Relationships between anthropometric adiposity indexes and bone mineral density in a cross-sectional Chinese study

Background context: Previous studies have reported conflicting results for the relationships between anthropometric adiposity indexes and bone mineral density, based on dual-energy X-ray absorptiometry (DXA). However, few studies were published based on quantitative computed tomography (QCT), especially for Chinese population.

Purpose: To evaluate the associations of spine bone mineral density (BMD) with body mass index (BMI), waist circumstance (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) and a body shape index (ABSI) using QCT.

Study design/setting: A Cross-sectional study.

Patient sample: Around 3,457 participants in multiple communities across 7 administrative regions of China.

Outcome measures: Spine BMD was measured using QCT, and the classification of osteoporosis was defined as follows: 1) osteoporosis if BMD <80mg/cm³, 2) osteopenia if BMD 80-119 mg/cm³, and 3) normal bone mass if BMD≥120 mg/cm³.

Methods: This study was conducted using convenient sampling between 2013 and 2017. Multivariable linear regression model and logistic regression models were used for the associations of continuous and categorical BMD, respectively.

Results: Around 3,405 participants were included in the final analyses, including 1,272 males and 2,133 females, with spine BMD of 111.00±35.47 mg/cm³ and 99.38±40.60 mg/cm³, respectively. Spine BMD decreased significantly with the increase of ABSI in females (adjusted β, -5.74; 95% confidence interval [CI], -8.50 to -2.98), and this trend also was kept in females aged at less than 60 years (adjusted β, -14.54; 95% CI, -20.40 to -8.68), and females with age ≥60 years (adjusted β, -7.59; 95% CI, -10.91 to -4.28). However, this inverse association was observed only in males with age ≥ 60 years (adjusted β, -5.19; 95% CI, -10.08 to -0.29). Except ABSI, negative associations of Spine BMD with WC (adjusted β, -0.46; 95% CI, -0.77 to -0.15), WHR (adjusted β, -6.25; 95% CI, -10.63 to -1.86), WHtR (adjusted β, -6.80; 95% CI, -11.63 to -1.97) were shown in females aged at <60 years, and positive association with BMI in males with age ≥60 years (adjusted β, 0.92; 95% CI, 0.29-1.55).

Conclusions: ABSI had more remarkable association with spine BMD, compared with the other four indexes.