Underweight, overweight and obesity as risk factors for mortality and hospitalization
ABSTRACT The prevalence of overweight and obesity is increasing in many countries. We aimed to investigate differences in mortality and severe morbidity between underweight people (body mass index (BMI)<18.5), overweight people (BMI 25 to <30), obese people (BMI> or =30), and those with normal weights (BMI 18.5 to <25).
Random samples of the Swedish population aged 16-74 years in 1980-81 and 1988-89 were followed for 12 years with regard to all-cause mortality and mortality from circulatory diseases, all inpatient care, and inpatient care for circulatory and musculoskeletal diseases. Relative risks (RRs) for different levels of BMI were adjusted for age, longstanding illness, smoking, and educational level at baseline. In addition, analyses were made with delayed entry until the fourth-year after interview.
Obesity and underweight, but not overweight, was associated with higher all-cause mortality. Among underweight men, the adjusted RR for all-cause mortality was 2.4 (95% confidence interval 1.6-3.6), and among underweight women it was 2.0 (1.5-2.7), but population attributable risks (PARs) were small, at 1.2% and 2.7%, respectively. Overweight was associated with increased risks for inpatient care for circulatory diseases, with PARs being 13.4% among men and 8.1% among women, and musculoskeletal diseases (PARs were 12.7% and 12.9%, respectively). Obese men and women had about 50% higher risks of all-cause mortality than normal-weight people, PARs being 3.2% and 3.8% respectively.
This study supports the findings of other studies, in that overweight seems to be an exaggerated risk factor for all-cause mortality, but is related to other chronic disease. Underweight and obesity generally implies greater increases of RRs, but avoidance of overweight may have greater effect on the population level with regard to reduced cardiovascular and locomotor disease.
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ABSTRACT: Obesity is a highly prevalent condition in the US and elsewhere and is associated with increased mortality and morbidity. Here we discuss some issues involved in quantifying the health burden of obesity using population attributable fraction (PAF) estimates and provide examples.Methods We searched PubMed for articles reporting attributable fraction estimates for obesity. We reviewed eligible articles to identify methodological concerns and tabulated illustrative examples of PAF estimates for obesity relative to cancer, diabetes, cardiovascular disease and all-cause mortality.ResultsThere is considerable variability among studies regarding the methods used for PAF calculation and the selection of appropriate counterfactuals. The reported estimates ranged from 5% to 15% for all-cause mortality, -0.2% to 8% for all-cancer incidence, 7% to 44% for cardiovascular disease incidence, and 3% to 83% for diabetes incidence.Conclusions To evaluate a given estimate, it is important to consider whether the exposure and outcome were defined similarly for the PAF and for the relative risks, whether the relative risks were suitable for the population at hand, and whether PAF was calculated using correct methods. Strong causal assumptions are not necessarily warranted. In general PAFs for obesity may be best considered as indicators of association.Annals of Epidemiology 11/2014; 25(3). DOI:10.1016/j.annepidem.2014.11.010 · 2.15 Impact Factor
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ABSTRACT: Remaining controversies on the association between body mass index (BMI) and mortality include the effects of smoking and prevalent disease on the association, whether overweight is associated with higher mortality rates, differences in associations by race and the optimal age at which BMI predicts mortality. To assess the relative risk (RR) of mortality by BMI in Whites and Blacks among subgroups defined by smoking, prevalent disease, and age, 891,572 White and 38,119 Black men and women provided height, weight and other information when enrolled in the Cancer Prevention Study II in 1982. Over 28 years of follow-up, there were 434,400 deaths in Whites and 18,702 deaths in Blacks. Cox proportional-hazards regression was used to estimate multivariable-adjusted relative risks (RR) and 95% confidence intervals (CI). Smoking and prevalent disease status significantly modified the BMI-mortality relationship in Whites and Blacks; higher BMI was most strongly associated with higher risk of mortality among never smokers without prevalent disease. All levels of overweight and obesity were associated with a statistically significantly higher risk of mortality compared to the reference category (BMI 22.5-24.9 kg/m2), except among Black women where risk was elevated but not statistically significant in the lower end of overweight. Although absolute mortality rates were higher in Blacks than Whites within each BMI category, relative risks (RRs) were similar between race groups for both men and women (p-heterogeneity by race = 0.20 for men and 0.23 for women). BMI was most strongly associated with mortality when reported before age 70 years. Results from this study demonstrate for the first time that the BMI-mortality relationship differs for men and women who smoke or have prevalent disease compared to healthy never-smokers. These findings further support recommendations for maintaining a BMI between 20-25 kg/m2 for optimal health and longevity.PLoS ONE 10/2014; 9(10):e109153. DOI:10.1371/journal.pone.0109153 · 3.53 Impact Factor
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ABSTRACT: Background: To estimate and compare prevalence of overweight and obesity among adult people across the 22 districts of Tehran in 2011. Methods: This was a cross-sectional study using data on 47,406 women and 47,525 men aged≥ 15 years from a large population-based survey (Urban HEART-2). Age-standardized prevalence (ASP) of overweight (25≤BMI<30) and obesity (BMI≥30) were estimated for the Tehran's districts. Pear-son Chi2 tests and logistic regression were used to examine any significant differences in prevalence of these disorders across sociodemographic groups. Results: ASPs of overweight were 36.5% and 32.0 % among men and women, respectively (p<0.001). These figures for obesity were 10.7% and 15.3% among men and women, respectively (p<0.001). Crude prevalence of overweight and obesity rose with age up to the age of 54 years and decreased thereafter. Across education groups, the lowest prevalence of overweight/obesity was seen among most educated people. The results showed that being young, single and student were associated with lower odds of overweight/obesity. Conclusion: This study showed a high prevalence of overweight and obesity among adult in Teh-ran. There were significant associations between sociodemographic characteristics and prevalence of overweight/obesity among adults in Tehran. The results of this study might be used in identifying high risk groups of overweight and obesity in Tehran.Medical journal of the Islamic Republic of Iran 01/2015; 29:178.