Aims: To investigate the extent of dose-related off-label antibiotic paediatric prescribing in primary care and to identify any potential clinical effects, particularly of lower than recommended dose prescribing.
Methods: Assessment of antibiotic prescribing in 168 396 children aged 0-16 years for the year 1999-2000 from data retrieved from 158 general practices using the national Scottish primary care computer system GPASS. The setting was general practices in Scotland.
Results: During the study period at least one course of antibiotics was prescribed to 23 911 children (14.2%). A total of 4582 (19.2%) children were prescribed an antibiotic dose of less than that recommended in the Summary of Product Characteristics (SPC). The number of children prescribed an antibiotic at less than recommended dose increased with age from 1154 (11.8%) aged 0-4 years to 1827 (30.0%) in the 12-16 years age group. For each antibiotic, prescribing lower than recommended dose occurred most frequently at those ages at which a dose increase was recommended in the SPC. Antibiotic prescribing at less than the recommended dose was not associated with an increased return rate for further antibiotic prescriptions during the following month, but in 5-11-year-olds was associated with a significant 48% increase in the total number of antibiotic courses prescribed during the study year [mean = 2.09 [95% confidence interval (CI) 1.79, 2.39]vs. 1.41 [95% CI 1.35, 1.47]]. Antibiotic prescribing at doses higher than recommended occurred less frequently (1.6%) and decreased steadily with age.
Conclusions: Off-label prescribing of antibiotics at less than the recommended dose in children is common in primary care and occurs primarily as the result of a failure to increase antibiotic dosage with age in line with SPC recommendations. Adoption of a uniform approach to SPC age banding for antibiotic dose increments would reduce the frequency of dose-related off-label antibiotic prescribing in children and help minimize the potential for the development of antibiotic resistance.