Prognostic factors of early outcome in pediatric hemophagocytic lymphohistiocytosis: an analysis of 116 cases

Early mortality remains a major challenge for the treatment of hemophagocytic lymphohistiocytosis (HLH), which warrants the need for prompt risk stratification in the early phase of the disease. We retrospectively analyzed clinical features of a cohort of pediatric patients managed at a tertiary hospital in southern China from 2005 to 2015. A total of 116 patients (median age 27.5 months) with predominantly secondary HLH were included. In a multivariate Cox regression model, neutrophils <0.5 × 10⁹/L (risk ratio (RR) = 5.01; 95 % confidence interval (CI) 1.55–16.20; P = 0.007), total bilirubin over twofold upper limit of normal value (RR = 2.86; 95 % CI 0.83–9.88; P = 0.097), and albumin ≤20 g/L (RR = 5.79; 95 % CI 1.70–19.73; P = 0.005) at diagnosis were independent risk factors for 30-day mortality. The 30-day overall survival rate (OS) of patients with three risk factors was significantly lower than that of patients with zero to two risk factors (0 vs 90.7 %; P<0.001). Patients with three risk factors were 64-fold more likely to have early adverse outcome as compared to patients with zero to two risk factors (RR = 64.45; 95 % CI 18.35–226.33; P<0.001). Platelet count normalization in 2 weeks was an independent predictor for resolution after initial therapy with an odds ratio (OR) of 18.4 (95 % CI 2.7–122.9; P = 0.003). Our results indicate that severe neutropenia and liver function damage are prognostic factors for early death in HLH and platelet count normalization in 2 weeks is a critical predictor for resolution after initial therapy.