The value of leukopenia during the first hour of admission as a prognostic marker in meningococcal infection

Abstract

Objective: To stablish the temporal course of the white cell blood count (WBC) in patients with meningococcal infection during the first 24 hours after hospital admission and to evaluate the role of leukopenia in the first hour as a mortality risk factor.

Design: Non-blind, non-analytical, prospective cohort study in the paedriatric ICU of a general hospital. All patients with meningococcal infection presenting between 1999 and 2002 were included. The WBC count was measured at the time of admission, and at 1, 6, 12 and 24 hours after admission. Leukopenia was defined as a WBC < 5,000/mm3.

Results: 75 children, aged between 3 months to 12 years, were recruited. 56% of cases were confirmed by meningococcal culture. The mortality was 6.7%, all presenting with purpura fulminans. At admission 15% (11/75) had leukopenia, and 17% (13/75) after 1 hour. 22% of non-leukopenic patients had a decrease in the WBC count, but did not reach the leukopenic level. At the time of admission 69% of leukopenic children were hypotensive compared with 17% of non-leukopenic children (RR = 3.9 p < 0.001). The 5 children who died all showed leukopenia (5/13 38%) at 1 hour, while none of children with a normal WBC died. (RR = 2.07, p < 0.001, sensitivity 100% and negative predictive value 100%). The WBC nadir occurred after the first hour of admission, median 2,100/mm3 range 1,200-3,100/mm3.

Conclusions: Leukopenia in meningococcal infections during the first hour of admission in the ITU doubles the risk of dying.