Increase in antibiotic prescriptions in out-of-hours primary care in contrast to in-hours primary care prescriptions: service evaluation in a population of 600 000 patients.

Objectives: The objective of this study was to describe the frequency and nature of antibiotic prescriptions issued by a primary care out-of-hours (OOH) service and compare time trends in prescriptions between OOH and in-hours primary care.
Methods: We performed a retrospective audit of 496 931 patient contacts with the Oxfordshire OOH primary care service. Comparison of time trends in antibiotic prescriptions from OOH primary care and in-hours primary care for the same population was made using multiple linear regression models fitted to the monthly data for OOH prescriptions, OOH contacts and in-hours prescriptions between September 2010 and August 2014.
Results: Compared with the overall population contacting the OOH service, younger age, female sex and patients who were less deprived were independently correlated with an increased chance of a contact resulting in prescription of antibiotics. The majority of antibiotics were prescribed to patients contacting the service at weekends. Despite a reduction in patient contacts with the OOH service [an estimated decrease of 486.5 monthly contacts each year (95% CI -676.3 to -296.8), 5.0% of the average monthly contacts], antibiotic prescriptions from this service rose during the study period [increase of 37.1 monthly prescriptions each year (95% CI 10.6-63.7), 2.5% of the average monthly prescriptions]. A matching increase was not seen for in-hours antibiotic prescriptions; the difference between the year trends was significant (Z test, P = 0.002).
Conclusions: We have demonstrated trends in prescribing that could represent a partial displacement of antibiotic prescribing from in-hours to OOH primary care. The possibility that the trends we describe are evident nationally should be explored.
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