Predictive Effect of Preoperative Bone Marrow Fat Fraction on Postoperative Bone Mineral Density After Bariatric Surgery: a Prospective Cohort Study.

OBJECTIVE

To investigate changes in volumetric bone mineral density (vBMD) and bone marrow fat fraction (BMFF), as well as to identify the relationship between vBMD and BMFF before and after bariatric surgery.

METHODS

One hundred and fifty-eight obese patients who underwent bariatric surgery were prospectively included. vBMD and BMFF of the lumbar spine were quantified at baseline and one year using quantitative computed tomography and iterative decomposition of water and fat with echo asymmetry and least squares estimation quantification magnetic resonance imaging. Anthropometric, biochemical and body-composition variables were collected simultaneously. Multivariate regression analysis was used to identify potential determinants of vBMD.

RESULTS

Significant differences were found in weight, body mass index, vBMD, body compositions, BMFF and laboratory parameters (except for total cholesterol and low-density lipoprotein cholesterol levels) (all P < 0.05). In univariate and multivariate regression analyses, no statistically significant factors for change in vBMD were found, while higher preoperative BMFF independently predicted lower postoperative vBMD (β = -1.154, 95% confidence interval − 2.085 to -0.224, P < 0.05), and this association was further validated to be robust and statistically significant in the SG-only subgroup sensitivity analysis (β = -1.690, 95% confidence interval − 2.941 to -0.440, P < 0.05).

CONCLUSIONS

Our findings revealed that both vBMD and BMFF decreased one year after surgery. The higher the preoperative BMFF level, the lower the postoperative vBMD level, especially in the SG-only subgroup. This indicates that preoperative BMFF can be served as a candidate predictor of postoperative bone mass changes in obese patients.