Role of diagnostic labeling in antibiotic prescription.

Objective: To evaluate the association between diagnostic labeling of respiratory tract infections (RTIs) and antibiotic prescription rates in family practice.

Design: Descriptive analysis of outpatient chart review supplemented by interviews with physicians. Charts of patients attending 73 general practitioners were reviewed between October 1997 and February 1998. Two days of practice were evaluated per physician.

Setting: Urban family practices in greater St John's, Nfld.

Participants: Of 96 family physicians contacted, 73 (76%) agreed to participate.

Main Outcome Measures: Rates of diagnoses and antibiotic prescriptions for acute infections. Physicians were divided into "low prescribers" and "high prescribers" based on overall rates of prescription to patients with infections. Low prescribers were compared with high prescribers with respect to physician characteristics, patient characteristics, and diagnoses assigned.

Results: Of all patients seen, 22% were seen for acute infections; RTIs accounted for 76% of diagnoses. Low prescribers and high prescribers were of similar ages and saw similar numbers of patients of similar ages with very similar presenting complaints. Both groups diagnosed urinary tract and skin and soft-tissue infections at similar rates, but differed markedly in their rates of diagnoses of RTIs. High prescribers diagnosed bacterial RTIs in 65.4% (147/225) of their patients; low prescribers diagnosed bacterial RTIs in 31.0% (66/213 (P < .001).

Conclusion: Family doctors frequently prescribe antibiotics. The difference in rates of prescription between high prescribers and low prescribers is largely explained by assignment of diagnoses of RTIs.