September 8, 2011 — Overweight and obesity, and large waist circumference without obesity, are associated with increased all-cause mortality risk in black women who had never smoked, according to the results of aprospective study reported in the September 8 issue of the New England Journal of Medicine.
"Recent pooled analyses show an increased risk of death with increasing levels of the body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) of 25.0 or higher in populations of European ancestry, a weaker association among East Asians, and no association of an increased BMI with an increased risk of death among South Asians," write Deborah A. Boggs, ScD, from the Slone Epidemiology Center at Boston University in Boston, Massachusetts, and colleagues. "The limited data available on blacks indicate that the risk of death is increased only at very high levels of BMI (≥35.0)."
Using follow-up data from 1995 through 2008 in the Black Women's Health Study, the investigators prospectively examined the association of BMI and waist circumference with mortality risk among 51,695 black women who were 21 to 69 years old at study enrollment, and who had no history of cancer or cardiovascular disease. Multivariable proportional-hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).
During follow-up, 1773 women died, including 770 of 33,916 women who had never smoked. Mortality risk among nonsmokers was lowest for a BMI of 20.0 to 24.9 kg/m2 and rose as the BMI increased above this range. When a BMI of 22.5 to 24.9 kg/m2 was used as a reference category, the HR was 1.12 (95% CI, 0.87 - 1.44) for a BMI of 25.0 to 27.4 kg/m2, 1.31 (95% CI, 1.01 - 1.72) for a BMI of 27.5 to 29.9 kg/m2, 1.27 (95% CI, 0.99 - 1.64) for a BMI of 30.0 to 34.9 kg/m2, 1.51 (95% CI, 1.13 - 2.02) for a BMI of 35.0 to 39.9 kg/m2, and 2.19 (95% CI, 1.62 - 2.95) for a BMI of 40.0 to 49.9 kg/m2 (P < .001 for trend).
Among women with a BMI of less than 30.0 kg/m2, a large waist circumference was associated with greater risk for all-cause mortality.
"The risk of death from any cause among black women increased with an increasing BMI of 25.0 or higher, which is similar to the pattern observed among whites," the study authors write. "Waist circumference appeared to be associated with an increased risk of death only among nonobese women."
Limitations of this study include use of self-reported measures of body size and unknown generalizability to men.
"For both BMI and waist circumference, the positive association with the risk of death was stronger for deaths from cardiovascular disease than for deaths from cancer or other causes," the study authors conclude. "Weaker associations were observed among current and former smokers than among women who had never smoked, even after adjustment for pack-years of smoking."
The National Cancer Institute supported this study. Disclosure forms provided by the authors are available with the full text of the original article.
N Engl J Med. 2011;365:901-908.
0 comments:
Post a Comment