Background: The aim of the present study was to provide benchmark data on the duration of treatment required to restore body weight (to BMI ≥18.5 or a corresponding BMI centile) in adolescents and adults with anorexia nervosa treated with outpatient cognitive behaviour therapy.
Methods: Ninety-five participants (46 adolescents and 49 adults) were recruited from consecutive referrals to a specialist eating disorder clinic. Each was offered 40 sessions of enhanced cognitive behaviour therapy (CBT-E) over 40 weeks, the conventional length of this treatment.
Results: Twenty-nine (63.1%) of the adolescents and 32 (65.3%) of the adults completed all 40 sessions of treatment (P = 0.818). Significantly more adolescents reached the goal BMI than adults (65.3% vs. 36.5%; P = 0.003). The mean time required by the adolescents to restore body weight was about 15 weeks less than that for the adults (14.8 (SE = 1.7) weeks vs. 28.3 (SE = 2.0) weeks, log-rank = 21.5, P < 0.001).
Conclusions: The findings indicate that adolescent patients receiving CBT-E are able to regain weight more successfully than adults and at a faster rate. If these findings are replicated and extend to eating disorder psychopathology, then their treatment could be shorter than that of adults.
Keywords: Anorexia nervosa; Cognitive behaviour therapy; Eating disorder; Outcome; Treatment.