What is the clinical evidence from this study?

Study design: Cohort. Population: Coronary heart disease (n=88393). Intervention: Obesity and physical inactivity vs. Healthy weight and physically active. Primary outcome: Incident major CHD events (including nonfatal myocardial infarction and fatal CHD) (RR 3.44, 95% CI 2.81 to 4.21).

January 31, 2006Open Access

Obesity as Compared With Physical Activity in Predicting Risk of Coronary Heart Disease in Women

Key Result

Obesity and physical inactivity were associated with a significantly higher risk of incident major CHD events compared to being healthy weight and active (RR 3.44; 95% CI 2.81-4.21).

Study Design

Type

Cohort (n=88,393)

Structured PICO

Do obesity and physical inactivity independently increase the risk of incident major CHD events in women without baseline cardiovascular disease?

Population

88,393 women, 34 to 59 years of age, in the Nurses' Health Study without cardiovascular disease and cancer at baseline.

Intervention

Obesity (BMI ≥30 kg/m2) and physical inactivity (exercise <1 h/wk)

Comparator

Healthy weight (BMI 18.5 to 24.9 kg/m2) and physically active (exercise ≥3.5 h/wk)

Outcome

Incident major CHD events (including nonfatal myocardial infarction and fatal CHD)hard clinical

Obesity and physical inactivity independently contribute to the development of CHD in women, underscoring the importance of both maintaining a healthy weight and regular physical activity.

Main Result

Effect estimate: RR 3.44 (95% CI 2.81 to 4.21)

Abstract

BACKGROUND: The comparative importance of physical inactivity and obesity as predictors of coronary heart disease (CHD) risk remains unsettled. METHODS AND RESULTS: We followed 88 393 women, 34 to 59 years of age, in the Nurses' Health Study from 1980 to 2000. These participants did not have cardiovascular disease and cancer at baseline. We documented 2358 incident major CHD events (including nonfatal myocardial infarction and fatal CHD) during 20 years of follow-up, including 889 cases of fatal CHD and 1469 cases of nonfatal myocardial infarction. In a multivariate model adjusting for cardiovascular risk factors, overweight and obesity were significantly associated with increased risk of CHD, whereas increasing levels of physical activity were associated with a graded reduction in CHD risk (P or =3.5 h/wk) as the reference group, the relative risks of CHD were 3.44 (95% confidence interval CI, 2.81 to 4.21) for women who were obese (BMI > or =30 kg/m2) and sedentary (exercise <1 h/wk), 2.48 (95% CI, 1.84 to 3.34) for women who were active but obese, and 1.48 (95% CI, 1.24 to 1.77) for women who had a healthy weight but were sedentary. In combined analyses of waist-hip ratio and physical activity, both waist-hip ratio and physical activity were significant predictors of CHD, and the highest risk was among women in the lowest category of physical activity and the highest tertile of waist-hip ratio (relative risk=3.03; 95% CI, 1.96 to 4.18). Even a modest weight gain (4 to 10 kg) during adulthood was associated with 27% (95% CI, 12% to 45%) increased risk of CHD compared with women with a stable weight after adjusting for physical activity and other cardiovascular risk factors. CONCLUSIONS: Obesity and physical inactivity independently contribute to the development of CHD in women. These data underscore the importance of both maintaining a healthy weight and regular physical activity in preventing CHD.