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Heavier smoking may lead to a relative increase in waist circumference: evidence for a causal relationship from a Mendelian randomisation meta-analysis. The CARTA consortium

2015; BMJ; Volume: 5; Issue: 8 Linguagem: Inglês

10.1136/bmjopen-2015-008808

2044-6055

Richard Morris, Amy E. Taylor, Meg Fluharty, Johan Hå‌kon Bjø‌rngaard, Bjørn Olav Åsvold, Maiken E. Gabrielsen, Archie Campbell, Riccardo E. Marioni, Meena Kumari, Tellervo Korhonen, Satu Männistö, Pedro Marques‐Vidal, Marika Kaakinen, Alana Cavadino, Iris Postmus, Lise Lotte N. Husemoen, Tea Skaaby, Tarun Ahluwalia, Jorien L. Treur, Gonneke Willemsen, Caroline Dale, S. Goya Wannamethee, Jari Lahti, Aarno Palotie, Katri Räikkönen, Alex McConnachie, Sandosh Padmanabhan, Andrew Wong, Christine Dalgård, Lavinia Paternoster, Yoav Ben‐Shlomo, Jessica Tyrrell, L. John Horwood, David M. Fergusson, Martin A. Kennedy, Ellen A. Nøhr, Lene Christiansen, Kirsten Ohm Kyvik, Diana Kuh, Graham Watt, Johan G. Eriksson, Peter H. Whincup, Jacqueline M. Vink, Dorret I. Boomsma, George Davey Smith, Debbie A. Lawlor, Allan Linneberg, Ian Ford, J. Wouter Jukema, Chris Power, Elina Hyppönen, Marjo‐Riitta Järvelin, Martin Preisig, Katja Borodulin, Jaakko Kaprio, Mika Kivimäki, Blair H. Smith, Caroline Hayward, Pål Romundstad, Thorkild I. A. Sörensen, Marcus R. Munafò, Naveed Sattar,

Obesity, Physical Activity, Diet

Objectives To investigate, using a Mendelian randomisation approach, whether heavier smoking is associated with a range of regional adiposity phenotypes, in particular those related to abdominal adiposity. Design Mendelian randomisation meta-analyses using a genetic variant (rs16969968/rs1051730 in the CHRNA5-CHRNA3-CHRNB4 gene region) as a proxy for smoking heaviness, of the associations of smoking heaviness with a range of adiposity phenotypes. Participants 148 731 current, former and never-smokers of European ancestry aged ≥16 years from 29 studies in the consortium for Causal Analysis Research in Tobacco and Alcohol (CARTA). Primary outcome measures Waist and hip circumferences, and waist-hip ratio. Results The data included up to 66 809 never-smokers, 43 009 former smokers and 38 913 current daily cigarette smokers. Among current smokers, for each extra minor allele, the geometric mean was lower for waist circumference by −0.40% (95% CI −0.57% to −0.22%), with effects on hip circumference, waist-hip ratio and body mass index (BMI) being −0.31% (95% CI −0.42% to −0.19), −0.08% (−0.19% to 0.03%) and −0.74% (−0.96% to −0.51%), respectively. In contrast, among never-smokers, these effects were higher by 0.23% (0.09% to 0.36%), 0.17% (0.08% to 0.26%), 0.07% (−0.01% to 0.15%) and 0.35% (0.18% to 0.52%), respectively. When adjusting the three central adiposity measures for BMI, the effects among current smokers changed direction and were higher by 0.14% (0.05% to 0.22%) for waist circumference, 0.02% (−0.05% to 0.08%) for hip circumference and 0.10% (0.02% to 0.19%) for waist-hip ratio, for each extra minor allele. Conclusions For a given BMI, a gene variant associated with increased cigarette consumption was associated with increased waist circumference. Smoking in an effort to control weight may lead to accumulation of central adiposity.