Performance of CODE questionnaire (COPD detection questionnaire) cut-point scores in screening for airway obstruction
| CODE score | Total subjects n | COPD subjects n | Sensitivity | Specificity | PPV | NPV | Correctly classified |
| 0 | 20 | 0 | NA | NA | NA | NA | NA |
| 1 | 72 | 1 | 100 | 5.41 | 21.52 | 100 | 24.89 |
| 2 | 100 | 19 | 98.96 | 24.59 | 25.40 | 98.91 | 39.91 |
| 3 | 117 | 22 | 79.17 | 46.49 | 27.74 | 89.58 | 53.22 |
| 4 | 76 | 19 | 56.25 | 72.16 | 34.39 | 86.40 | 68.88 |
| 5 | 62 | 24 | 36.46 | 87.57 | 43.21 | 84.15 | 77.04 |
| 6 | 19 | 11 | 11.46 | 97.84 | 57.89 | 80.98 | 80.04 |
Data are presented as %, unless otherwise stated. COPD: chronic obstructive pulmonary disease; PPV: positive predictive value; NPV: negative predictive value; NA: not applicable.