Estimated burden of rotavirus-associated diarrhea in ambulatory settings in the United States.

BACKGROUND: Two vaccines to prevent disease from rotavirus among young children were recently approved in the United States. Although previous studies of the burden of rotaviral disease have focused on hospitalizations, the assessment of baseline disease burden in ambulatory settings is useful for evaluating the overall impact of the vaccine.
METHODS: Outpatient and emergency department (ED) data for 1994-2006 were analyzed from 2 nationally representative databases: the National Ambulatory Medical Care Survey and the National Hospital Medical Care Survey. Visits by children (younger than 5 years) with acute gastroenteritis (AGE) were identified by using a defined set of International Classification of Diseases, Ninth Revision, Clinical Modification codes. Two previously described methods (the winter-residual-excess [WRE] and Brandt methods) were used to estimate the proportion of AGE attributable to rotavirus and to determine the annual number of visits, annual average visits, and annual visit rates in each setting.
RESULTS: The estimated average annual number of rotavirus-associated visits over the 13-year period was 782 453 outpatient visits and 164 261 ED visits from the WRE method and 665 773 outpatient visits and 205 206 ED visits from the Brandt method. This resulted in an average of 39.1 and 33.3 outpatient visits per 1000 children and 8.2 and 10.3 ED visits per 1000 children for both the WRE and Brandt methods, respectively. The average annual proportion of visits for AGE attributed to rotavirus was 34.2% (29.1% from the Brandt method) in the outpatient setting and 21.8% (27.1% from the Brandt method) in the ED, with wide variations in individual years.
CONCLUSIONS: Before the rotavirus vaccine, rotavirus seemed to be associated with a large number of outpatient and ED visits among young children. Rotavirus vaccine has the potential to reduce many outpatient and ED visits.