Effect of Definitions of Acute Gastroenteritis Episodes using Symptom Diaries in Paediatric Cohorts: A Systematic Review.

Estimates of acute gastroenteritis (AGE) burden are difficult to compare between studies because of inconsistent definitions describing this illness. AGE definitions used in prospective, community-based childhood cohort studies were identified by searching databases for studies that collected daily observations of AGE symptoms. Disease definitions and refractory periods were extracted. Data from the Australian community-based Observational Research in Childhood Infectious Diseases (ORChID) birth cohort were used to calculate AGE incidence and duration using identified AGE definitions, and the World Health Organization definition for diarrhoea. Eight distinct AGE definitions were identified. All included loose stools and seven included vomiting as symptoms. The refractory period separating episodes ranged from 1 to 21 days. When applied to the ORChID dataset, AGE incidence ranged from 0.8 to 2.6 episodes per child-year-at-risk, a threefold relative difference. Direct comparisons of rates from different cohorts can only be undertaken if a standard definition for AGE is adopted.