The Significance of Depression for Short-term Readmission and Mortality After a Pneumonia Admission

BACKGROUND: Depression is highly prevalent among hospitalized patients with pneumonia. At discharge, these patients transfer to a less care-intensive home-based setting. Nevertheless, little is known on the prognosis in the postdischarge period. OBJECTIVE: The objective of this study was to investigate the influence of depression on 30-day mortality and readmission in persons discharged after a pneumonia admission. DESIGN: This was a population-based cohort study using the Danish registries. SUBJECTS: All persons aged 50+ years with a pneumonia admission in 2000-2016 in Denmark. MEASURES: Mortality rate ratios for 30-day mortality and incidence rate ratios for 30-day readmission in pneumonia patients with versus without depression. RESULTS: We identified 379,265 pneumonia admissions, hereof 83,257 (22.0%) with depression. The overall adjusted mortality rate ratio was 1.29 (95% confidence interval: 1.25-1.33), and the overall adjusted incidence rate ratio was 1.07 (95% confidence interval: 1.05-1.08). The mortality risk was higher for all ages and throughout the 30-day period in persons with versus without depression. This risk was modified by sociodemographic and socioeconomic characteristics (excluding sex and education), admission-related factors, comorbidities, and use of benzodiazepines, opioids, or antipsychotics. The readmission risk was higher until age 90 and tended to be higher throughout the 30-day period. This risk was modified by age, cohabitation, residency, admission-related factors, comorbidities, and use of opioids or antipsychotics. For both outcomes, the relative effect of depression was highest among the youngest, among those with a short hospital stay and among those with few comorbidities. CONCLUSION: Depression is an independent risk factor for 30-day mortality and readmission in persons who transfer from hospital care to home-based care.