Weight and mortality.

Weight and Mortality To the Editor: In a recent article, Dr Hu states1 that the findings regarding weight and mortality in Flegal et al2 are “most likely” the result of “methodologic flaws,” namely the failure to exclude subjects on the basis of smoking and preexisting illness. In August 2005, we replied3 to a similar assertion by Willett, Hu, and colleagues.4 In that reply we stated, “To determine if reverse causation might be affecting our results, we performed extensive supplemental analyses of our data, stratifying by baseline health status and using multiple simultaneous exclusions for smoking, early deaths, and involuntary weight loss. The relative risks were little affected by such exclusions, and changes were often in the direction opposite to those anticipated by Willett et al.”3 Reference 2 in our reply provided the hyperlink to these supplemental analyses: http://www.cdc.gov/nchs/products/ pubs/pubd/hestats/ excess_deaths/excess_deaths.htm. Exclusions based on health status, smoking, early deaths, and involuntary weight loss eliminated 80% to 90% of the deaths and made the estimates of relative risks less precise, as has also been seen in other published analyses.5 However, our estimates of excess deaths depend on the point estimates of relative risks, not on their variance (which is taken into account in our standard error calculations). Our supplemental analyses provided no indication that residual confounding by smoking or by preexisting illness biased our results or that our findings on weight and mortality were due to “methodologic flaws.” We encourage interested readers to review these supplemental analyses, which answer the criticisms mentioned by Dr. Hu1 and greatly expand on the sensitivity analyses.2