BACKGROUND: Post-discharge complications resulting in readmission or death after hospitalization for community-acquired-pneumonia (CAP) pose a serious healthcare burden. However, their extent and associated risk factors remain underexplored.

OBJECTIVE: To assess short-term readmission and mortality after inpatient CAP-treatment and identify underlying risk factors.

METHODS: We conducted a retrospective population-based cohort-study using German health insurance data from 2015-2018. Patients discharged alive from CAP-hospitalization were included. CAP was identified by ICD-10-GM-codes, and underlying conditions using ICD-10-, ATC- and OPC-coding. The composite primary endpoint was defined as combination of secondary endpoints: (1) readmission due to repeated CAP, (2) CAP-unrelated readmission and/or (3) all-cause death, each within 30 days post-discharge. A Cox-model adjusted for sex, age, long-term care, vaccination status, community type and comorbidities including immunosuppression was applied.

RESULTS: Among 21,419 discharged CAP-patients, the composite endpoint occurred in 6124 (28.6 %) including 1118 (5.2 %) readmissions due to CAP, 3571 (16.7 %) CAP-unrelated readmissions and a 30-day mortality of 9.8 % (2,101). Age (up to HR 2.09[1.59-2.76]) and long-term care (up to HR 1.99[1.83-2.16]) were risk factors for the primary endpoint and significantly increased 30-day mortality (up to HR 17.18[5.50-53.67] and HR 6.71[5.63-8.01]). Male sex (HR 1.07-1.32) and immunosuppression (HR 1.36-1.50) were associated with all endpoints. Patients requiring long-term care (up to HR 2.37[1.95-2.87]) were additionally prone to readmissions due to repeated CAP while cardiovascular (HR 1.22[1.14-1.31]) and malignant diseases (HR 1.25[1.14-1.37]) were associated with CAP-unrelated readmissions. Flu vaccination reduced post-discharge mortality (HR 0.89[0.81-0.97]).

CONCLUSION: Risk-based assessments for complications after CAP-hospitalization are crucial to implement targeted preventive interventions.