Platelet counts and outcome in the pediatric intensive care unit

OBJECTIVES: Thrombocytopenia is commonly observed in critically ill patients. This study was undertaken to evaluate the variation in platelet counts and the risk factors associated with thrombocytopenia and mortality in pediatric intensive care patients. In addition, prognostic value of platelet counts for outcome in pediatric intensive care unit was studied. STUDY DESIGN: Prospective, observational cohort analysis. SETTING: 8- bedded pediatric intensive care unit of a tertiary care teaching hospital. PATIENTS: All consecutively admitted patients (n=138) staying in the pediatric intensive care unit (PICU) for at least 48h over a 7 months period were studied. MEASUREMENTS AND MAIN RESULTS: Thrombocytopenia was defined as platelet counts <150.0/nL. Median 1(st) day Pediatric Risk of Mortality Score (PRISM) was 5 (range 0-30) and median ICU stay was 4 days (range 2-98 days). Twenty five percent patients had at least one episode of thrombocytopenia during the stay. Twenty percent of these patients had thrombocytopenia on admission and rest (80%) developed it during the PICU stay. Seventy one percent (19) of the patients developed thrombocytopenia by fourth day of admission. Patients with PICU acquired thrombocytopenia had statistically significant lower baseline, nadir and 4th day platelet counts and a significantly higher drop in platelet counts (56% vs. 6% P<0.001) as compared to non thrombocytopenic patients. PRISM score, long PICU stay, sepsis, coagulopathy, and creatinine levels were significantly associated with occurrence of thrombocytopenia. Patients with thrombocytopenia had higher probability of bleeding (34% vs. 15%, P=0.01). Higher platelet counts on admission were associated with significantly reduced risk of thrombocytopenia (P=0.00) Baseline, nadir and day-4 platelet counts, presence of thrombocytopenia on admission, sepsis, coagulopathy and a higher mean PRISM score on univariate analysis were significantly associated with mortality. Leucopenia or leucocytosis, thrombocytopenia and coagulopathy were found to significantly affect outcome. Drop in platelet counts was found to have slightly higher discriminative value for mortality prediction than PRISM on the ROC curve. The survivors had higher platelet counts throughout the PICU stay and after an initial fall in platelet counts in the PICU showed a significantly higher rise in the platelet counts in the following days than the non-survivors. CONCLUSIONS: Thrombocytopenia is common in PICU. Patients requiring cardiopulmonary resuscitation or with circulatory shock, coagulopathy, sepsis and with more severe disease have higher risk of developing thrombocytopenia. Thrombocytopenic patients have a higher risk of bleeding. Drop in platelet counts >27% and thrombocytopenia were independently related to mortality. Serial measurements of platelet counts are better predictors of pediatric intensive care outcome than one-time values. Any drop in platelet counts even without thrombocytopenia needs an urgent and extensive evaluation.