Shared written case formulations and weight change in outpatient therapy for anorexia nervosa: a naturalistic single...

The therapeutic effects of written shared case formulations are underexplored and have not been examined in anorexia nervosa. This study explored the relationship between (a) the delivery (b) the quality of a shared written case formulation and weight in outpatient psychological therapy for anorexia nervosa. A naturalistic single case series approach was used to examine the case notes of women who had attended a specialist eating disorders service over a 2-year period. The case notes of 15 adult women who had undergone outpatient psychological therapy for anorexia nervosa with a shared written case formulation component were reviewed. The impact of the quality of the case formulation on weekly weight was examined for 14 of the clients where the case formulation was available. The nature of the relationship between the delivery of the written shared case formulation and weight was examined for all 15 clients. There was some evidence to support an association between delivery of the shared written case formulation and weight changes (both weight gain [five out of 15 clients] and weight loss [three out of 15 clients]) in individual cases. Higher case formulation quality was related to cases where weight change did not occur. The delivery of case formulations can be associated with important therapeutic change (both beneficial and potentially harmful) in anorexia nervosa. Future research into the causal mechanisms associated with sharing formulations will face the challenge of adopting strategies that allow for an in-depth exploration of complex therapy variables whilst overcoming methodological challenges.