title: Use of functional aerobic capacity based on stress testing to predict outcomes in normal, overweight, and obese patients.
abstract: OBJECTIVE
  To determine the poorly studied relationship between functional aerobic capacity (FAC) as measured by treadmill stress testing and mortality in normal, overweight, and obese patients.
  
  
  METHODS
  Patients were identified retrospectively from the stress testing database at Mayo Clinic in Rochester, Minnesota. We selected 5328 male nonsmokers (mean ± SD age, 51.8±11.5 years) without baseline cardiovascular disease who were referred for treadmill exercise testing between January 1, 1986, and December 31, 1991, and classified them by body mass index (BMI) into normal-weight (18.5-24.9 kg/m(2)), overweight (25.0-29.9 kg/m(2)), and obese (≥30 kg/m(2)) categories. Functional aerobic capacity was assessed by maximal exercise test results based on age- and sex-specific metabolic equivalents, and patients were stratified into fitness quintiles. Cox proportional hazards analysis was used to determine the relationship of all-cause mortality to fitness in each BMI category.
  
  
  RESULTS
  There were 322 deaths during 14 years of follow-up. After adjustment for age and exercise confounders, FAC predicted mortality in the 3 BMI groups. Hazard ratios for FAC less than 80% of predicted vs a reference group with normal BMI and fitness (FAC ≥100%) were 1.754 (95% CI, 0.874-3.522), 1.962 (1.356-2.837), and 1.518 (1.056-2.182) for the normal, overweight, and obese groups, respectively. The CIs of the hazard ratios overlapped with no statistically significant differences (P>.05).
  
  
  CONCLUSIONS
  A significant increase in mortality occurs with FAC below 80% of predicted for overweight and obese subjects and below 70% for normal weight subjects. Our results suggest that clinicians need not adjust the standard for low fitness in obese patients.
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, AZ.
authors.forename: Muaz
authors.initials: M
authors.lastname: Abudiab
authors.forename: Bilal
authors.initials: B
authors.lastname: Aijaz
authors.forename: Tomas
authors.initials: T
authors.lastname: Konecny
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Kopecky
authors.forename: Ray W
authors.initials: RW
authors.lastname: Squires
authors.forename: Randal J
authors.initials: RJ
authors.lastname: Thomas
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Allison
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000150:complications / Q000401:mortality / Q000503:physiopathology; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D055686:Metabolic Equivalent; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D009765:Obesity / Q000150:complications / Q000401:mortality* / Q000503:physiopathology*; D016017:Odds Ratio; D050177:Overweight / Q000150:complications / Q000401:mortality* / Q000503:physiopathology*; D010101:Oxygen Consumption; D010809:Physical Fitness; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012016:Reference Values; D012189:Retrospective Studies
keywords: BMI; CVD; ECG; FAC; HR; MET; body mass index; cardiovascular disease; electrocardiography; functional aerobic capacity; hazard ratio; metabolic equivalent