Central fatness and risk of all cause mortality: systematic review and dose-response meta-analysis of 72 prospective cohort studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of prospective observational cohort studies
PubMed 32967840 · doi:10.1136/bmj.m3324
What was done
A systematic review and dose-response meta-analysis was conducted using PubMed and Scopus searches from inception to July 2019. The authors included prospective cohort studies reporting risk estimates of all-cause mortality in the general population across at least three categories or as continuous variables for indices of central fatness (waist circumference, hip circumference, thigh circumference, waist-to-hip ratio, waist-to-height ratio, waist-to-thigh ratio, body adiposity index, and A body shape index). Random-effects models assessed linear trends, and one-stage linear mixed-effects models estimated dose-response curves.
What was found
Across 72 prospective cohort studies comprising 2,528,297 participants, summary hazard ratios for all-cause mortality were: waist circumference per 10 cm increase: 1.11 (95% CI 1.08 to 1.13, I2 = 88%, n = 50); hip circumference per 10 cm increase: 0.90 (95% CI 0.81 to 0.99, I2 = 95%, n = 9); thigh circumference per 5 cm increase: 0.82 (95% CI 0.75 to 0.89, I2 = 54%, n = 3); waist-to-hip ratio per 0.1 unit increase: 1.20 (95% CI 1.15 to 1.25, I2 = 90%, n = 31); waist-to-height ratio per 0.1 unit increase: 1.24 (95% CI 1.12 to 1.36, I2 = 94%, n = 11); waist-to-thigh ratio per 0.1 unit increase: 1.21 (95% CI 1.03 to 1.39, I2 = 97%, n = 2); body adiposity index per 10% increase: 1.17 (95% CI 1.00 to 1.33, I2 = 75%, n = 4); and A body shape index per 0.005 unit increase: 1.15 (95% CI 1.10 to 1.20, I2 = 87%, n = 9). Positive associations persisted after adjusting for body mass index. Waist circumference and waist-to-height ratio exhibited nearly J-shaped dose-response curves; waist-to-hip ratio and A body shape index showed positive monotonic associations; body adiposity index showed a U-shaped association.
Why it matters
Central fat accumulation provides prognostic mortality information beyond body mass index, supporting the routine measurement of central adiposity alongside standard BMI to assess premature death risk.
Limits
Statistical heterogeneity was extremely high across most analyses, with I2 values frequently exceeding 85% to 90%. Being an observational meta-analysis, causality cannot be definitively proven and residual confounding remains possible. Several specific anthropometric indices relied on very few cohorts (thigh circumference n = 3, waist-to-thigh ratio n = 2, body adiposity index n = 4).
Cited by
- supports Fat accumulated on the abdomen poses greater health risks than fat on the legs or arms.