IMPORTANCE: Avoidant restrictive food intake disorder (ARFID) is a feeding and eating disorder characterized by limited variety and/or quantity of food intake impacting physical health and psychosocial functioning. Children with ARFID often present with diverse psychiatric and somatic symptoms and therefore consult various pediatric subspecialties. Large-scale studies mapping coexisting conditions are, however, lacking. OBJECTIVE: To characterize the health care needs of youth with ARFID. DESIGN, SETTING, AND PARTICIPANTS: This cohort study used the Child and Adolescent Twin Study in Sweden (CATSS), in combination with inpatient and specialized outpatient clinical diagnoses from the Swedish National Patient Register. Data were collected from July 2004 to April 2020, and data were analyzed from September 2022 to February 2024. EXPOSURE: Using a composite measure derived from parent or guardian reports and register data, children with the broad ARFID phenotype occurring between the ages of 6 to 12 years were identified, as well as children without ARFID. MAIN OUTCOMES AND MEASURES: From more than 1000 diagnostic International Classification of Diseases (ICD) codes, mental and somatic conditions within or across ICD chapters, the number of distinct per-person diagnoses, and inpatient treatment days between participants' birth and 18th birthdays were specified (90 outcomes). Hazard ratios (HRs) and incidence rate ratios (IRRs) were calculated. RESULTS: Of 30 795 CATSS participants, a total of 616 children (2.0%) with the broad ARFID phenotype occurring between the ages of 6 to 12 years were identified, and 30 179 children without ARFID were identified. Of 616 children with ARFID, 241 children were female (39.1%). Relative risks of neurodevelopmental, gastrointestinal, endocrine or metabolic, respiratory, neurological, and allergic disorders were substantially increased in children with ARFID (eg, autism: HR, 9.7
95% CI, 7.5-12.5
intellectual disability: HR, 10.3
95% CI, 7.6-13.9
gastroesophageal reflux disease: HR, 6.7
95% CI, 4.6-9.9
pituitary conditions: HR, 5.6
95% CI, 2.7-11.3
chronic lower respiratory diseases: HR, 4.9
95% CI, 2.4-10.1
and epilepsy: HR, 5.8
95% CI, 4.1-8.2). ARFID was not associated with elevated risks of autoimmune illnesses and obsessive-compulsive disorder. Children with ARFID had significantly more distinct mental diagnoses (IRR, 4.7
95% CI, 4.0-5.4) and longer hospital stays (IRR, 5.5
95% CI, 1.7-17.6) compared with children without ARFID. Children with ARFID were diagnosed with a mental condition earlier than children without ARFID. No sex-specific differences emerged. CONCLUSIONS AND RELEVANCE: This cohort study yields the broadest and most detailed evidence of coexisting mental and somatic conditions in the largest sample of children with ARFID to date. Findings suggest a complex pattern of health needs in youth with ARFID, underscoring the critical importance of attention to the illness across all pediatric specialties.