Epidemiology of haemolytic uremic syndrome in children. Data from the North Italian HUS network.

UNLABELLED: Despite the severity of HUS and the fact that it represents a leading cause of acute kidney injury in children, the general epidemiology of HUS is all but well documented. The present study provides updated, population-based, purely epidemiological information on HUS in childhood from a large and densely populated area of northern Italy (9.6 million inhabitants, 1.6 million children). We systematically reviewed the files concerning patients with STEC-HUS and atypical HUS (aHUS) over a 10-year observation period (January 2003-December 2012). We included all incident cases with a documented first episode of HUS before the age of 18 years. We identified 101 cases of HUS during the 10 years. The overall mean annual incidence was 6.3 cases/million children aged <18 years (range 1.9-11.9), and 15.7/million of age-related population (MARP) among subjects aged <5 years; aHUS accounted for 11.9 % of the cases (mean incidence 0.75/MARP). The overall case fatality rate was 4.0 % (3.4 % STEC-HUS, 8.3 % aHUS). CONCLUSION: Given the public health impact of HUS, this study provides recent, population-based epidemiological data useful for healthcare planning and particularly for estimating the financial burden that healthcare providers might have to face in treating HUS, whose incidence rate seems to increase in Northern Italy. WHAT IS KNOWN: • HUS is a rare disease, but it represents the leading cause of acute kidney injury in children worldwide. • STEC-HUS (also called typical, D + HUS) is more common compared to atypical HUS, but recent, population-based epidemiological data (incidence) are scanty. What is New: • Comprehensive, population-based epidemiological data concerning both typical and atypical HUS based on a long observational period.

Hemoconcentration: a major risk factor for neurological involvement in hemolytic uremic syndrome.

BACKGROUND: Shigatoxin-associated hemolytic uremic syndrome (STEC-HUS) is a common thrombotic microangiopathy (TMA) in which central nervous system (CNS) involvement is responsible for the majority of deaths and for severe long-term sequelae. We have analyzed the role of hemoconcentration in disease severity. METHODS: This was a retrospective review of the records and laboratory data at presentation of all patients with STEC-HUS cases (n = 61) over a 10-year period. The patients were grouped into three severity classes: group A, comprising patients who did not require dialysis; group B, patients who were dialyzed without CNS involvement; group C, patients with CNS involvement. RESULTS: Patients with CNS involvement (group C) had a higher mean hemoglobin level (11.2 ± 2.3 g/dL) than those of group A or B ( 9.4 ± 2.1 and 7.5 ± 1.9 g/dL, respectively; p < 0.0001). We also observed that the higher the initial hemoglobin level, the more severe the long-term renal damage (p < 0.007). CONCLUSIONS: In patients with STEC-HUS, hemoconcentration and hypovolemia may be responsible for more severe ischemic organ damage (both short and long term) at disease onset, and these signs should be regarded as risk factors for CNS damage and for more severe TMA. Therefore, we recommend that hydration status should be actively monitored in HUS patients and that dehydration, when diagnosed, should be promptly corrected.