Abstract
IMPORTANCE: Prior studies have demonstrated lower all-cause mortality in individuals who are overweight compared with those with normal body mass index (BMI), but whether this may come at the cost of greater burden of cardiovascular disease (CVD) is unknown. OBJECTIVE: To calculate lifetime risk estimates of incident CVD and subtypes of CVD and to estimate years lived with and without CVD by weight status. DESIGN, SETTING, AND PARTICIPANTS: In this population-based study, we used pooled individual-level data from adults (baseline age, 20-39, 40-59, and 60-79 years) across 10 large US prospective cohorts, with 3.2 million person-years of follow-up from 1964 to 2015. All participants were free of clinical CVD at baseline with available BMI index and CVD outcomes data. Data were analyzed from October 2016 to July 2017. EXPOSURES: World Health Organization-standardized BMI categories. MAIN OUTCOMES AND MEASURES: Total CVD and CVD subtype, including fatal and nonfatal coronary heart disease, stroke, congestive heart failure, and other CVD deaths. Heights and weights were measured directly by investigators in each study, and BMI was calculated as weight in kilograms divided by height in meters squared. We performed (1) modified Kaplan-Meier analysis to estimate lifetime risks, (2) adjusted competing Cox models to estimate joint cumulative risks for CVD or noncardiovascular death, and (3) the Irwin restricted mean to estimate years lived free of and with CVD. RESULTS: Of the 190 672 in-person examinations included in this study, the mean (SD) age was 46.0 (15.0) years for men and 58.7 (12.9) years for women, and 140 835 patients (73.9%) were female. Compared with individuals with a normal BMI (defined as a BMI of 18.5 to 24.9), lifetime risks for incident CVD were higher in middle-aged adults in the overweight and obese groups. Compared with normal weight, among middle-aged men and women, competing hazard ratios for incident CVD were 1.21 (95% CI, 1.14-1.28) and 1.32 (95% CI, 1.24-1.40), respectively, for overweight (BMI, 25.0-29.9), 1.67 (95% CI, 1.55-1.79) and 1.85 (95% CI, 1.72-1.99) for obesity (BMI, 30.0-39.9), and 3.14 (95% CI, 2.48-3.97) and 2.53 (95% CI, 2.20-2.91) for morbid obesity (BMI, ≥40.0). Higher BMI had the strongest association with incident heart failure among CVD subtypes. Average years lived with CVD were longer for middle-aged adults in the overweight and obese groups compared with adults in the normal BMI group. Similar patterns were observed in younger and older adults. CONCLUSIONS AND RELEVANCE: In this study, obesity was associated with shorter longevity and significantly increased risk of cardiovascular morbidity and mortality compared with normal BMI. Despite similar longevity compared with normal BMI, overweight was associated with significantly increased risk of developing CVD at an earlier age, resulting in a greater proportion of life lived with CVD morbidity.
Generated Summary
This study, published in JAMA Cardiology, investigated the association between Body Mass Index (BMI) and the lifetime risk of cardiovascular disease (CVD) and its subtypes. The research utilized pooled individual-level data from 10 large US prospective cohorts. The study included adults aged 20-79, with 3.2 million person-years of follow-up from 1964 to 2015. The primary objective was to calculate lifetime risk estimates of incident CVD and its subtypes based on different weight statuses and to estimate years lived with and without CVD. Data analysis was conducted from October 2016 to July 2017, using World Health Organization-standardized BMI categories. The researchers employed modified Kaplan-Meier analysis and adjusted competing Cox models to estimate risks and years lived with and without CVD.
Key Findings & Statistics
- The study included 190,672 in-person examinations.
- The mean age of participants was 46.0 (SD 15.0) years for men and 58.7 (SD 12.9) years for women.
- 140,835 (73.9%) participants were female.
- Compared to individuals with a normal BMI (18.5 to 24.9), the lifetime risks for incident CVD were higher in middle-aged adults in the overweight and obese groups.
- Among middle-aged men, the competing hazard ratios for incident CVD were:
- 1.21 (95% CI, 1.14-1.28) for overweight (BMI 25.0-29.9)
- 1.67 (95% CI, 1.55-1.79) for obesity (BMI 30.0-39.9)
- 3.14 (95% CI, 2.48-3.97) for morbid obesity (BMI, ≥40.0)
- Among middle-aged women, the competing hazard ratios for incident CVD were:
- 1.32 (95% CI, 1.24-1.40) for overweight (BMI 25.0-29.9)
- 1.85 (95% CI, 1.72-1.99) for obesity (BMI 30.0-39.9)
- 2.53 (95% CI, 2.20-2.91) for morbid obesity (BMI, ≥40.0)
- Higher BMI was most strongly associated with incident heart failure among CVD subtypes.
- Average years lived with CVD were longer for middle-aged adults in the overweight and obese groups compared to normal BMI adults.
Other Important Findings
- The study found that higher BMI was strongly associated with an increased risk of incident CVD, particularly among middle-aged adults.
- The association between BMI and CVD risk was consistent across different CVD subtypes, including coronary heart disease, stroke, and heart failure.
- Overweight and obesity were associated with a greater proportion of life lived with CVD morbidity.
- Similar patterns were observed in younger and older adults.
Limitations Noted in the Document
- The study’s reliance on observational data introduces the potential for unmeasured confounding factors that could influence the observed associations.
- The study population comprised individuals from large US cohorts, potentially limiting the generalizability of the findings to other populations.
- The study used BMI as a measure of adiposity, which may not fully capture the complexities of body composition and fat distribution.
- The study did not account for potential changes in BMI over time, which could affect the accuracy of lifetime risk estimates.
- The study’s findings are based on data up to 2015, and changes in CVD risk factors and treatments since then might affect the applicability of the results.
Conclusion
The study’s findings underscore the significant impact of BMI on cardiovascular health, with obesity associated with shorter longevity and an increased risk of cardiovascular morbidity and mortality. Overweight individuals, while potentially experiencing similar longevity compared to those with normal BMI, face an increased risk of developing CVD earlier in life, leading to a greater proportion of life lived with CVD morbidity. This study reinforces the importance of maintaining a healthy weight to mitigate the risk of CVD and improve overall health outcomes. The results suggest the need for public health interventions to address the rising rates of overweight and obesity, particularly among middle-aged adults. Clinicians and policymakers should prioritize strategies that promote healthy lifestyles, including balanced diets and regular physical activity, to reduce the burden of CVD. Further research is needed to explore the underlying mechanisms linking BMI to CVD risk and to evaluate the effectiveness of interventions aimed at weight management and CVD prevention. The study highlights the complex relationship between weight, longevity, and cardiovascular health. While it provides valuable insights into the long-term consequences of different BMI categories, it also underscores the importance of considering other factors that influence cardiovascular risk. The study’s findings emphasize the need for a comprehensive approach to CVD prevention that addresses multiple risk factors and promotes overall well-being. In conclusion, this study offers crucial insights into the long-term health implications of weight status and the pressing need for effective strategies to curb the rising prevalence of obesity and its impact on cardiovascular health. The study contributes to the growing body of evidence supporting the importance of maintaining a healthy weight to optimize longevity and minimize the burden of CVD.
IFFS Team Summary
- 10 Cohort studies in USA, over decades, 140 800 individuals and 3.2 million person-years of follow up
- Obesity associated with shorter longevity and significantly increased risk of cardiovascular morbidity and mortality compared with normal BMI.
- Overweight BMI associated with significantly increased risk of developing CVD at an earlier age, resulting in a greater proportion of life lived with CVD morbidity, though similar lifespan