Drop in platelet counts in extremely preterm neonates and its association with clinical outcomes

BACKGROUND: Thrombocytopenia is a common finding among preterm neonates and has been associated with mortality and morbidities. In recent studies in adults, the drop in platelet numbers has been shown to be a predictor of clinical outcomes. Although drop in the platelet counts with or without thrombocytopenia has also been observed in neonates, its association with mortality and morbidity has not been investigated in the preterm population. OBJECTIVE: To study the prevalence of a 30% drop in platelet counts in preterm neonates and its association with clinical outcomes. METHODS: Retrospective chart review was done on neonates born at gestational age ≤28 weeks and survived for 7 days. As with the adult studies, a 30% drop in platelet numbers were identified at 7 days and 28 days of age and their association with mortality, morbidities, and length of stay (LOS) was investigated. RESULTS: Two hundred eighty-six patients included in the study had a mean gestational age of 26.3 weeks (range, 23 to 28 wk) and birth weight of 899±215 grams. A 30% drop in platelet counts occurred in 68.1% neonates. It was significantly associated with mortality (P<0.001), morbidities at both 7 and 28 days [intraventricular bleed (P<0.01)], retinopathy of prematurity (P<0.01), necrotizing enterocolitis (P<0.05) and gram-positive infections (P<0.05), and LOS (P<0.01). Only those neonates who had a 30% drop in the platelet numbers developed gram negative and fungal infections. These associations of clinical morbidities and mortality with a 30% drop in platelet counts were independent of thrombocytopenia. CONCLUSIONS: A 30% drop in platelet counts is associated with increased mortality, morbidities, and LOS in preterm neonates, independent of thrombocytopenia. As the drop occurs before the onset of clinical morbidity, one potential application is its use to predict the onset of morbidities including necrotizing enterocolitis, intraventricular hemorrhage, and retinopathy of prematurity, and a prolonged LOS and mortality.