Do general practitioners' consultation rates influence their prescribing patterns of antibiotics for acute respiratory tract infections?

Objectives: To examine general practitioners' (GPs') antibiotic prescribing patterns for acute respiratory tract infections (ARTIs) as compared with national guidelines. We also wanted to explore possible predictors of antibiotic prescription patterns. Methods: Observational study based on prescription data from 440 Norwegian GPs in December 2004 through to November 2005. Outcome measures were the type and frequency of antibiotic prescriptions for various ARTI diagnoses, with patients' and GPs' characteristics as explanatory variables. Results: In the study period, the 440 GPs treated a total of 142900 ARTI episodes. In 33.5% [95% confidence interval (CI): 31.9%-35.1%] of these episodes an antibiotic was issued, of which penicillin V (pcV) accounted for 41.2% (95% CI: 37.4%-44.9%). GPs with a high number of total annual encounters had higher antibiotic prescription rates for ARTIs and used more non-pcV antibiotics compared with GPs with fewer annual patient encounters. GPs in the highest quintile with respect to the total annual encounter rate had 1.6 times the odds of prescribing antibiotics compared with GPs in the lowest quintile. Correspondingly, the odds of choosing a non-pcV antibiotic were 2.8 times higher in the top quintile of GPs compared with GPs in the bottom quintile with respect to antibiotic prescription rates. Conclusions: ARTIs are frequently treated with antibiotics and often with broader spectrum agents than pcV, which is the recommended first-line antibiotic in the Norwegian guidelines. GPs with a high practice activity are, in general, more liberal with respect to the prescription of antibiotics for ARTIs, and the higher the antibiotic prescription rate, the larger the share of non-pcV agents.