The accuracy of patient history, wheezing, and laryngeal measurements in diagnosing obstructive airway disease. CARE-COAD1 Group. Clinical Assessment of the Reliability of the Examination-Chronic Obstructive Airways Disease

Abstract

Context: The accuracy of the clinical examination in detecting obstructive airway disease (OAD) is largely unknown because of a paucity of methodologically rigorous studies.

Objective: To determine the accuracy of patient history, wheezing, laryngeal height, and laryngeal descent in the diagnosis of OAD.

Design: Comparison study conducted from November 3, 1998, to December 4, 1998, evaluating 4 clinical examination elements for diagnosis of OAD vs the gold standard of forced expiratory volume in 1 second (FEV1) and FEV1-forced vital capacity (FVC) ratio less than the fifth percentile (adjusted for patient height, age, and sex).

Setting: Twenty-five sites, including primary care and referral practices, in 14 countries.

Participants: A total of 309 consecutive patients were recruited (mean age, 56 years; 43% female), 76 (25%) with known chronic OAD, 114 (37%) with suspected chronic OAD, and 119 (39%) with neither known nor suspected OAD.

Main outcome measures: Sensitivity, specificity, and likelihood ratios (LRs) for each of the 4 elements of the clinical examination compared with the gold standard.

Results: Mean FEV1 and FVC values were 2.1 L/s and 2.9 L; 52% had an FEV1 and FEV1-FVC ratio less than the fifth percentile. The LR for wheezing was 2.7 (95% confidence interval [CI], 1.7-4.2) and was not statistically significant in the multivariate model. The LR for laryngeal descent ranged from 0.9 (95% CI, 0.5-1.4) to 1.2 (95% CI, 0.4-3.4), depending on the cut point chosen, and did not enter the multivariate model. Only 4 of the history or physical examination elements we tested were significantly associated with the diagnosis of OAD on multivariate analysis: smoking for more than 40 pack-years (LR, 8.3), self-reported history of chronic OAD (LR, 7.3), maximum laryngeal height of 4 cm [corrected] or less (LR, 2.8), and age at least 45 years (LR, 1.3). Patients having all 4 findings had an LR of 220 (ruling in OAD); those with none had an LR of 0.13 (ruling out OAD). The area under the receiver operating characteristic curve for the model incorporating these 4 factors was 0.86.

Conclusions: Further research is needed to validate our model, but in the meantime, our data suggest that less emphasis should be placed on the presence of individual symptoms or signs (such as wheezing or laryngeal descent) in the diagnosis of OAD.