From the Guidelines
Hospital admission for anorexia nervosa is typically considered when a patient's BMI falls below 15-16 kg/m², as recommended by recent guidelines 1. When evaluating patients with anorexia nervosa, medical professionals consider multiple factors, including:
- Vital sign abnormalities, such as heart rate below 40 beats per minute or blood pressure below 90/60 mmHg
- Electrolyte imbalances
- Significant ECG changes
- Rapid weight loss, exceeding 1-2 pounds per week
- Failed outpatient treatment
- Psychiatric emergencies
- Severe comorbid conditions The BMI threshold may be higher, around 17-18 kg/m², if these medical complications are present, as noted in the American Psychiatric Association practice guideline for the treatment of patients with eating disorders 1. Hospitalization aims to medically stabilize the patient through careful refeeding protocols, starting at 1,000-1,600 calories daily and gradually increasing by 200-300 calories every few days, while monitoring for refeeding syndrome, as recommended by the APA guideline 1. This approach is necessary because anorexia has the highest mortality rate among psychiatric disorders, with medical complications affecting virtually every organ system, particularly the cardiovascular system, where dangerous arrhythmias can develop from malnutrition and electrolyte disturbances, highlighting the importance of prompt and comprehensive treatment, as emphasized in the guideline 1.
From the Research
Admission Criteria for Anorexia Nervosa
- The decision to admit a patient with anorexia nervosa to a hospital is based on various factors, including the patient's physical and mental health condition 2, 3, 4, 5, 6.
- A study published in 2008 found that patients with a body mass index (BMI) of 13.5 kg/m2 or less were admitted to an inpatient treatment program for severe anorexia nervosa 2.
- Another study published in 2014 surveyed internists and residents-in-training about their admission criteria for patients with anorexia nervosa, and found that the top 5 criteria were:
- Serum potassium levels
- Arrhythmia
- Hypoglycemia
- Heart rate
- Prolonged QT interval on an ECG 3.
- A 2024 study compared hospitalized adult patients with chronic anorexia nervosa with and without prior hospitalizations, and found that most patients achieved weight restoration at program discharge, with a mean discharge BMI of 19.8 kg/m2 4.
- Other studies have highlighted the importance of considering cardiovascular complications in patients with anorexia nervosa, including structural, repolarization/conduction, hemodynamic, and peripheral vascular changes 5, 6.
BMI Thresholds for Admission
- A BMI of 13.5 kg/m2 or less has been used as a threshold for admission to an inpatient treatment program for severe anorexia nervosa 2.
- However, other studies suggest that the decision to admit a patient with anorexia nervosa to a hospital should be based on a comprehensive assessment of their physical and mental health condition, rather than a single BMI threshold 3, 4, 5, 6.