Microalbuminuria three years after recovery from Escherichia coli O157 hemolytic uremic syndrome due to municipal water contamination

Background. Knowledge of the long-term renal prognosis of diarrhea associated hemolytic uremic syndrome (HUS) is important for patient counseling and follow-up. However, estimates of long-term risk are highly variable, with previous studies not using a healthy control group. Methods. A municipal water system in the small rural town of Walkerton, Ontario, became contaminated with Escherichia coli O157:H7 in 2000. A cohort of 19 children who recovered from HUS was randomly age- and sex-matched to 38 children with no symptoms at the time of the outbreak. Both groups had detailed renal function testing 3 years after the outbreak, including a random urine albumin to creatinine, glomerular filtration rate estimated by Schwartz formula, and automated and manual blood pressure measurements. Results. There were no baseline differences between the groups with respect to age (mean 4.8 years, range 1 to 15), sex, or birth weight (mean 3.4 kg). In follow-up there were no differences between the groups in body surface area (mean 1.0 m(2)), or in the methods by which renal function was assessed. Compared to the group with no symptoms, patients with HUS demonstrated more microalbuminuria [32% vs. 5%, relative risk 4.8 (95% CI 1.1 to 22.0)], a nonsignificant trend toward lower GFR (124 vs. 134 mL/min per 1.73m(2)), and no difference in blood pressure. Conclusion. Children may demonstrate microalbuminuria 3 years after recovering from HUS. Longer follow-up is needed to determine if this finding has clinical relevance and utility.