PurposeTo determine the clinical characteristics and course of severe avoidant/restrictive food intake disorder (ARFID) in hospitalized children and adolescents and compare them with those of patients with restricting-type anorexia nervosa (R-AN).Patients and methodsWe conducted a retrospective chart review of inpatients diagnosed with ARFID or R-AN based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, at Jichi Children’s Medical Center Tochigi between April 1, 2007 and March 31, 2017. We compared the characteristics of the ARFID and R-AN patients at admission, during hospitalization, and after discharge.ResultsBoth the ARFID (n=13) and R-AN (n=79) patients required hospitalization for their medically unstable state. The features of ARFID group included concern about the aversive consequences of eating and avoidance of eating due to sensory concerns. Significant differences were found at admission between ARFID and R-AN groups in age (10.7 vs 12.7 years), family history of mental disorders (46.2% vs 17.7%), comorbid developmental disorders (6 vs 3 cases), and the time from onset to admission (3.9 vs 6.3 months). The body weight status, % ideal body weight (%IBW), % expected body weight (%EBW), <75% IBW rate, and <75% EBW rate did not differ significantly between the two groups at admission or discharge. The duration of post-discharge outpatient follow-up treatment did not differ significantly between ARFID and R-AN groups (15.3 vs 18.4 months); however, ARFID group recovery rate was significantly higher than that of R-AN group (77% vs 43%). The reasons that the patients with ARFID had significantly better outcomes than the R-AN patients remain unclear. Compared to those in previous studies, the present patients were younger and demonstrated better outcomes. Our results indicate that the body weight status is similar between ARFID and R-AN patients, but the ARFID patients achieved better outcomes.ConclusionThese findings suggest that early onset in childhood, early disease recognition, and early intervention are important factors for achieving better outcomes for patients with ARFID.