Diagnosing metabolic syndrome in craniopharyngioma patients: body composition versus BMI

in European Journal of Endocrinology
Correspondence should be addressed to S S van Santen; Email: s.vansanten@erasmusmc.nl
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Objective

Craniopharyngioma patients often have poor metabolic profiles due to hypothalamic–pituitary damage. Previously, using BMI as obesity marker, the occurrence of the metabolic syndrome in these patients was estimated at 46%. Our aim was to determine if dual X-ray absorptiometry (DXA) scan in evaluation of obesity and metabolic syndrome would be superior.

Design

Retrospective study of craniopharyngioma patients for whom DXA scan results were available.

Methods

BMI, fat percentage and fat mass index were used to evaluate obesity and as components for obesity in metabolic syndrome.

Results

Ninety-five craniopharyngioma patients were included (51% female, 49% childhood-onset disease). Metabolic syndrome occurred in 34–53 (45–51%) subjects (depending on the definition of obesity, although all definitions occurred in higher frequency than in the general population). Metabolic syndrome frequency was higher if obesity was defined by fat percentage (52 vs 42%) or fat mass index (51 vs 43%) compared to BMI. Misclassification appeared in 9% (fat percentage vs BMI) and 7% (fat mass index vs BMI) for metabolic syndrome and 29 and 13% for obesity itself, respectively. For metabolic syndrome, almost perfect agreement was found for BMI compared with fat percentage or fat mass index. For obesity, agreement was fair to moderate (BMI vs fat percentage).

Conclusion

Using BMI to evaluate obesity underestimates the true prevalence of metabolic syndrome in patients with craniopharyngioma. Furthermore, fat percentage contributes to a better evaluation of obesity than BMI. The contribution of DXA scan might be limited for identification of the metabolic syndrome.

Downloadable materials

  • Supplementary Table 2: Included Dual X-ray Absorptiometry scanners
  • Supplementary Table 1: Comparison of craniopharyngioma patients with and without DXA-scan.
  • Supplementary Table 3: Metabolic syndrome and its components in patients with craniopharyngioma
  • Supplementary Table 4: Bland-Altman bias of BMI SDS and BF%/FMI SDS scores at first and last DXA-scan.
  • Supplementary Table 5: Agreement of anthropomorphic measurements and DXA-scan for evaluation of obesity and metabolic syndrome.
  • Supplementary Table 6 – Risk factors for the metabolic syndrome in patients with craniopharyngioma
  • Supplementary Figure 1: BMI versus body fat percentage and FMI in overweight subjects.

 

     European Society of Endocrinology

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Figures

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    BMI vs body fat percentage (BF%) and fat mass index (FMI) at first (AC) and last (BD) DXA scan in craniopharyngioma patients. Obesity based on BF% or FMI are bordered by the blue vertical line for males and by the red vertical line for females on the X-axis. The purple horizontal line borders obesity based on BMI. Female and male patients in the right lower quadrant are considered obese by fat percentage/FMI, but not by BMI.

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    Bland–Altman plots. Plot (A) and (B) present data on the first DXA scan; plot (C) and (D) of the last DXA scan. Respectively, on the X-axis the average, and on the Y-axis the difference is expressed of BMI standardized deviation scores (SDS) and body fat percentage SDS (AC) or fat mass index SDS (BD). An upward trend is seen in the difference of the average for BF% at first and last DXA scan (AC). The difference in SDS of BMI and BF% seems larger at the end of the ranges, since the differences are observed outside the 95% agreement interval. These suggested discrepancies appear mostly in the upper and lower end of the ranges. For the difference of the average for FMI, the upward trend is not obviously shown.

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