Spatiotemporal burden, dietary risk factors, and genetic causality of high body mass index on low back pain

Low back pain (LBP) is a leading cause of disability worldwide, and high body mass index (BMI) is a modifiable contributor to its burden. We assessed the spatiotemporal burden, dietary context, and genetic evidence linking BMI with LBP. Annual years lived with disability (YLDs) and disability-adjusted life years (DALYs) attributable to high BMI were obtained from the Global Burden of Disease Study 2021 for 1990 to 2021. Trends were evaluated globally, in China, across 6 World Health Organization regions, and across 5 Socio-demographic Index (SDI) quintiles. Estimated annual percentage changes (EAPCs), SDI correlations, and exploratory exponential-smoothing forecasts were calculated. Dietary estimates for 1990 to 2018 were obtained from the Global Dietary Database (GDD). Two-sample Mendelian randomization (MR) was used to evaluate the effect of genetically predicted BMI on LBP. From 1990 to 2021, global DALYs attributable to high BMI increased from 3.09 million to 8.36 million, while the age-standardized DALY rate rose from 70.22 to 97.66 per 1,00,000 population (EAPC 1.14, 95% CI: 1.11–1.17). In China, DALYs increased from 2,45,215.63 to 10,62,017.57 and the rate from 24.34 to 52.70 per 1,00,000 (EAPC 2.89, 95% CI: 2.70–3.09). The global trend was steeper in males than in females ( P  < .001), whereas the difference between Chinese males and females was not statistically significant ( P  = .266). Exploratory forecasts suggested a continued increase in absolute global burden. MR supported a positive association between genetically predicted BMI and LBP (inverse-variance weighted OR 1.007, 95% CI: 1.005–1.009; P  = 6.40 × 10 ^–13 ). GDD estimates showed higher refined-grain intake in East Asia and higher sugar-sweetened beverage intake in the Americas. High BMI contributes to the growing burden of LBP, but the dietary analyses are ecological and should be interpreted as context rather than evidence of mediation. Weight management and region-specific dietary measures may help reduce this burden.