Frequency, natural course, and outcome of neonatal neutropenia

Objective. We studied the frequency, onset, duration, and prognosis of neut ropenia in a neonatal hospital population to define subgroups of neonates w ho might benefit from cytokine therapy. Study Design. The study comprised of 2 parts: in a first retrospective stud y (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 o n septic neonates with and without neutropenia, and in study II, on neutrop enic neonates with and without primary infection. In the prospective part o f study II, granulocyte colony-stimulating factor (G-CSF) plasma concentrat ions were analyzed in neutropenic neonates (n = 32). Results. Thirty-eight percent of septic neonates were neutropenic. Neutrope nia 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 in cidence of neutropenia was 8.1%. Seventy-two percent of these neutropenic e pisodes occurred in patients without infection at the time of diagnosis of neutropenia. In the latter patients, the risk of infection secondary to neu tropenia was 9%, affecting only premature neonates. Neutropenic episodes wi thout infection were of longer duration and were accompanied by lower G-CSF plasma concentrations than were episodes associated with infection. The pe rcentage of neutropenic episodes primarily associated with infection was hi gher in VLBW neonates than in term neonates. Likewise, the risk of infectio n secondary to neutropenia (27%) and the mortality attributable to infectio n and neutropenia (28%) were significantly higher than in term newborns. Conclusion. Considering the priming time for induction of neutrophilia, G-C SF therapy in neonates presenting with severe bacterial infection and neutr openia may be too late. In contrast, neutropenic very low birth weight neon ates without primary infection might benefit from prophylactic G-CSF treatm ent.