Implications of thrombocytopenia and platelet course on pediatric intensive care unit outcomes

Introduction: Thrombocytopenia has been shown to be an independent predictor of mortality and prolonged hospital length of stay in critically ill adults. Studies are lacking in the pediatric intensive care unit population. We evaluated the relationship between platelet counts at admission, platelet course, and outcomes. Hypotheses: 1) Thrombocytopenia at the time of admission to the pediatric intensive care unit is a risk factor for increased mortality and prolonged length of stay. 2) Thrombocytopenia at any point during pediatric intensive care unit stay is associated with increased mortality and length of stay. 3) Falling platelet counts during a pediatric intensive care unit course are associated with greater mortality and longer length of stay. Method: Prospective observational study. Study Population: All patients admitted to a multidisciplinary tertiary care pediatric intensive care unit in a University Hospital over the course of a year. Analysis of Data: Data were analyzed using logistic and linear regression. Results: Thrombocytopenia (platelet count <150 x 10(9)/L) was present in 17.3% of pediatric intensive care unit patients on admission. Mortality was higher in thrombocytopenic patients (17.6% vs. 2.47%, p < 0.001). The median length of stay in the thrombocytopenia and nonthrombocytopenia groups was 4 days vs. 1.6 days, respectively (p < 0.001). The pediatric intensive care unit patients (25.3%) were thrombocytopenic at some point in their stay. They had higher mortality (17.1% vs. 0.9%, odds ratio [OR] 23.8, 95% confidence interval [CI] 5.2-108.6, p < 0.0005) and longer length of stay (median 6.6 days vs. 1.5 days, p < 0.0005) compared with those who were never thrombocytopenic. For every 10% fall in platelet count from the time of admission, the OR for mortality was 1.4 (95% CI 1.1-1.8) and the length of stay was longer (p < 0.0005). Patients with normal platelet counts at admission who later developed thrombocytopenia had increased mortality (OR 18.6, 95% CI 3.2-107.3) and longer length of stay (p < 0.0005) compared with those who did not develop thrombocytopenia. Conclusion: Thrombocytopenia and falling platelet counts are associated with increased risk of mortality and length of stay in the pediatric intensive care unit. (Pediatr Crit Care Med 2008; 9: 502-505)