Patient and prescriber determinants for the choice between amoxicillin and broader-spectrum antibiotics: a nationwide prescription-level analysis.

Bacterial resistance to antibiotics, driven by antibiotic consumption, imposes a major threat to the effective treatment of bacterial infections. In addition to reducing the amount of antibiotics prescribed, avoiding broad-spectrum antibiotics could extend the lifetime of the current arsenal of antibiotic substances. Therefore, we documented prescriber and patient characteristics associated with the choice between amoxicillin and broader-spectrum alternatives (co-amoxiclav or moxifloxacin) in recent years in Belgium. Complete reimbursement claims data (2002-09) for antibiotic prescriptions in outpatient care, including patient and prescriber characteristics, were collected for both young children (1-5 years) and the adult population (30-60 years). A backwards selection procedure within generalized estimating equations retained the most relevant determinants. The age, gender and social category of the patient were found to be predictive of the extent to which amoxicillin was prescribed instead of the broader-spectrum alternatives, with female patients generally taking a higher proportion of amoxicillin than male patients. The age category of 40-44-year-old prescribers exhibited a preference for broad-spectrum antibiotics compared with both younger and older age groups. Significant interactions between the region and the prescriber's qualification (general practitioner or paediatrician) on the choice of antibiotic for children were found. Patient (age, gender and social category) and prescriber characteristics (age, gender, region and qualification) had an influence on whether amoxicillin or the alternative broad-spectrum antibiotics were prescribed. These findings should help policy makers to better target future campaigns to promote prudent prescribing of antibiotics.