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Weight loss predicts complications in anorexia

Study results published in the Journal of Adolescent Health showed that total weight loss and recent weight loss were stronger predictors than admission weight for several important clinical complications in teenagers with restrictive eating disorders.

“In adolescents with [anorexia nervosa (AN) and atypical anorexia nervosa (AAN)], the relative contribution of current weight compared to the total amount of weight loss or recent weight loss on the emergence of physical and psychological complications is unknown,” Melissa Whitelaw, PhD candidate at the Royal Children’s Hospital, Melbourne, Australia, and colleagues wrote.

“The presence of the same physiological complications in AAN as AN suggests that total weight loss (an indication of chronic adaptation to starvation) and recent weight loss (an indication of acute adaptation to starvation) are responsible for these physiological complications as, by definition, adolescents with AAN are not underweight.”

Researchers compared total weight loss and recent weight loss with admission weight as predictors of physical and psychological complications in teenagers aged 12 to 19 years with AN or AAN using data from retrospective (2005 to 2010) and prospective (2011 to 2013) studies. They collected data for each participant via chart review of medical records from day 1 up to 28 days following admission or until discharge.

Predictors of complications included total weight loss (from lifetime maximum), recent weight loss (from past 3 months) and admission weight. The investigators measured hypophosphatemia, clinical, anthropometric and psychometric markers during admission. Participants’ weights were taken twice weekly during hospitalization. Indicators of recent clinical course were biochemistry measures, clinical observations, nutrition prescription, anthropometry, psychotropic use, psychometric measures and length of stay.

In total, 118 participants with AN and 53 with AAN were included in the study, with 41% of participants developing hypophosphatemia, 3% developing hypokalemia and 9% developing hypomagnesemia during admission.

The results showed that greater total weight loss (regression coefficient [Coeff] = –1.7; 95% CI, –2.77 to –0.63) and greater recent weight loss (Coeff = –3.37; 95% CI, –5.77 to –0.97) — but not admission weight — were linked a lower pulse rate nadir in teenagers with AN and AAN. Little evidence supported a connection between weight measures and hypophosphatemia. The strongest predictor overall was total weight loss, according to the study.

In addition, greater total weight loss (OR = 1.7; 95% CI, 1.19-2.24) and recent weight loss (OR = 2.12; 95% CI, 1.11-4.02) were stronger predictors than admission weight for the incidence and severity of bradycardia.

"What we are seeing now is that you can have a healthy body weight but be just as sick as someone with typical anorexia nervosa, including having the same thoughts about eating and food,” Whitelaw said in a press release. "The face of eating disorders is changing against a backdrop of increasing prevalence of overweight and obesity. We need to redefine anorexia because an increasing proportion of anorexia nervosa patients are atypical and more difficult to recognize. The definition should refer to weight loss, not just underweight.” – by Savannah Demko

Disclosure: The authors report no relevant financial disclosures.