 1000 prescriptions. The global adherence varied from 76 to 89% among the GPs, and the specific adherence varied from 55 to 71%. Of the 17 000 prescriptions, 11 457 (67%) concerned indications mentioned in the GFIII. Prescriptions for indications not mentioned in the GFIII contained 4353 (78.5%) drugs advised in the formulary. Of the 251 medications mentioned in the GFIII, only 15 (6%) were not prescribed.
Discussion: The GPs in our study were neither representative, nor were they chosen at random. Their patient population was comparable in age, sex and insurance status. These findings are an example of what level of adherence is obtainable. The formulary covered approximately two-thirds of the indications registered by GPs, and did not contain many unnecessary medications (6%).