Differences between remaining ability and loss of capacity in maximum aerobic impairment

Braz J Med Biol Res. 1998 May;31(5):639-46. doi: 10.1590/s0100-879x1998000500006.

Abstract

In the evaluation of exercise intolerance of patients with respiratory diseases the American Medical Association (AMA) and the American Thoracic Society (ATS) have proposed similar classification for rating aerobic impairment using maximum oxygen uptake (VO2max) normalized for total body weight (ml min-1 kg-1). However, subjects with the same VO2max weight-corrected values may have considerably different losses of aerobic performance (VO2max expressed as % predicted). We have proposed a new, specific method for rating loss of aerobic capacity (VO2max, % predicted) and we have compared the two classifications in a prospective study involving 75 silicotic claimants. Logistic regression analysis showed that the disagreement between rating systems (higher dysfunction by the AMA/ATS classification) was associated with age > 50 years (P < 0.005) and overweight (P = 0.04). Interestingly, clinical (dyspnea score) and spirometric (FEV1) normality were only associated with the VO2max, % predicted, normal values (P < 0.01); therefore, in older and obese subjects the AMA/ATS classification tended to overestimate the aerobic dysfunction. We conclude that in the evaluation of aerobic impairment in patients with respiratory diseases, the loss of aerobic capacity (VO2max, % predicted) should be used instead of the traditional method (remaining aerobic ability, VO2max, in ml min-1 kg-1).

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Disability Evaluation*
  • Exercise Tolerance*
  • Exercise*
  • Female
  • Humans
  • Inspiratory Capacity
  • Male
  • Middle Aged
  • Oxygen Consumption*
  • Prospective Studies
  • Respiratory Function Tests
  • Respiratory Tract Diseases / physiopathology*