Tuesday, March 12, 2013

Weight gain after quitting smoking does not negate health benefits

Mass. General-led study finds that quitting cuts the risk of cardiovascular events in half, despite any weight gain

An analysis of data from the Framingham Offspring Study – a long-term study that follows children of participants in the original Framingham Heart Study – may have answered a question that has troubled individuals considering stopping smoking:  do the health effects of any weight gained after quitting outweigh the known cardiovascular benefits of smoking cessation?  The report in the March 13 issue of JAMA concludes that the benefits of stopping smoking far exceed any weight-gain associated risk.

"Among people without diabetes, those who stopped smoking had a 50 percent reduction in the risk for heart attack, stroke or cardiovascular death, and accounting for any weight increase didn't change that risk reduction," says James Meigs, MD, MPH, of the General Medicine Unit at Massachusetts General Hospital (MGH) senior author of the JAMA report.  "In patients with diabetes – among whom weight gain is a particular concern – we saw the same pattern of a large risk reduction regardless of weight gained."

No study has previously investigated whether smoking-cessation-associated weight gain increases the risk of cardiovascular disease.  One did look at the effects on risk factors such as blood pressure and lipid levels, but none have analyzed the actual occurrence of cardiovascular events.  Participants in the Framingham Offspring Study, which began in 1971, have a comprehensive medical exam and history taken every four to six years.  The current investigation analyzed data from participant visits conducted from the mid 1980s into the mid-2000s, which covering the third to eighth visits for the overall study.  The number of participants at each exam cycle ranged from almost 2,400 to about 3,250, totaling 11,148 individual person-exams.

Based on information gathered at each exam, participants were categorized as never smokers, current smokers, recent quitters – who had stopped smoking since their last exam – and long-term quitters.  At the third study visit, 31 percent of participants were current smokers, and by the eighth visit only 13 percent continued to smoke.  A general trend toward weight gain was seen across all study participants.  Smokers, never smokers, and long-term quitters gained an average of 1 to 2 pounds between study visits, while recent quitters had gained an average of 5 to 10 pounds since their previous visit.  But no matter how much weight they gained, the risk of cardiovascular events in the six years after quitting dropped in half for participants without diabetes.  A similar drop in the incidence of cardiovascular events was seen in participants with diabetes, but it did not reach statistical significance, probably because less than 15 percent of the overall group was know to have diabetes.  

"We now can say without question that stopping smoking has a very positive effect on cardiovascular risk for patients with and without diabetes, even if they experience the moderate weight gain seen in this study, which matches post-cessation weight increase reported in other studies," says Meigs, an associate professor of Medicine at Harvard Medical School.

Lead author of the JAMA report is Carole Clair, MD, MSc, now at the University of Lausanne, Switzerland.  Additional co-authors are Nancy Rigotti, MD, of the MGH Tobacco Research and Treatment Center; Bianca Porneala, MS, MGH Medicine; Caroline Fox, MD, MPH, Framingham Heart Study; and Ralph D'Agostino, PhD, and Michale Pencina, PhD, Boston University.  Support for the study includes Swiss National Science Foundation grant PBLAP3127728/1, National Heart, Lung and Blood Institute (NHLBI) grant 5K24HL4440-10, National Institute of Diabetes and Digestive and Kidney Disease grant K24 DK080140 and a grant from the SICPA Foundation of Switzerland.  The Framingham Heart Study is supported by the NHLBI.  

Massachusetts General Hospital (www.massgeneral.org), founded in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of more than $775 million and major research centers in AIDS, cardiovascular research, cancer, computational and integrative biology, cutaneous biology, human genetics, medical imaging, neurodegenerative disorders, regenerative medicine, reproductive biology, systems biology, transplantation biology and photomedicine. In July 2012, MGH moved into the number one spot on the 2012-13 U.S. News & World Report list of "America's Best Hospitals."

Ryan Donovan, 617 724-6433, rcdonovan@partners.org

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