A longitudinal study of gastrointestinal diseases in individuals diagnosed with infantile autism as children.

Background  A number of studies have indicated a link between gastrointestinal (GI) diseases and autism spectrum disorders. Method  The objective of this study was to compare the prevalence and types of GI diseases in a clinical sample of 118 individuals diagnosed as children with infantile autism (IA) with GI diseases in 336 matched controls from the general population, based on data from the nationwide Danish National Hospital Register (DNHR). The average observation time was 30.3 years (SD 0.4) (range 27–30 years), and mean age at the end of the observation period was 42.7 years (SD 7.7) (range between 27 and 57 years of age). Results  Of the 118 individuals with IA, 97 (82.2%) had been in contact with a medical hospital (inpatient hospitalization or outpatient visits) during the observation period, compared with 312/336 (92.9%) in the control group (P= 0.001). A similar proportion of members from the case and comparison group had a diagnosis of any GI disease in the DNHR: 30.5% against 30.7%, but the nature of their diseases may be somewhat different. Only diseases of oral cavity were significantly associated with IA: 20.3% against 1.2%, P < 0.0001. Otherwise, specific GI diseases occurred with low frequency in both groups. Conclusion  Overall, no evidence was found that patients with IA were more likely than control persons without IA to have defined GI diseases during the 30.3-year observation period.