Relation of body fat categories by Gallagher classification and by continuous variables to mortality in patients with coronary heart disease

Abstract

Although obesity is a coronary heart disease risk factor, in cohorts of patients with coronary heart disease, an "obesity paradox" exists whereby patients with obesity have a better prognosis than do leaner patients. Obesity is generally defined by body mass index, with relatively little described regarding body fat (BF). In this study, 581 consecutive patients with coronary heart disease divided into the Gallagher BF categories of underweight (n = 12), normal (n = 189), overweight (n = 214), and obese (n = 166) were evaluated, and 3-year mortality was assessed using the National Death Index. Mortality was U shaped, being highest in the underweight group (25%, p <0.0001 vs all groups) and lowest in the overweight group (2.3%), with intermediate mortality in the normal-BF (6.4%, p = 0.02 vs overweight) and obese (3.6%) groups. In multiple regression analysis, high BF (odds ratio 0.89, 95% confidence interval 0.82 to 0.95) and higher Gallagher class (odds ratio 0.46, 95% confidence interval 0.25 to 0.84) were independent predictors of lower mortality. In conclusion, on the basis of Gallagher BF, an obesity paradox exists, with the highest mortality in the underweight and normal-BF groups and the lowest mortality in the overweight group. Lower BF as a continuous variable and by Gallagher classification as a categorical value were independent predictors of higher mortality.