Limitations of body mass index to assess body composition due to sarcopenic obesity during leukemia therapy

Abstract

Obesity as defined by body mass index percentile (BMI%) is strongly associated with relapse and poorer survival in childhood ALL. Whether BMI% accurately reflects body fat percentage (BF%) in this population is unknown. We conducted a prospective study assessing body composition during frontline ALL therapy. Dual-energy X-ray absorptiometry measured BF% and lean muscle mass (LMM) at diagnosis, end of Induction, and end of Delayed Intensification. Sarcopenic obesity (gain in BF% with loss of LMM) was surprisingly common during ALL treatment, resulting in poor correlation between changes in BMI% (expressed as Z-score) and BF% overall (r = −0.05) and within patients (r = −0.09). BMI Z-score and BF% changed in opposite directions in >50% of interval assessments. While BMI% at diagnosis is a suitable predictor of obesity/BF% for epidemiological studies, change in BMI% (as expressed as Z-score) does not reflect body composition. Studies evaluating obesity in leukemia should consider using direct measures of body composition.

Keywords:

• Adiposity
• body fat
• body mass index
• childhood ALL
• DXA scan
• obesity

Potential conflict of interest

Disclosure forms provided by the authors are available with the full text of this article at https://doi.org/10.3109/10428194.2015.1136741.

The authors report that they have no conflicts of interest. This work was supported by a Translational Research Program grant from the Leukemia and Lymphoma Society (LLS-6249-11), Hyundai Hope on Wheels Foundation, the National Center for Advancing Translational Sciences/NIH (UL1TR000130) via the Southern California Clinical and Translational Science Institute, and funds from The Saban Research Institute.