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Etiology

Weight loss and weight fluctuation were associated with death in men with pre-existing disease and men who smoked

ACP J Club. 1996 Mar-April;124:49. doi:10.7326/ACPJC-1996-124-2-049


Source Citation

Iribarren C, Sharp DS, Burchfiel CM, Petrovitch H. Association of weight loss and weight fluctuation with mortality among Japanese American men. N Engl J Med. 1995 Sep 14;333:686-92.


Abstract

Objective

To determine the association between weight loss and weight fluctuation and increased risk for all-cause mortality and death from cardiovascular causes.

Design

16-year cohort analytic study of Japanese-American men in the Honolulu Heart Program.

Setting

Community-based study in Hawaii.

Participants

Japanese-American men aged 45 to 68 years living on Oahu were enrolled in the Honolulu Heart Program in 1965. 6537 men (mean age 54 y) who had 3 physical examinations between 1965 and 1974 were followed from 1973 to 1988; mortality was documented by hospital surveillance, state health department records, and newspaper obituaries.

Assessment of Risk Factors

Data collected at each examination included socioeconomic characteristics, medical history, anthropometric measures, smoking status, alcohol consumption, physical activity, and blood chemistry. Weight change was categorized into 5 groups that ranged from weight loss > 4.5 kg to weight gain > 4.5 kg. The reference group was the middle group (-2.5 to +2.4 kg). Weight fluctuation was represented by variation from the overall time trend of weight.

Main Outcome Measures

Relative risk (RR) for all-cause mortality and death from cardiovascular causes (coronary heart disease and circulatory problems), cancer, and noncardiovascular and noncancerous causes.

Main Results

1217 men died in the 16-year period: 355 of cardiovascular causes, 480 of cancer, and 382 of noncardiovascular and noncancerous causes. After adjustment for confounding factors, a weight loss > 4.5 kg was associated with death from noncardiovascular and noncancerous causes (RR 1.45, 95% CI 1.08 to 1.94) and from all causes (RR 1.21, CI 1.02 to 1.43), and a weight loss from 2.6 to 4.5 kg was associated with death from other circulatory problems (RR 1.52, CI 1.00 to 2.29), noncardiovascular and noncancerous causes (RR 1.50, CI 1.14 to 1.97), and all causes (RR 1.29, CI 1.10 to 1.51). Weight gain was not associated with any cause of death. Men who gained 2.5 to 4.5 kg had the lowest risk for death (RR for death from all causes 0.83, CI 0.66 to 1.02). Men with the greatest fluctuation in weight had increased risk for death from noncardiovascular and noncancerous causes (RR 1.53, CI 1.12 to 2.10), cardiovascular causes (RR 1.41, CI 1.03 to 1.93), and all causes (RR 1.25, CI 1.05 to 1.48). Weight loss and weight fluctuation were associated with death only in men who had pre-existing disease or men who were current smokers.

Conclusion

Weight loss and weight fluctuation were associated with death in men with pre-existing disease and men who smoked.

Source of funding: National Heart, Lung, and Blood Institute.

For article reprint: Dr. C. Iribarren, Division of Epidemiology, School of Public Health, University of Minnesota, 1300 South Second Street, Suite 300, Minneapolis, MN 55454-1015, USA. FAX 612-624-0315.


Commentary

Increased body mass index predicted mortality in women

The prevalence of obesity is increasing in industrialized Western societies. According to 1988 to 1991 national health statistics (1), a third of all adults in the United States were at least 20% above their ideal weight. This is a striking increase from the stable, 25% prevalence of overweight documented between 1960 and 1981. Although the health hazards of excess weight have been documented (2), the relation between obesity and morbidity is not as well understood as many other risk factor-morbidity relations. These reports from the Honolulu Heart Program and Nurses' Health Study provide no startling new information, but they do advance our understanding of obesity and its risks.

One source of confusion in the body mass-mortality relation is the J-shaped curve issue; that is, the observation in some studies that increased mortality is found at both the low and high ends of the body weight spectrum. The reports from both the Nurses' Health Study and the Honolulu Heart Program Study showed the importance of smoking and preexisting illness as confounders in the body mass-mortality curve. When smoking and preexisting diseases were considered, minimal or no evidence of increased mortality in underweight persons was observed.

With regard to the strength of the body mass-mortality relation, the population samples from both studies showed a modest but significant increased risk for overall mortality when the most overweight subgroups were compared with the lowest-risk subgroups. In 1990, the Nurses' Health Study published its 8-year follow-up data on overweight as a major health risk for coronary artery disease in women (3). The current 16-year mortality data are even more striking because nonsmoking women with a BMI ≥ 29.0 (> 30% above ideal weight) showed a 5-fold increase in mortality from coronary heart disease compared with women with a BMI < 22.0. Although this increase was partly related to the high prevalence of hypertension, dyslipidemia, and diabetes mellitus among overweight persons, significant excess risk persisted even after controlling for these variables. The cause of this "specific" obesity-related cardiovascular risk is not clearly understood.

The current Nurses' Health Study report also analyzed cardiac mortality on the basis of self-measured waist-to-hip circumferences. The importance of body fat distribution as a predictor for coronary death was shown by the RR of almost 9.0 for nonsmoking women in the highest quintile for waist-to-hip ratio. This association was somewhat stronger than that between BMI and cardiovascular deaths.

Byers (4) previously noted the difficulty of interpreting the mortality findings in these studies as they relate to weight change and weight fluctuation. Data on changes in weight were collected and analyzed differently, and the sex, ethnic background, and weight distributions of the participants were very different in the 2 studies. Perhaps the most consistent finding came from the large population of the Nurses' Health Study, which showed an increase in all causes of mortality with a >10-kg weight gain after age 18 years.

The limitations of these well-designed, long-term cohort studies were well described by the authors, and the conclusions were reasonable extensions of the data. The findings should allay concern about any adverse effects of low body weight in otherwise healthy persons and should reinforce concern about increased mortality, particularly cardiovascular, in overweight persons.

Paul D. Levinson, MD
Brown University School of MedicineProvidence, Rhode Island, USA


References

1. Kuczmarski RJ, Flegal KM, Campbell SM, Johnson CL. Increasing prevalence of overweight among United States adults: the National Health and Nutrition Examination Surveys, 1960-1991. JAMA. 1994;272: 205-11.

2. Pi-Sunyer FX. Medical hazards of obesity. Ann Intern Med. 1993;119:655-60.

3. Manson JE, Colditz GA, Stampfer MJ, et al. A prospective study of obesity and risk of coronary heart disease in women. N Engl J Med. 1990;322:882-9.

4. Byers T. Body weight and mortality. N Engl J Med. 1995;333:723-4.