title: Differences in cardiopulmonary exercise test results by American Thoracic Society/European Respiratory Society-Global Initiative for Chronic Obstructive Lung Disease stage categories and gender.
abstract: BACKGROUND
  The American Thoracic Society (ATS)/European Respiratory Society (ERS)-Global Initiative for Chronic Obstructive Lung Disease (GOLD) has developed a new staging system based on the degree of airflow obstruction. Its validity to predict exercise capacity as an outcome has not been extensively studied. We hypothesized that exercise performance measured by cardiopulmonary exercise test (CPET) results should decline significantly with each disease stage, independent of gender.
  
  
  METHODS
  We examined 453 consecutive incremental CPET and pulmonary function tests performed in patients who had been referred to a single respiratory physiology laboratory in a tertiary care hospital. They were divided into a control group (normal lung function) and ATS/ERS-GOLD stages 1 to 4. We measured anthropometrics, peak work (in watts), peak oxygen uptake (in liters per kilogram per minute and percent predicted), breathing reserve (in percent predicted), and arterial blood gas response. We compared these results between different stages and genders.
  
  
  RESULTS
  The mean (+/- SD) age for the entire group was 64 +/- 11 years, the mean FEV(1) was 66 +/- 28%, and the mean body mass index (BMI) was 27.2 +/- 5.82 kg/m(2). Patients in stage 4 were significantly younger (p < 0.001) and had a lower BMI (p < 0.02) compared to those in stages 1 to 3. There was a significant reduction in exercise capacity for patients at every stage except for those in stage 1, who had values similar to those of the control group. Women had better lung function and exercise capacity than men, but the difference disappeared when adjusted by COPD stages.
  
  
  CONCLUSIONS
  The ATS/ERS-GOLD staging system can be used to indicate differences in exercise capacity in patients with COPD stages 2 to 4 and to normalize apparent gender disparities. The value of differentiating stage 1 patients requires further studies with different outcomes.
authors.affiliation: Division of Pulmonary, Critical Care and Sleep Medicine, Caritas St. Elizabeth's Medical Center, Tufts University School of Medicine, 736 Cambridge St, Boston, MA 02135, USA. vpinto@copdnet.org
authors.forename: Victor M
authors.initials: VM
authors.lastname: Pinto-Plata
authors.forename: Romulo A
authors.initials: RA
authors.lastname: Celli-Cruz
authors.forename: Carlos
authors.initials: C
authors.lastname: Vassaux
authors.forename: Luis
authors.initials: L
authors.lastname: Torre-Bouscoulet
authors.forename: Asante
authors.initials: A
authors.lastname: Mendes
authors.forename: John
authors.initials: J
authors.lastname: Rassulo
authors.forename: Bartolome R
authors.initials: BR
authors.lastname: Celli
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange; D012129:Respiratory Function Tests; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology