Table 4– Receiver-operating characteristic (ROC) analysis comparing the ability of absolute and % predicted 6-min walk distance (6MWD) to predict 2-yr mortality
ROC curve area (95% CI)Optimal thresholdSensitivity/specificityp-value
At baseline
 Absolute 6MWD0.74 (0.63–0.86)<295 m0.83/0.59<0.0005
 6MWD % pred
  Enright 110.71 (0.59–0.83)<51%0.75/0.56<0.005
  Troosters 130.73 (0.62–0.85)<43%0.79/0.57<0.001
  Gibbons 120.75 (0.64–0.85)<43%0.75/0.60<0.0005
  Chetta 100.74 (0.63–0.85)<53%0.75/0.57<0.001
On treatment
 Absolute 6MWD0.77 (0.64–0.90)<296 m0.87/0.66<0.005
 6MWD % pred
  Enright 110.72 (0.56–0.87)<53%0.67/0.66<0.01
  Troosters 130.76 (0.63–0.90)<45%0.80/0.67<0.005
  Gibbons 120.78 (0.64–0.91)<44%0.87/0.72<0.005
  Chetta 100.78 (0.65–0.91)<53%0.87/0.71<0.005