The accuracy of patient history, wheezing, and laryngeal measurements in diagnosing obstructive airway disease

Context The accuracy of the clinical examination in detecting obstructive a irway disease (OAD) is largely unknown because of a paucity of methodologic ally 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, 199 8, evaluating 4 clinical examination elements for diagnosis of OAD vs the g old standard of forced expiratory volume in 1 second (FEV1) and FEV1-forced vital capacity (FVC) ratio less than the fifth percentile (adjusted for pa tient height, age, and sex). Setting Twenty-five sites, including primary care and referral practices, i n 14 countries. Participants A total of 309 consecutive patients were recruited (mean age, 56 years; 43% female), 76 (25%) with known chronic OAD, 1 14 (37%) with sus pected 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 g old standard. Results Mean FEV1 and FVC values were 2.1 L/s and 2.9 L; 52% had an FEV1 an d 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 signifi cant 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 ch osen, and did not enter the multivariate model. Only 4 of the history or ph ysical examination elements we tested were significantly associated with th e diagnosis of OAD on multivariate analysis: smoking for more than 40 pack- years (LR, 8.3), self-reported history of chron ic OAD (LR, 7.3), maximum l aryngeal height of at least 4 cm (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); thos e with none had an LK 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 me antime, our data suggest that less emphasis should be placed on the presenc e of individual symptoms or signs (such as wheezing or laryngeal descent) i n the diagnosis of OAD.