PREDICTORS OF HEMOLYTIC-UREMIC SYNDROME IN CHILDREN DURING A LARGE OUTBREAK OF ESCHERICHIA-COLI O157 H7 INFECTIONS/

Objective. To evaluate risk factors for progression of Escherichia col i O157:H7 infection to the hemolytic uremic syndrome (HUS). Study Desi gn. We conducted a retrospective cohort study among 278 Washington Sta te children <16 years old who developed symptomatic culture-confirmed E coli O157:H7 infection during a large 1993 outbreak. The purpose of the study was to determine the relative risk (RR) of developing HUS ac cording to demographic characteristics, symptoms, laboratory test resu lts, and medication use in the first 3 days of illness. Results. Thirt y-seven (14%) children developed HUS. In univariate analysis, no assoc iations were observed between HUS risk and any demographic characteris tic, the presence of bloody diarrhea or of fever, or medication use. I n multivariate analysis, HUS risk was associated with, in the first 3 days of illness, use of antimotility agents (odds ratio [OR] = 2.9; 95 % confidence interval [CI] 1.2-7.5) and among children <5.5 years old, vomiting (OR = 4.2; 95% CI 1.4-12.7). Among the 128 children tested, those whose white blood cell (WBC) count was 13 000/mu L in the first 3 days of illness had a 7-fold increased risk of developing HUS (RR 7. 2; 95% CI 2.8-18.5). Thirteen (38%) of the 34 patients with a WBC coun t 13 000/mu L developed HUS, but only 5 (5%) of the 94 children whose initial WBC count was <13 000/mu L progressed to HUS. Among children w ho did not develop HUS, use of antimotility agents in the first 3 days of illness was associated with longer duration of bloody diarrhea. Co nclusions. prospective studies are needed to further evaluate measures to prevent the progression of E coli O157:H7 infection to HUS and to assess further clinical and laboratory risk factors. These data argue against the use of antimotility agents in acute childhood diarrhea. Ou r finding that no intervention decreased HUS risk underscores the impo rtance of preventing E coli O157:H7 infections.