Background: Numerous decision aids have been developed recently, but the value they add above that of the initial clinical assessment is not well known.
Aim: To quantify whether a formal decision aid for chronic obstructive pulmonary disease (COPD) adds diagnostic information, above the physician's clinical assessment.
Design and setting: Subanalysis of a diagnostic study in Dutch primary care.
Method: Sixty-five primary care physicians included 357 patients who attended for persistent cough and were not known to have COPD. The physicians estimated the probability of COPD after short history taking and physical examination. After this, the presence or absence of COPD was determined using results of extensive diagnostic work-up. The extent to which an 8-item decision aid for COPD, which included only symptoms and signs, added diagnostic value above the physician's estimation was quantified by the increase of the area under the receiver operating characteristic curve (ROC area), and the improvement in diagnostic risk classification across two classes: 'low probability of COPD' (<20%) and 'possible COPD' (≥20%).
Results: One hundred and four patients (29%) had COPD. Adding the decision aid to the clinical assessment increased the ROC area from 0.75 (95% confidence interval [CI] = 0.70 to 0.81) to 0.84 (95% CI = 0.80 to 0.89) (P<0.005), and improved the diagnostic risk classification of the patients, such that 35 fewer patients needed spirometry testing and eight fewer COPD cases were missed.
Conclusion: A short decision aid for COPD added diagnostic value to the physician's clinical assessment.