Relation of childhood gastrointestinal disorders to autism: nested case-control study using data from the UK General Practice Research Database.

OBJECTIVES To assess whether children with autism are more likely to have a history of gastrointestinal disorders than children without autism. DESIGN Nested case-control study. SETTING UK General Practice Research Database. SUBJECTS Children born after 1 January 1988 and registered with the General Practice Research Database within 6 months of birth. OUTCOME MEASURES Chronic inflammation of the gastrointestinal tract, coeliac disease, food intolerance, and recurrent gastrointestinal symptoms recorded by the general practitioner. RESULTS 9 of 96 (9%) children with a diagnosis of autism (cases) and 41 of 449 (9%) children without autism (matched controls) had a history of gastrointestinal disorders before the index date (the date of first recorded diagnosis of autism in the cases and the same date for controls). The estimated odds ratio for a history of gastrointestinal disorders among children with autism compared with children without autism was 1.0 (95% confidence interval 0.5 to 2.2). CONCLUSIONS No evidence was found that children with autism were more likely than children without autism to have had defined gastrointestinal disorders at any time before their diagnosis of autism.