Summary of case detection strategies evaluated
| Testing technology | Eligibility criteria | Sensitivity, %* | Specificity, %* |
|---|---|---|---|
| (S1) All patients | |||
| S1a: CDQ ≥ 17 points | None | 91.0 | 49.0 |
| S1b: Flow metre (with bronchodilator) | 80.0 | 94.0 | |
| S1c: CDQ ≥ 17 points + flow metre (with bronchodilator) | 72.0 | 97.0 | |
| (S2) Symptomatic patients | |||
| S2a: Flow metre (without bronchodilator) | ≥ 1 respiratory symptom† | 81.5 | 88.9 |
| (S3) Smoking history | |||
| S3a: CDQ ≥ 19.5 points | Past or current smoker Age ≥ 50 yr | 64.5 | 65.2 |
| S3b: CDQ ≥ 16.5 points | 87.5 | 38.8 | |
| S3c: Flow metre (without bronchodilator) | 79.9 | 84.4 | |
| S3d: CDQ ≥ 17 points + flow metre (with bronchodilator) | 74.4 | 97.0 |
Note: CDQ = COPD diagnostic questionnaire, COPD = chronic obstructive pulmonary disease.
↵* Sensitivity and specificity values are derived from the literature and further details have been provided previously. (16) Sensitivity and specificity values relate to the outcome of the case detection test only; patients testing positive are then referred for diagnostic spirometry, which we assume to have 100% accuracy.
↵† Respiratory symptoms defined as the presence of chronic cough in the absence of a cold, any wheeze, phlegm in the absence of a cold, or dyspnea, measured using the Medical Research Council dyspnea scale with a score of 2–5 indicating the presence of dyspnea, in the past year.