Comparing operational definitions of DSM-5 anorexia nervosa for research contexts.

OBJECTIVE

DSM-5 anorexia nervosa (AN) criteria include several changes that increase reliance on clinical judgment. However, research contexts require operational definitions that can be applied reliably and that demonstrate validity. The present study evaluated different operational definitions for DSM-5 AN.

METHOD

DSM-5 AN criteria were applied to diagnostic interview data from 364 women varying two features: threshold for determining low weight for Criterion A (body mass index [BMI] <17.0 kg/m(2) vs. <18.5 kg/m(2)) and explicit endorsement of weight phobia (Criterion B explicit vs. inferred). Resulting groups of individuals with DSM-5 AN were compared on estimated frequency. In addition, AN groups were compared to non-eating disorder controls and individuals with an other specified feeding or eating disorder (OSFED) on external validators.

RESULTS

All operational DSM-5 definitions produced higher lifetime frequency estimates than reported for DSM-IV AN, with a particularly large increase associated with the broadest definition. All definitions produced significant differences in comparison to controls on external validators that were associated with medium to large effect sizes. Only definitions that required a lower weight threshold or explicit endorsement of weight phobia demonstrated significant differences compared to OSFED on external validators, and these were of small effect size. The specific combination of BMI <18.5 kg/m(2) with inferred weight phobia exhibited few meaningful distinctions from the OSFED group.

DISCUSSION

To balance inclusivity, syndromal reliability, and validity, an operational definition for DSM-5 AN in research contexts should define low weight as BMI <18.5 kg/m(2) and require measurable rather than inferred weight phobia.