Objective Most pneumonia treatment guidelines recommend that prior outpatient antibiotic treatment should be considered when planning inpatient antibiotic regimen. Our purpose was to study in patients admitted for community-acquired pneumonia the mode of continuing antibiotic treatment at the outpatient to inpatient transition and the subsequent clinical course.

Design Retrospective cohort study.

Setting Dutch PHARMO Record Linkage System.

Participants 7323 patients aged >18 years and hospitalised with pneumonia in the Netherlands between 2004 and 2010.

Main study parameter We identified all prescribed antibiotics prior to, during and after hospitalisation. In case of prior outpatient treatment, the continuation of antibiotic treatment on admission was categorised as: no atypical coverage > no atypical coverage; atypical coverage > atypical coverage; no atypical coverage > atypical coverage; and atypical coverage > no atypical coverage.

Main outcome measures Length of hospital stay, in-hospital mortality and readmission within 30 days.

Results Twenty-two per cent of the patients had received prior outpatient treatment, of which 408 (25%) patients were switched on admission to antibiotics with atypical coverage. There were no differences in length of hospital stay, in-hospital mortality or readmission rate between the four categories of patients with prior outpatient treatment. The adjusted HR for adding atypical coverage versus no atypical coverage was 0.91 (95% CI 0.55 to 1.51) for time to discharge. For in-hospital mortality and readmission within 30 days, the adjusted ORs were 1.09 (95% CI 0.85 to 1.34) and 0.59 (95% CI 0.30 to 1.18), respectively.

Conclusions This study found no association between mode of continuing antibiotic treatment at the outpatient to inpatient transition and relevant clinical outcomes. In particular, adding atypical coverage in patients without prior atypical coverage did not influence the outcome.