Cause-specific excess deaths associated with underweight, overweight, and obesity

JAMA. 2007 Nov 7;298(17):2028-37. doi: 10.1001/jama.298.17.2028.

Abstract

Context: The association of body mass index (BMI) with cause-specific mortality has not been reported for the US population.

Objective: To estimate cause-specific excess deaths associated with underweight (BMI <18.5), overweight (BMI 25-<30), and obesity (BMI > or =30).

Design, setting, and participants: Cause-specific relative risks of mortality from the National Health and Nutrition Examination Survey (NHANES) I, 1971-1975; II, 1976-1980; and III, 1988-1994, with mortality follow-up through 2000 (571,042 person-years of follow-up) were combined with data on BMI and other covariates from NHANES 1999-2002 with underlying cause of death information for 2.3 million adults 25 years and older from 2004 vital statistics data for the United States.

Main outcome measures: Cause-specific excess deaths in 2004 by BMI levels for categories of cardiovascular disease (CVD), cancer, and all other causes (noncancer, non-CVD causes).

Results: Based on total follow-up, underweight was associated with significantly increased mortality from noncancer, non-CVD causes (23,455 excess deaths; 95% confidence interval [CI], 11,848 to 35,061) but not associated with cancer or CVD mortality. Overweight was associated with significantly decreased mortality from noncancer, non-CVD causes (-69 299 excess deaths; 95% CI, -100 702 to -37 897) but not associated with cancer or CVD mortality. Obesity was associated with significantly increased CVD mortality (112,159 excess deaths; 95% CI, 87,842 to 136,476) but not associated with cancer mortality or with noncancer, non-CVD mortality. In further analyses, overweight and obesity combined were associated with increased mortality from diabetes and kidney disease (61 248 excess deaths; 95% CI, 49 685 to 72,811) and decreased mortality from other noncancer, non-CVD causes (-105,572 excess deaths; 95% CI, -161 816 to -49,328). Obesity was associated with increased mortality from cancers considered obesity-related (13,839 excess deaths; 95% CI, 1920 to 25,758) but not associated with mortality from other cancers. Comparisons across surveys suggested a decrease in the association of obesity with CVD mortality over time.

Conclusions: The BMI-mortality association varies by cause of death. These results help to clarify the associations of BMI with all-cause mortality.

MeSH terms

  • Adult
  • Aged
  • Body Mass Index*
  • Cardiovascular Diseases / mortality
  • Cause of Death*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neoplasms / mortality
  • Nutrition Surveys
  • Obesity / epidemiology*
  • Overweight*
  • Proportional Hazards Models
  • Risk
  • Thinness / epidemiology*
  • United States / epidemiology