Incidence, clinical features, and risk factors of idiopathic pneumonia syndrome following hematopoietic stem cell transplantation in children

Background: Idiopathic pneumonia syndrome (IPS) is a severe complication that can occur after hematopoietic stem cell transplantation (HSCT) and is often associated with a fatal outcome despite intensive supportive care. Procedure: To assess the incidence and risk factors of IPS, we reviewed 251 consecutive patients (median age, 7.0 years) who received HSCT at the Department of Pediatrics, Nagoya University Hospital, between January 1990 and July 2009. Results: Twenty of 251 (cumulative incidence of IPS at 2 years after HSCT, 8.0%; 95% confidence interval (CI), 5.1-12.4%) patients developed IPS. The median duration from HSCT to diagnosis of IPS was 67 days (range, 12-486 days). Patients with IPS had significantly higher 5-year transplant-related mortality compared to patients without IPS (52% (95% CI, 19-77%) vs. 13% (95% CI, 5-25%), P<0.001), and the probability of 5-year overall survival was significantly worse for patients with IPS (42% (95% CI, 25-64%) vs. 68% (95% CI, 59-76%), P=0.01). By multivariate analysis, high risk in underlying disease (HR, 2.5; 95% CI, 1.0-6.7; P=0.05) and a busulfan-containing regimen (HR, 3.5; 95% CI, 1.3-9.9; P<0.01) were identified as the independent risk factors for developing IPS. Conclusion: The prophylactic strategies for IPS in patients with these risk factors were warranted.