Abstract 5086: Low Cardiorespiratory Fitness Fails to Predict Mortality in Severe (Class II or Greater) Obesity
Obesity is associated with reduced functional aerobic capacity (FAC). Even though low FAC strongly predicts mortality in normal weight persons; the relationship between FAC and mortality in obese persons is unclear. 5328 non-smoking men (average age, 51.8 ± 11.5years) without baseline cardiovascular disease referred for treadmill exercise testing during 1986 –1991 were classified by body mass index (BMI) into normal weight (BMI 18.5–24.9kg/m2), overweight (BMI 25.0 –29.9kg/m2), obese (BMI 30.0 –34.9 kg/m2) and severely obese (BMI ≥ 35.0) kg/m2 categories. FAC was assessed by maximal exercise test and based on age and gender specific metabolic equivalents (METS). Patients were divided into low fitness (FAC<73% of predicted METs or lowest quintile for cohort) and normal fitness (FAC ≥73% of predicted METs) groups. Cox proportional hazards analysis was used to determine the relationship of all-cause mortality to fitness in each BMI category. There were 189 deaths during an average 16.4 ± 2.6 years of follow-up. 14-year mortality rates by BMI and fitness categories and age-adjusted hazards ratio comparing low with normal fitness are presented in Table⇓. In normal weight, overweight and obese patients, low FAC was significantly associated with mortality (p<0.05). However, in severely obese patients low FAC was not associated with mortality (p=0.97). Low FAC, as determined during treadmill exercise testing, does not predict mortality in severely obese patients. Estimation of cardiorespiratory fitness by direct measurement of oxygen consumption may be required in such patients.