Epidemiology, risk factors, and clinical outcome of community-acquired pneumonia in severely immunosuppressed patients: a comprehensive analysis from the multinational prospective <i>CAPNETZ Cohort</i>

Purpose Despite growing evidence that immunosuppression (IS) influences etiology and prognosis of community-acquired pneumonia (CAP) there remains a lack of data from representative multicenter studies. Methods The multinational prospective CAPNETZ-study includes patients with CAP and HIV since 2017 and with other causes of IS since 2020. We present the first comprehensive analysis of patients with CAP and IS (HIV with low CD4-cells, systemic steroids, immunosuppressive drugs, antineoplastic treatment, neutropenia, primary immunodeficiency, transplantation, hematologic neoplasia) included within CAPNETZ until December 2023. IS cases were matched 1:1 with non-IS patients. The primary endpoint was 30-day mortality and/or organ replacement therapy. Additionally, CAP caused by non-core respiratory pathogens (NCRP) according to an international consensus were evaluated. Univariate and multivariate risk factor analyses and evaluation of predictive scores by ROC-analysis were performed. Results We included 232 patients with IS, most commonly after antineoplastic therapy (37.5%), systemic steroids (36.2%) and immunosuppressive drugs (35.8%). 10.3% reached the primary endpoint. Overall, IS was not associated with prognosis compared to matched non-IS patients, but patients with immunosuppressive drugs had a significantly lower risk. The qSOFA, CRB-65 and CURB-65 scores showed limited prediction (AUC 0.57–0.64) and insufficient sensitivity for the primary endpoint. CAP caused by NCRP occurred in 16.4% in IS and was associated with transplantation, previous anti-infective treatment and ICU admission, but SARS-CoV-2, H. influenzae and S. pneumoniae were the most common pathogens in both groups. Conclusion This study demonstrates the relevance and heterogeneity of CAP in IS and highlights the need for individualized risk stratification and treatment.