FROM JAMA CARDIOLOGY
Obese individuals have shorter life spans and spend significantly more time dealing with the burden of cardiovascular morbidity than do normal-weight individuals, according to a U.S. population-based study.
In a report published online Feb. 28 in JAMA Cardiology , researchers presented an analysis of pooled data from 190,672 participants and 3.2 million person-years of follow-up in 10 prospective cohort studies, including the Framingham Heart Study, the Multi-Ethnic Study of Atherosclerosis, and the Atherosclerosis Risk in Communities Study.
Overweight and obese middle-aged and older adults had a significantly higher cumulative lifetime risk of cardiovascular disease events and cardiovascular death compared with adults with normal body mass index (BMI). The lifetime risk was also higher among young men and women who were obese and morbidly obese – but not those who were overweight – compared with young men and women of normal weight.
Incident cardiovascular events occurred in 37% of overweight middle-aged men and 28% of overweight middle-aged women. In obese middle-aged men and women, those figures were 47% and 39%, respectively, and in the morbidly obese they were 65% and 48%. By comparison, incident cardiovascular events occurred in 32% of middle-aged men of normal BMI, and 22% of women.
Across all the studies, there were 7,136 fatal or nonfatal myocardial infarctions, 3,733 fatal or nonfatal strokes, 4,614 diagnoses of heart failure, and 13,457 cardiovascular disease events during 856,532 person-years of follow-up in middle-aged adults.
After adjustment for age, ethnicity, and smoking status, the competing hazard ratios for experiencing a cardiovascular disease event compared to a noncardiovascular disease death were greater in the higher-BMI categories, and greatest among morbidly obese middle-aged men and women, largely because of a greater proportion of coronary heart disease and heart failure events.
“In addition, greater all-cause mortality in higher-BMI categories occurred at the expense of a greater proportion of deaths from cardiovascular causes in middle-aged men and women who are overweight and obese,” wrote Sadiya S. Khan, MD, MSc, of Northwestern University, Chicago, and her coauthors.
The research suggested that for each increasing unit of BMI in middle-aged men and women, the adjusted competing hazard ratios of incident cardiovascular disease events increased by a significant 5%.
The study found that middle-aged men in the normal and overweight BMI group enjoyed more years free from cardiovascular disease than did obese middle-aged men. In middle-aged women, those who were in the normal BMI range had significantly more years lived free of cardiovascular disease than did overweight or obese women.
The incidence of cardiovascular disease was significantly delayed by an average of 7.5 years in middle-aged men of normal BMI and 7.1 years in middle-aged women of normal BMI, compared with those with morbid obesity.
In terms of longevity, men and women with normal BMI lived on average 5.6 years and 2 years longer, respectively, than did men and women with morbid obesity.
“The results of this study build on prior research from the Cardiovascular Disease Lifetime Risk Pooling Project highlighting marked differences in lifetime risks of CVD and further highlight the importance of consideration of BMI as a risk factor for diminished healthy longevity and greater overall CVD morbidity and mortality,” the authors wrote.
The study was intended to address recent controversy over the health implications of overweight, with some evidence suggesting that overweight individuals have all-cause mortality similar to or lower than that of normal-weight groups.
“While we do observe evidence of the well-described overweight and obesity paradox, in which heavier individuals appear to live longer on average after diagnosis of CVD compared with individuals with normal BMI, our data when following up individuals prior to the onset of CVD indicate that this occurs because of a trend toward earlier onset of disease in individuals who are overweight and obese,” they wrote.
The study did not account for change in BMI over the course of follow-up, nor did it use data on fat distribution or the degree of visceral adiposity, the researchers noted.
“Additional important outcomes of obesity-related morbidity, such as atrial fibrillation, sleep-disordered breathing, and chronic liver disease, were not ascertained routinely in our cohort studies, and we likely underestimated the overall comorbidity burden of excess weight.”
The National Heart, Lung, and Blood Institute supported the study. No conflicts of interest were declared.
SOURCE: Khan SS et al. JAMA Cardiol. 2018 Feb 28. doi: 10.1001/jamacardio.2018.0022 .