Convalescent resting tachycardia predicts unfavorable outcome of anorexia nervosa

Background: In patients with anorexia nervosa (AN) who have tachycardia during the clinical course, difficulty in treatment has been observed. The purpose of the present study was to evaluate the association between heart rate (HR) in the weight loss and weight recovery periods, and outcome. Methods: The subjects consisted of 40 girls with AN (age at onset, 8-16 years). The outcome 1-5 years after the initiation of treatment was regarded as favorable for both bodyweight within 15% of the standard weight and regular menstruation during the last 6 months, and unfavorable for bodyweight <85% of the standard weight and absent or nearly always absent menstruation. HR during the weight loss period was obtained at the outpatient clinic on the first visit. For HR during the weight recovery period, we used the resting and peak HR obtained in exercise tolerance test, which was performed when the bodyweight successfully increased along with improvement in physical complications. The association between each HR and outcome was evaluated. Results: Favorable outcomes were observed in 19 of the 40 patients after the 1 year follow up but in 32 after the 5 year follow up. Resting HR during the weight recovery period was higher throughout the 5 years in the unfavorable than in the favorable outcome group, with significant differences after the 2, 4, and 5 year follow ups. Conclusion: In AN, resting tachycardia during the convalescent period is associated with unfavorable outcome.