Risk Factors and Outcomes of Pneumocystis jirovecii Pneumonia after Allogeneic Hematopoietic Stem Cell Transplantation for Hematological Malignancy: A 10-Yr Cohort Study

Abstract

Pneumocystis jirovecii pneumonia (PJP) is a life-threatening opportunistic infection that occurs after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The risk factors and prognostic factors for PJP under current transplantation and monitoring practices are not well understood. In this retrospective cohort study, we aimed to characterize the clinical features, identify risk factors for its occurrence, and determine prognostic factors of PJP for survival. Between 2012 and 2022, 8596 patients underwent allo-HSCT at the Peking University Institute of Hematology. From this cohort, 88 patients with PJP were retrospectively identified, and after 16 patients were excluded because of incomplete data or loss to follow-up, 72 patients were included in the final analysis. We also conducted a nested case–control study to identify risk factors associated with PJP onset. For every patient diagnosed with PJP, three control subjects were randomly chosen and matched by transplant date within 90 d and follow-up duration within 180 d. Finally, 72 PJP patients and 216 controls without PJP were analyzed. In this study, the prevalence of PJP post allo-HSCT was 1.0% (88/8596). Patients who developed PJP had significantly lower 5-yr overall survival (OS) (58.7% versus 84.3%; P < .001) and 5-yr disease-free survival (57.3% versus 82.0%; P < .001) and higher 5-yr nonrelapse mortality (33.0% versus 8.5%; P < .001) than the controls did. The median time from transplantation to PJP diagnosis was 10 mo, with 29.2% of cases occurring more than 1 yr post-HSCT. Multivariate analysis revealed that an age greater than 45 yr at transplantation, peak corticosteroid dose, and lower CD4⁺ T cell count were independent risk factors for developing PJP. Among patients with PJP, the presence of chronic graft-versus-host disease, coexisting EBV infection, anemia (hemoglobin <100 g/L), and respiratory failure were independent predictors of poor OS. Our findings revealed that patients with PJP had a poor prognosis. These results suggest that the standard duration of prophylaxis may be insufficient for many patients, underscoring the need for individualized, risk-adapted strategies. Early identification of high-risk patients could guide prolonged prophylaxis and improve outcomes.