Body Mass, Fitness and Survival in Veteran Patients: Another Obesity Paradox?

Abstract 

Purpose

The paradox of obesity in patients with heart failure (HF) also has been observed in non-HF veteran patients. Veterans had to have met military fitness requirements at the time of their enlistment. Therefore, we assessed the relation of body mass index (BMI) to mortality in a clinical cohort of non-HF veterans, adjusting for fitness.

Methods

After excluding HF patients (n=580), the study population comprised 6876 consecutive patients (mean age 58 [±11] years) referred for exercise testing. Patients were classified by BMI category: normal weight (BMI 18.5-24.9 kg/m²), overweight (BMI 25.0-29.9 kg/m²), or obese (BMI ≥30.0 kg/m²). The association between BMI, fitness, other clinical variables, and all-cause mortality was assessed by Cox proportional hazards analysis.

Results

During a mean (±SD) follow-up of 7.5±4.5 years, a total of 1571 (23%) patients died. In a multivariate analysis including clinical, risk factor, and exercise test data, higher BMI was associated with better survival. Expressing the data by BMI category, obese patients were 22% less likely to die (relative risk [RR]=0.78, 95% confidence interval [CI], 0.69-0.90, P<.001) than patients of normal weight. After further adjustment for cardiorespiratory fitness (CRF), this relationship strengthened such that mortality risk for the obese category was 35% lower (RR=0.65, 95% CI, 0.57-0.76, P<.001), versus the normal weight category.

Conclusions

As has been observed in HF patients, obesity was associated with a substantially lower mortality risk in a clinical population of non-HF veterans. Higher CRF and obesity in later life may account for an obesity paradox in this population.

Keywords: Cardiorespiratory fitness, Exercise testing, Mortality, Obesity