Objectives: To determine factors associated with hospitalisation after community-acquired pneumonia (CAP) among older adults in England, and to investigate how these factors have contributed to increasing hospitalisations over time.
Design: Cohort study
Setting: Primary and secondary care in England
Population: 39,211 individuals from the Clinical Practice Research Datalink who were eligible for linkage to Hospital Episode Statistics and mortality data, were aged ≥65 and had at least one CAP episode between April 1998 and March 2011.
Main outcome measures: The association between hospitalisation within 28 days of CAP diagnosis (a “post-CAP” hospitalisation) and a wide range of co-morbidities, frailty factors, medications and vaccinations. We examined the role of these factors in post-CAP hospitalisation trends. We also looked at trends in post-CAP mortality and length of hospitalisation over the study period.
Results: Fourteen co-morbidities, five frailty factors, and four medications/vaccinations were associated with hospitalisation (of 18, 12 and 7 considered respectively). Factors such as chronic lung disease, severe renal disease and diabetes were associated with increased likelihood of hospitalisation, whereas factors such as recent influenza vaccination and a recent antibiotic prescription decreased the odds of hospitalisation. Despite adjusting for these and other factors, the average predicted probability of hospitalisation after CAP rose markedly from 57% (1998-2000) to 86% (2009-2010). Duration of hospitalisation and 28-day mortality decreased over the study period.
Conclusion: The risk factors we describe enable identification of patients at increased likelihood of post-CAP hospitalisation and thus in need of proactive case management. Our analyses also provide evidence that while co-morbidities and frailty factors contributed to increasing post-CAP hospitalisations in recent years, the trend appears to be largely driven by changes in service provision and patient behaviour.