Frequency, natural course, and outcome of neonatal neutropenia

Objective. We studied the frequency, onset, duration, and prognosis of neutropenia in a neonatal hospital population to define subgroups of neonates who might benefit from cytokine therapy. Study Design. The study comprised of 2 parts: in a first retrospective study (I), clinical data of neonates with sepsis (n = 168) were analyzed; in a second retrospective and prospective study (II), clinical data of neonates with neutropenia (n = 131) were studied. In study I, the analysis focused on septic neonates with and without neutropenia, and in study II, on neutropenic neonates with and without primary infection. In the prospective part of study II, granulocyte colony-stimulating factor (G-CSF) plasma concentrations were analyzed in neutropenic neonates (n = 32). Results. Thirty-eight percent of septic neonates were neutropenic. Neutropenia lasted <24 hours in 75% of these patients. It was recorded before or on the day of the clinical onset of sepsis in 87% of patients. The overall incidence of neutropenia was 8.1%. Seventy-two percent of these neutropenic episodes occurred in patients without infection at the time of diagnosis of neutropenia. In the latter patients, the risk of infection secondary to neutropenia was 9%, affecting only premature neonates. Neutropenic episodes without infection were of longer duration and were accompanied by lower G-CSF plasma concentrations than were episodes associated with infection. The percentage of neutropenic episodes primarily associated with infection was higher in VLBW neonates than in term neonates. Likewise, the risk of infection secondary to neutropenia (27%) and the mortality attributable to infection and neutropenia (28%) were significantly higher than in term newborns. Conclusion. Considering the priming time for induction of neutrophilia, G-CSF therapy in neonates presenting with severe bacterial infection and neutropenia may be too late. In contrast, neutropenic very low birth weight neonates without primary infection might benefit from prophylactic G-CSF treatment.