Modern Trends in Demographics, Extrarenal Manifestations, and Inpatient Healthcare Utilization for Hemolytic Uremic Syndrome in the U.S.A.

Background: Hemolytic-uremic syndrome (HUS) is characterized by a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure.  Extrarenal manifestations complicate HUS, damaging the gastrointestinal tract, central nervous system, and respiratory tract.  Despite these potentially serious sequelae, there have been few studies characterizing the demographics, clinical outcomes and the economic burden of HUS.  This study aims to describe modern trends of HUS in the United States since 2000 as well as factors that influence length of hospitalization and predictors of dialysis and mortality. Methods: Pediatric admissions with a primary diagnosis of HUS between 2000 and 2009 were evaluated via the Kids’ Inpatient Database of the Healthcare Utilization Project. Results: From 2000-2009, approximately 1,133 children were hospitalized annually with HUS.  Despite increased hospital charges, overall hospital length of stay (LOS) decreased significantly between 2000 and 2009.  Females predominated slightly (53.7%), and children between ages 1-4 years accounted for 49.1% of HUS patients.   Extra-renal manifestations, including pancreatitis, neurologic and respiratory complications, and sepsis, were associated with increased likelihood of requiring dialysis.  Almost one-third of HUS patients received red blood cell (RBC) transfusions, and RBC transfusion frequency increased over time.  The overall mortality rate was 2.4%, and significantly decreased over time.  Neurologic and respiratory complications and sepsis were associated with increased mortality. Conclusions: Despite the serious complications, invasive procedures, and mortality associated with HUS, there is a lack of data describing the demographics and impact of HUS on the healthcare system in the USA.  This study fills this void by providing the largest review of HUS cases worldwide to date, and will provide impetus to prospective evaluation of interventions to reduce morbidity and mortality in children with this disease. Keywords: Hemolytic uremic syndrome, dialysis, pancreatitis, neurologic complications