Incidence and predictors of idiopathic pneumonia syndrome in hematopoietic stem cell transplant patients

Idiopathic pneumonia syndrome (IPS) is a rare but deadly complication of hematopoietic stem cell transplantation (HSCT). This study characterized the incidence and risk factors for IPS after HSCT in Taiwan. Data from January 2009 to February 2019 was collected from the Taiwan Society of BMT national registry. Forty-three (1.1%) of 3924 HSCT patients who developed IPS were identified. Incidence of IPS was lower in patients who received autologous HSCT than patients who received allogeneic HSCT (0.68% vs 1.44%, P = 0.022). Multivariate analysis showed that use of TBI and intravenous busulfan in the conditioning regimen were each independent predictor of IPS after HSCT. In addition, development of IPS was significantly associated with increased risk of death in the first 120 days post-HSCT (HR, 2.09; 95% CI, 1.08 to 4.05, P = 0.029) and 2 years post-HSCT (HR, 1.65; 95% CI, 1.07 to 2.542, P = 0.023), but not beyond 2 years post-HSCT. However, survival outcomes did not differ significantly between patients with IPS who received autologous versus allogeneic HSCT (P = 0.52). In conclusion, despite the relatively low incidence of post-HSCT IPS in Taiwan, mortality remains high. The results of this study will help to identify high-risk patients for early intervention and guide future therapeutic research.