Antimicrobial use in defined populations of infants and young children

Background: Antimicrobial overprescribing contributes to bacterial resistance, but data on use in infants and young children are limited. Objectives: To assess antimicrobial use in a defined population of infants and young children and to determine diagnosis-specific prescribing rates for common infections. Design and Setting: Retrospective cohort study of children served by 44 practices affiliated with 2 managed care organizations. Patients: Children aged 3 months to 72 months enrolled in either health plan between September 1, 1994, and August 31, 1996. Analysis: Rates of antimicrobial use were calculated as the number of pharmacy dispensings divided by the number of person-years of observation contributed to the cohort in 2 age groups (3 to <36 months and 36 to <72 months). Other outcomes included the distribution of diagnoses associated with antimicrobial dispensing and population-based rates of diagnosis of common acute respiratory tract illnesses. Results: A total of 46 477 children contributed 59 710 person-years of observation across the 2 health plans. Rates of antimicrobial dispensing for children aged 3 to 36 months were 3.2 and 2.1 dispensings per person-year in the 2 populations. A substantial fraction of younger children (35% in population A and 23% in population B) received 4 or more antimicrobial prescriptions in a single year. For children aged 36 to 72 months, the dispensing rates for the 2 populations were 2.0 and 1.5 antimicrobials per person-year. We found significant differences in rates between the populations studied and a decrease in use at all sites from 1995 to 1996. The diagnosis of otitis media accounted for 56% of antimicrobial drugs dispensed to children aged 3 to 36 months and 40% of those dispensed to children aged 36 to 72 months. Antimicrobial prescribing for colds and upper respiratory tract infections, bronchitis, and sinusitis was less frequent than previously reported but accounted for 10% to 14% of antimicrobial drugs dispensed. Conclusions: In these populations, otitis media accounted for the largest number of antimicrobial agents dispensed to children younger than 6 years. Clearly inappropriate indications such as cold, upper respiratory tract infection, and bronchitis accounted for smaller fractions of antimicrobial use but may be most amenable to change. However, interventions that encourage use of strict criteria for diagnosis and treatment of otitis media will likely have the greatest impact on overall antimicrobial exposure. Monitoring defined populations longitudinally will allow assessment of the effectiveness of such national and local initiatives.