Accuracy of history, wheezing, and forced expiratory time in the diagnosis of chronic obstructive pulmonary disease.

OBJECTIVE

To determine the accuracy of the history and selected elements of the physical examination in the diagnosis of chronic obstructive pulmonary disease (COPD).

DESIGN

Independent blind comparison of the standard clinical examination (evaluating the accuracy of history, wheezing, and forced expiratory time [FET]) with spirometry. The gold standard for diagnosis of COPD was a forced expiratory volume at 1 second (FEV1) below the fifth percentile (adjusted for patient height and age).

SETTING

Seven sites in 6 countries, including investigators from primary care and secondary care settings.

PARTICIPANTS

One hundred sixty-one consecutive patients with varying severity of disease (known COPD, suspected COPD, or no COPD) participated in the study.

MAIN

RESULTS

One hundred sixty-one patients (mean age 65 years, 39% female, 41% with known COPD, 27% with suspected COPD, and 32% normal) were recruited. Mean (+/-SD) FEV1 and forced vital capacity were 1,720 (+/-830) mL and 2,520 (+/-970) mL. The likelihood ratios (LR) for the tested elements of the clinical examination (and their P values on chi2 testing) were: self-reported history of COPD, 5.6 (P <.001); FET greater than 9 seconds, 6.7 (P < 0.01); smoked longer than 40 pack years, 3.3 (P =.001); wheezing, 4.0 (P <.001); male gender, 1.6 (P <.001); and age over 65 years, 1.6 (P =.025). The accuracy of these elements was not appreciably different when reference standards other than FEV1 below the 5th percentile were applied. Only 3 elements of the clinical examination were significantly associated with the diagnosis of COPD on multivariate analysis: self-reported history of COPD (adjusted LR 4.4), wheezing (adjusted LR 2.9), and FET greater than 9 seconds (adjusted LR 4.6). Area under the receiver operating characteristic curve for the model incorporating these 3 factors was 0.86.

CONCLUSIONS

Less emphasis should be placed on the presence of isolated symptoms or signs in the diagnosis of COPD. While numerous elements of the clinical examination are associated with the diagnosis of COPD, only 3 are significant on multivariate analysis. Patients having all 3 of these findings have an LR of 33 (ruling in COPD); those with none have an LR of 0.18 (ruling out COPD).