Time Course of Relapse Following Acute Treatment for Anorexia Nervosa

Abstract

Objective: There is long-standing interest in how best to define stages of illness for anorexia nervosa, including remission and recovery. The authors used data from a previously published study to examine the time course of relapse over the year following full weight restoration.

Methods: Following weight restoration in an acute care setting, 93 women with anorexia nervosa were randomly assigned to receive fluoxetine or placebo and were discharged to outpatient care, where they also received cognitive-behavioral therapy for up to 1 year. Relapse was defined on the basis of a priori clinical criteria. Fluoxetine had no impact on the time to relapse. In the present analysis, for each day after entry into the study, the risk of relapse over the following 60 days and the following 90 days was calculated and a parametric function was fitted to approximate the Kaplan-Meier estimator.

Results: The risk of relapse rose immediately after entry into the study, reached a peak after approximately 60 days, and then gradually declined. There was no indication of an inflection point at which the risk of relapse fell precipitously after the initial peak.

Conclusions: This analysis highlights the fact that adult patients with anorexia nervosa are at increased risk of relapse in the first months following discharge from acute care, suggesting a need for frequent follow-up and relapse prevention-focused treatment during this period. After approximately 2 months, the risk of relapse progressively decreases over time.

Keywords: Anorexia Nervosa; Feeding and Eating Disorders; Outcome Studies; Relapse; Remission.

Figures

Figure 1.

Probability of relapse in the next 60 days versus time after study entry. The line in grey is the step function showing the nonparametric Kaplan Meier estimator. The fitted gamma function is shown by the black line; the dashed lines show the 95% confidence intervals. The fitted parameters are α^=−0.0131 (95% CI: −0.0134, −0.0128), γ^=0.0069 (95% CI: 0.0066, 0.0071), and c^=−10.19 (95% CI: −11.98, −8.41). At day 0, the probability of relapse within next 60 days was 6.6% ± 1.5%. The maximum risk of relapse was on day 66 when the probability was 19.3% ± 1.4%. After day 268, the relapse risk declined to below 5%.

Figure 2.

Probability of relapse in the next 90 days versus time after study entry. The line in grey is the step function showing the nonparametric Kaplan Meier estimator. The fitted gamma function is shown by the black line; the dashed lines show the 95% confidence intervals. The fitted parameters are α^=−0.0127 (95% CI: −0.0130, −0.0125), γ^=0.0093 (95% CI: 0.0090, 0.0095), and c^=−24.25 (95% CI: −26.36, −22.13). At day 0, the probability of relapse within next 90 days was 17.0% ± 1.5%. The maximum risk of relapse was on day 54 when the probability was 26.8% ± 1.4%. After day 297, the relapse risk declined to below 5%.