Rate of weight gain of inpatients with anorexia nervosa under two behavioral contracts

Abstract

Objective: To ascertain the rate of weight gain of inpatients with anorexia nervosa under two behavioral contracts, differing in criterion weight gain required to earn increasing privileges.

Design: Follow-up comparison of cohorts receiving different interventions.

Setting: Eating disorders service, operating on a general adolescent medicine unit.

Patients: Patients admitted consecutively who met the following criteria: (1) weight at least 15% less than that expected for age, sex, and height; (2) female gender; (3) absence of chronic medical illness; (4) hospital stay of at least 28 days. Twenty-two patients meeting these criteria were treated between July 1987 and October 1988, when contract 1 was in effect. This cohort of patients was compared with a group of 31 patients, also meeting the these criteria, who were treated between November 1988 and December 1991, when contract 2 was in effect.

Interventions: The behavioral contract, signed by the patient on admission, specifies the minimum 4-day weight gain necessary to earn increasing ward privileges, such as use of phone, frequency of visits, etc. Contracts 1 and 2 differed only in the 4-day weight gain criterion: 0.8 lb (0.36 kg) and 1.2 lb (0.55 kg), respectively.

Results: The results of analysis of covariance, with admission weight as the covariate, revealed a significant interaction between contract and day, such that patients receiving contract 2 gained weight more rapidly (0.36 lb/d) than those receiving contract 1 (0.20 lb/d). There was no confounding difference between groups in the use of psychotropic medication, and no complications of refeeding in either group.

Conclusion: Increasing the 4-day criterion weight gain from 0.8 to 1.2 lb in a behavioral contracting intervention was associated with a significant increase in the rate of weight gain, without an accompanying increase in complications of refeeding. This result simultaneously: (a) provides support for the efficacy of behavioral contracting and (b) reveals malleability in the rate of gain based on the targeted gain specified in the contract.