Exploring patient- and doctor-related variables associated with antibiotic prescribing for respiratory infections in primary care.

Objective: To assess patient- and doctor-related variables leading physicians to prescribe antibiotics or parenteral antibiotics for acute respiratory infections (ARIs) and to describe the variability as well as the appropriateness of antibiotic use and its predictive factors in general practice.

Methods: We conducted a cross-sectional study among patients aged 15-85 years with a diagnosis of ARIs, using information from 469 GPs from the Health Search Database. Diagnoses were linked with antibiotic prescriptions and other patients and doctor-related variables. Available scientific evidence was used to establish the appropriateness of first-choice antibiotic treatment. Frequency analyses and logistic regressions were used to identify variables associated with antibiotic use and appropriateness.

Results: On 67,761 cases of ARIs, antibiotics were prescribed in 63.2%, varying from 80.9% for acute bronchitis to 43.9% for croup, influenza and common cold. Significant associations with antibiotic use were found for geographic location and number of patients under care. The use of diagnostic tests significantly lowered the risk. Geographic location and living in an urban area were associated with parenteral antibiotic use. Amoxicillin (16.7%) and amoxicillin-clavulanate (17.9%) were the most common antibiotics prescribed. Appropriateness was reported in 39.0% of cases, with geographic location, physician's gender and diagnostic tests being the factors more predictive of appropriate antibiotic use.

Conclusions: There is still excessive antibiotic use for ARIs. Its overuse is influenced by the physicians' characteristics and by the environment in which they practice, whilst diagnostic tests might reduce inappropriateness. Therefore, effective strategies for changing diagnostic and therapeutic behaviour are needed.