Body-mass index and all-cause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents
Creators: name: Willeit, Peter
name: Thompson, Simon G.
name: Gapstur, Susan M.
name: Anopoulou, Eleni Sofi
name: O'Keeffe, Linda M.
name: Green, Jane
name: Barricarte, Aurelio
name: Smith, George Davey
name: Thun, Michael
name: Gao, Pei
name: Fang, Xianghua
name: Jackson, Chandra L.
name: Duk Yun, Young
name: de Gonzalez, Amy Berrington
name: Collins, Rory
name: Gunter, Marc J.
name: Hartge, Patricia
name: Ji Jung, Keum
name: Bhupathiraju, Shilpa N.
name: Di Angelantonio, Emanuele
name: Halsey, Jim
name: Kaptoge, Stephen
name: Yang, Ling
name: Reeves, Gillian K.
name: Ramond, Anna
name: Moore, Steven C.
name: Wormser, David
name: McLerran, Dale F.
name: Paige, Ellie
name: Potter, John D.
name: Lewington, Sarah
name: Cairns, Benjamin J.
name: Manson, JoAnn E.
name: Korda, Rosemary J.
name: Samet, Jonathan M.
name: Carter, Brian
name: Chen, Zhengming
name: Zhou, Maigen
name: Cerhan, James R.
name: Beral, Valerie
name: Lam, Tai-Hing
name: Bansal, Narinder
name: Sacerdote, Carlotta
name: Peto, Richard
name: Hildebrand, Janet S.
name: Joshy, Grace
name: Patel, Alpa V.
name: Zheng, Wei
name: Rolland, Betsy
name: Banks, Emily
name: Woodward, Mark
name: Willett, Walter C.
name: Murphy, Neil
name: Ueshima, Hirotsugu
name: Jee, Sun Ha
name: Hu, Frank B.
name: Franco, Oscar H.
name: Stevens, June
name: Huxley, Rachel
name: Danesh, John
name: Sattar, Naveed
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2016

description: BACKGROUND: Overweight and obesity are increasing worldwide. To help assess their relevance to mortality in different populations we conducted individual-participant data meta-analyses of prospective studies of body-mass index (BMI), limiting confounding and reverse causality by restricting analyses to never-smokers and excluding pre-existing disease and the first 5 years of follow-up.

METHODS: Of 10 625 411 participants in Asia, Australia and New Zealand, Europe, and North America from 239 prospective studies (median follow-up 13·7 years, IQR 11·4-14·7), 3 951 455 people in 189 studies were never-smokers without chronic diseases at recruitment who survived 5 years, of whom 385 879 died. The primary analyses are of these deaths, and study, age, and sex adjusted hazard ratios (HRs), relative to BMI 22·5-<25·0 kg/m(2).

FINDINGS: All-cause mortality was minimal at 20·0-25·0 kg/m(2) (HR 1·00, 95% CI 0·98-1·02 for BMI 20·0-<22·5 kg/m(2); 1·00, 0·99-1·01 for BMI 22·5-<25·0 kg/m(2)), and increased significantly both just below this range (1·13, 1·09-1·17 for BMI 18·5-<20·0 kg/m(2); 1·51, 1·43-1·59 for BMI 15·0-<18·5) and throughout the overweight range (1·07, 1·07-1·08 for BMI 25·0-<27·5 kg/m(2); 1·20, 1·18-1·22 for BMI 27·5-<30·0 kg/m(2)). The HR for obesity grade 1 (BMI 30·0-<35·0 kg/m(2)) was 1·45, 95% CI 1·41-1·48; the HR for obesity grade 2 (35·0-<40·0 kg/m(2)) was 1·94, 1·87-2·01; and the HR for obesity grade 3 (40·0-<60·0 kg/m(2)) was 2·76, 2·60-2·92. For BMI over 25·0 kg/m(2), mortality increased approximately log-linearly with BMI; the HR per 5 kg/m(2) units higher BMI was 1·39 (1·34-1·43) in Europe, 1·29 (1·26-1·32) in North America, 1·39 (1·34-1·44) in east Asia, and 1·31 (1·27-1·35) in Australia and New Zealand. This HR per 5 kg/m(2) units higher BMI (for BMI over 25 kg/m(2)) was greater in younger than older people (1·52, 95% CI 1·47-1·56, for BMI measured at 35-49 years vs 1·21, 1·17-1·25, for BMI measured at 70-89 years; pheterogeneity<0·0001), greater in men than women (1·51, 1·46-1·56, vs 1·30, 1·26-1·33; pheterogeneity<0·0001), but similar in studies with self-reported and measured BMI.

INTERPRETATION: The associations of both overweight and obesity with higher all-cause mortality were broadly consistent in four continents. This finding supports strategies to combat the entire spectrum of excess adiposity in many populations.

FUNDING: UK Medical Research Council, British Heart Foundation, National Institute for Health Research, US National Institutes of Health.