Global burden of high BMI-related osteoarthritis and causal effects of obesity: a GBD 1990–2021 and bidirectional two-sample Mendelian randomization study

BACKGROUND: Osteoarthritis is the most prevalent joint disorder, and osteoarthritis associated with high BMI contributes significantly to the global disease burden. The aim of this study is to elucidate the burden of BMI-related osteoarthritis and to investigate the causal relationship between varying degrees of obesity and osteoarthritis. METHODS: The Global Burden of Disease (GBD) 2021 study was used to conduct an epidemiological analysis of osteoarthritis. This included descriptive statistics, age-sex differences, Joinpoint regression analysis, burden sources and control measures, and projections up to 2050. A two-sample Mendelian randomization analysis was also performed to explore the relationship between obesity and osteoarthritis. RESULTS: Osteoarthritis burden rose from 1990 to 2021, affecting younger populations, though there was a decline in regions with a high Socio-demographic Index (SDI) between 2001 and 2005. Women experienced a greater burden than men. The increase in disease burden was driven by population growth and rising disease prevalence. There is considerable potential for enhancing osteoarthritis control in most countries. Forward Mendelian randomization analyses demonstrated a significant causal relationship between obesity and osteoarthritis, whereas inverse Mendelian randomization analyses found no evidence of causality from osteoarthritis to obesity at any obesity level. CONCLUSION: The global rise in disability-adjusted life-years (DALYs) due to BMI-related osteoarthritis mainly due to population growth, affecting women more than men. This study may be a reference point for early and precise intervention in BMI-related osteoarthritis.