The Global BMI Mortality Collaboration (GBMC) was established to provide reliable estimates of the associations of overweight and obesity with all-cause mortality across populations in major global regions. A pre-specified analysis plan for deriving study-specific estimates from individual-participant data and meta-analysis was agreed among collaborators. Data (or summary results) were sought from large individual prospective studies (defined as ≥100,000 participants recruited at baseline) or large multi-cohort consortia (defined as involving a total of ≥100,000 participants recruited at baseline). The consortium overall involves data from ~10M participants in 239 prospective studies based Asia, Australia and New Zealand, Europe, and North America. In order to limit confounding and reverse causality, pre-specified primary analyses were restricted to data from ~3.95M people in 189 studies who were never-smokers, without chronic diseases at recruitment, and survived for 5 years, The GBMC primary findings have recently been published, revealing that the associations of both overweight and obesity with higher all-cause mortality were broadly consistent across four continents. This finding supports strategies to combat the entire spectrum of excess adiposity in many populations.

Body-mass index and all-cause mortality

Body-mass index and all-cause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents.

Lancet. 2016 Aug 20;388(10046):776-86. [PubMed]