Similarities and Differences of Inpatients With Anorexia Nervosa or Atypical Anorexia Nervosa

Anorexia nervosa (AN) and atypical AN (AAN) are associated with significant malnutrition. However, AAN symptomatology may be underestimated, and further research is required regarding inpatient presentations. We aimed to describe demographic and clinical characteristics of psychiatric inpatients with AN or AAN at the Eating Disorders Unit, Austin Hospital in Melbourne, Victoria, Australia. Retrospective review of patient files was undertaken for inpatients aged 18 to 65 years with an eating disorder who resided within the Body Image & Eating Disorders Treatment & Recovery Service catchment area and were admitted to Eating Disorders Unit between January 1, 2021, and October 30, 2023. Among 91 patients with AN and 40 patients with AAN, demographic and clinical characteristics were primarily similar across both groups. The AN group had a greater proportion of a severe malnutrition diagnosis and medical comorbidity. The AAN group was managed on prescribed meal plans with lower total daily kilojoule intake and on average had shorter admissions. Despite this, both groups showed similar outcomes in relation to emergency medical reviews for medical instability. AAN and AN can both result in significant medical instability, which requires urgent medical assessment and treatment. Malnutrition assessment should focus on variables such as vital signs, pathology results, eating disorder cognitions/behaviors, and the trajectory of weight loss in addition to current body mass index. AN and AAN are both conditions that demonstrate physical and mental health needs that benefit from multidisciplinary assessment and management.