BODY-WEIGHT IN ACUTE ANOREXIA-NERVOSA AND AT FOLLOW-UP ASSESSED WITH PERCENTILES FOR THE BODY-MASS INDEX - IMPLICATIONS OF A LOW BODY-WEIGHT AT REFERRAL

Objective: A systematic epidemiological comparison of body weights of patients with anorexia nervosa can be enhanced by the use of age perce ntiles for the body mass index. Method: To demonstrate the feasibility of this approach, body mass indices of 81 female adolescents with ano rexia nervosa were calculated from anthropometric data upon admission for inpatient treatment and at follow-up and set into relationship to the age-dependent distribution of the body mass index in a large and r epresentative sample of the German population. The percentiles were us ed to visualize the weight increase over time of each former patient b y aligning the body mass index at referral with the respective body ma ss index at follow-up. Results: Upon admission most adolescents had bo dy mass indices below the third age centile. The distribution of body mass indices at outcome suggests a continuum between death of complica tions related to starvation, chronic anorexia, residual anorexia, and a low body weight. Patients with very low body weights at referral had a poor prognosis, because their body weights tended to remain below t he minimal normal weight for height. These conditions were statistical ly best described by categorial analysis, because they were nonlinear to a certain extent. Discussion: The results indicate that the body ma ss index at referral influences the amount of weight that an individua l patient gains in the future. (C) 1996 by John Wiley & Sons, Inc.