Infections in primary care are often treated with non-steroidal anti-inflammatory drugs (NSAIDs). This study evaluates whether NSAID prescribing is associated with adverse outcomes for respiratory (RTIs) or urinary track (UTI) infections.

To determine whether there is an association between NSAID prescribing and the rate of adverse outcomes for infections for individual consulting in primary care.

Cohort study of electronic health records.

87 general practices in the UK Clinical Practice Research Datalink GOLD.

142 925 patients consulting with RTI or UTI.

Repeat consultations, hospitalisation or death within 30 days of the initial consultation for RTI or UTI. Poisson models estimated the associations between NSAID exposure and outcome. Rate ratios were adjusted for gender, age, ethnicity, deprivation, antibiotic use, seasonal influenza vaccination status, comorbidities and general practice. Since prescribing variations by practice are not explained by case mix—hence, less impacted by confounding by indication—both individual-level and practice-level analyses are included.

There was an increase in hospital admission/death for acute NSAID prescriptions (RR 2.73, 95% CI 2.10 to 3.56) and repeated NSAID prescriptions (6.47, 4.46–9.39) in RTI patients, and for acute NSAID prescriptions for UTI (RR 3.03; 1.92 to 4.76). Practice-level analysis, controlling for practice population characteristics, found that for each percentage point increase in NSAID prescription, the percentages of hospital admission/death within 30 days increased by 0.32 percentage points (95% CI 0.16 to 0.47).

In this non-randomised study, prescription of NSAIDs at consultations for RTI or UTIs in primary care is infrequent but may be associated with increased risk of hospital admission. This supports other observational and limited trial data that NSAID prescribing might be associated with worse outcomes following acute infection and should be prescribed with caution.