OSFED: Better Definitions Needed

Established diagnostic criteria would help patient care and quality of life.

The DSM-5 category “Other Specified Feeding or Eating Disorders (OSFED)” includes atypical anorexia nervosa (AAN), purging disorder (PD), night eating syndrome (NES), and subthreshold bulimia nervosa and binge eating disorder (Sub-BN/BED). Three clinicians from the University of Melbourne and Murdoch Children’s Research Institute, Melbourne, Australia, have written that the current OSFED diagnostic criteria fall short of accurately describing these conditions, and have overlapping symptoms that can be misleading (Trends in Molecular Med. 2024. 30:403). Authors Dr. Isabel Krug and her colleagues also stress that agreed-upon diagnostic standards for OSFED are needed for consistent study results.

For example, for AAN, the definitions for low weight, weight loss, and the timing of weight loss are inconsistent. For NES, co-morbidity with BED and other sleep-related symptoms has not yet been defined. In addition, symptom frequency and duration have yet to be specified for sub-BN/BED. These are but a few of the areas where diagnosis can be affected.

Another area to consider involves the criteria for NES, and its high comorbidity with BES. Overlapping symptoms between NES and other sleep-related and mood disorders is yet another area of concern. For example, those with NES may have symptoms of insomnia, making it difficult to determine whether the patient has NES or something else. Subthreshold BN and BED involve fewer than weekly binge-eating or purging episodes or episodes that have been present for fewer than 3 months.

According to the authors, the DSM-5 has provided severity ratings for AN, BN, and sub-BN/BED but not for OSFED subtypes (American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders: DSM-5. 2013). According to the authors, the ratings are primarily based on specific diagnostic criteria for AN, BED, and BED. More recent studies have begun exploring alternative severity indices, including the number of purging episodes, which has been helpful as a predictor of eating disorders pathology in individuals with BN. In one study, where a cluster analysis was made of 223 participants with PD, researchers found that those who engage in multiple types of purging behavior, including vomiting and laxative and diuretic use, had more severe eating disorders and general psychopathology than those who only reported vomiting (Int J Eat Disord. 2017. 50:578).

Increased awareness of the five diverse OSFED subtypes and how they differ from AN, BN, and BED is necessary for early and accurate diagnosis, according to the Australian researchers. Establishing the diagnostic criteria for OSFED conditions and applying established diagnostic criteria will help in many ways, including enhancing the quality of life for patients.