Severe Community-Acquired Pneumonia in Immunosuppressed Patients Admitted to the ICU.

Background: Immunocompromised patients with severe Community-Acquired Pneumonia (sCAP) poses higher risk for poor prognosis. This study details the clinical characteristics and factors linked to immunosuppression and mortality both acutely and long-term. Methods: This analysis of the MIMIC-IV database included ICU adult patients with CAP diagnosis categorized by the presence or absence of immunosuppression. Univariable and multivariable analyses determined factors related to immunosuppression and in-hospital, 6-and 12-month mortality post-admission. An adjusted survival analysis assessed the impact of immunosuppression on mortality. Results: A total of 4742 patients were included, with 1520/4742 (32 %) immunocompromised with a mean age (SD) of 64 (14.7) years, and 896/1520 (58.9 %) males. Solid malignancy was the most frequent immunosuppression cause (797/1520; 52.4 %). The most frequent comorbidities were chronic pulmonary disease (585/1520; 38.5 %) and congestive heart failure (411/1520; 27 %). Immunocompromise was associated with P. jirovecii (0.3 % vs. 1.1 %; p < 0.01) and Aspergillus (1.2 % vs 3.1 %; p 0.03) infection and increased hospital (IH) and solid malignancy (IH: OR 1.98 [95 % CI 1.55–2.52]; 6 M: OR 2.43 [95 % CI: 1.92–3.08]; 12 M: OR: 0.72 [95 % CI 0.47–1.11]; p = 0.14) was consistently associated with mortality at in-hospital and 6M follow-up. Conclusion: Immunocompromised patients with sCAP had higher acute and long-term mortality independent of the disease severity and were frequently infected with opportunistic microorganisms.