Clinicians' confidence in diagnosing atypical anorexia nervosa: An experimental study of the role of patient and clinician characteristics.

Objective: This experimental study investigated the weight loss parameters and resulting end weight that influence clinician confidence in diagnosing atypical anorexia nervosa (AAN).

Methods: Clinicians (N = 67) read a series of vignettes where patient weight loss and end weight varied, then rated their confidence in an AAN diagnosis and alternatives. Using repeated measures ANOVAs, we examined patient (weight loss, end weight) and the possible relationship between clinician (e.g., age, profession) characteristics and confidence in diagnosing AAN.

Results: Clinicians were most confident in an AAN diagnosis when patients had lost 10% or 15% of their body weight, leaving them at a high or normal weight. Clinicians considered 5% as significant weight loss for AAN, but only when the patient ended at a high or normal weight. However, they did not clearly differentiate AAN from unspecified feeding and eating disorder (UFED) when there was a 5% weight loss resulting in high or normal end weight. Clinician characteristics did not impact on confidence in diagnoses.

Conclusion: The DSM's 'significant weight loss' criterion leaves room for clinicians to interpret it idiosyncratically. The lack of a clear pattern of UFED and AAN diagnosis has important clinical implications, as UFED tends to be dismissed as being less serious.