Association of All-Cause Mortality With Overweight and Obesity Using Standard Body Mass Index Categories

ed items included sample size, number of deaths, age at baseline, length of follow-up, HRs and 95% confidence intervals, sex, age, type of weight and height data (measured or self-reported), country or region, source of study sample, adjustment factors, exclusion and inclusion criteria, and sensitivity analyses. Authors of screened articles were queried for additional information when necessary. In studies that only presented results stratified by smoking or health condition, we selected results for nonsmokers or never smokers or for those without the health condition. We selected the most complex model available for the full sample and used a variety of sensitivity analyses to address issues of possible overadjustment or underadjustment. We categorized HRs into 2 age groupings either as limited solely to people aged 65 years or older or as a mixed-age category (eg, aged 25-64 years or 40-80 years). We classified articles as adequately adjusted, possibly overadjusted, or possibly underadjusted. We categorized HRs by adjustTable 1. Summary Random-Effects Hazard Ratios (HRs) of All-Cause Mortality for Overweight and Obesity Relative to Normal Weight Self-reported or Measured Height and Weight Height and Weight Measured Self-reported No. of HRs Summary HR (95% CI) I , % No. of HRs Summary HR (95% CI) I , % No. of HRs Summary HR (95% CI) I , % BMI of 2530 All ages 140 0.94 (0.91-0.96)a 85.0 89 0.93 (0.89-0.95)a 75.8 51 0.96 (0.92-1.00)a 90.4 Mixed ages 107 0.95 (0.92-0.98)a 86.8 67 0.93 (0.89-0.96)a 79.6 40 0.98 (0.93-1.03)a 90.7 Age 65 y only 33 0.90 (0.86-0.94)a 51.2 22 0.90 (0.84-0.95) 31.2 11 0.90 (0.84-0.96)a 71.0 BMI of 30 All ages 84 1.18 (1.12-1.25)a 86.7 56 1.13 (1.06-1.19)a 73.4 28 1.29 (1.18-1.41)a 89.7 Mixed ages 63 1.23 (1.16-1.31)a 87.2 41 1.16 (1.10-1.24)a 74.6 22 1.36 (1.25-1.48)a 86.1 Age 65 y only 21 1.03 (0.94-1.12)a 61.5 15 0.98 (0.86-1.12)a 61.1 6 1.09 (0.96-1.23)a 67.0 BMI of 3035 All ages 53 0.95 (0.88-1.01)a 86.8 30 0.94 (0.86-1.03)a 80.5 23 0.95 (0.85-1.06)a 90.1 Mixed ages 42 0.96 (0.89-1.04)a 87.7 24 0.95 (0.86-1.06)a 83.2 18 0.97 (0.87-1.09)a 90.0 Age 65 y only 11 0.87 (0.72-1.05)a 76.3 6 0.89 (0.71-1.11) 56.2 5 0.83 (0.58-1.20)a 85.7 BMI of 35 All ages 53 1.29 (1.18-1.41)a 81.7 30 1.25 (1.13-1.39)a 65.4 23 1.34 (1.16-1.55)a 88.3 Mixed ages 42 1.32 (1.19-1.45)a 82.8 24 1.28 (1.14-1.44)a 68.9 18 1.35 (1.16-1.58)a 89.0 Age 65 only 11 1.20 (0.94-1.52)a 70.6 6 1.10 (0.89-1.34) 25.1 5 1.29 (0.77-2.17)a 85.2 Abbreviation: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared). a Indicates significant heterogeneity (P .05). ASSOCIATION OF ALL-CAUSE MORTALITY WITH OVERWEIGHT AND OBESITY 72 JAMA, January 2, 2013—Vol 309, No. 1 ©2013 American Medical Association. All rights reserved. Downloaded From: http://jama.jamanetwork. com/pdfaccess.ashx? url=/data/journals/jama/926163/ on 04/06/2017 ment level, by whether the data were measured or self-reported, by whether the analysis was performed separately for men and women or for both sexes combined, and by region (North America, Europe, and other). We used a random-effects model to summarize the results overall and within subgroups and based statistically significant heterogeneity on a P value of less than . 05. We calculated the quantity I to describe the degree of heterogeneity with values of 25%, 50%, and 75% considered low, moderate, and high, respectively. We also used a sequential approach similar to that described by Patsopoulos et al to assess consistency of findings when heterogeneity was reduced. All analyses were performed with SAS version 9.3 (SAS Institute Inc). For sensitivity analyses, we examined the effects on HRs of incorporating results from a recent large pooled study for overweight. For comparative purposes, we also constructed approximate HRs relative to normal weight from several recent large studies that had used finer BMI groupings and thus did not meet our inclusion criteria. To do this, we averaged HRs from the finer BMI groupings over groups corresponding to the standard BMI categories, weighting the HRs by the number of deaths.