Fracture risk and areal bone mineral density in adolescent females with anorexia nervosa

Abstract

Objective: To (i) compare fracture prevalence in adolescent females with anorexia nervosa (AN) versus normal‐weight controls and (ii) examine whether reductions in areal bone mineral density (aBMD) predict fracture risk in females with AN. Method: Four‐hundred eighteen females (310 with active AN and 108 normal‐weight controls) 12‐ to 22‐years‐old were studied cross‐sectionally. Lifetime fracture history was recorded by a physician during participant interviews. Body composition and aBMD measurements of the whole body, whole body less head, lumbar spine, and hip were assessed by dual‐energy X‐ray absorptiometry, and bone mineral apparent density (BMAD) was calculated for the lumbar spine. Results: Participants with AN and normal‐weight controls did not differ for chronological age, sexual maturity, or height. The lifetime prevalence of prior fracture was 59.8% higher in those with AN as compared to controls (31.0% vs. 19.4%, p = 0.02), and the fracture incidence rate peaked in our cohort after the diagnosis of AN. Lower aBMD and lumbar BMAD were not associated with a higher prevalence of fracture in the AN or control group on univariate or multivariate analyses. Compared to controls, fracture prevalence was significantly higher in the subgroup of girls with AN who had normal aBMD or only modest reductions of aBMD (Z‐scores > −1 or −1.5). Discussion: This is the first study to show that the risk of fracture during childhood and adolescence is significantly higher in patients with AN than in normal‐weight controls. Fracture prevalence is increased in this cohort of participants with AN even without significant reductions in aBMD. © 2014 Wiley Periodicals, Inc. (Int J Eat Disord 2014; 47:458–466)