Validation of a questionnaire to screen chronic obstructive respiratory diseases

Spirometry is the gold standard for diagnosing chronic obstructive respiratory diseases (CORD), but it is not widely available in primary healthcare in Vietnam. We aimed to validate a simple CORD Screening Questionnaire (CORD-SQ) for the Vietnamese population to screen subjects requiring spirometry.In a cross-sectional study, 589 volunteers seen in a primary healthcare unit were submitted to the CORD-SQ. This questionnaire included four items (cumulative smoking, history of tuberculosis, current breathlessness and wheezing or whistling) with a total score ranging from 0 to 6. The cut-off point of the CORD-SQ was previously determined as a predictor of CORD, which was last defined by spirometry (forced expiratory volume in 1 second/forced vital capacity < lower limit of normal) measured in each subject.The prevalence of CORD was 10% among the 517 subjects with non-asthmatic history. With a cut-off point of 2 for the CORD-SQ, the sensitivity and specificity were 69% and 91%, respectively, with a 46% positive predictive value and 94% negative predictive value. The area under the receiver operating characteristic curve of the CORD-SQ to discriminate the CORD was 0.83 (95% CI 0.75-0.90).In the non-asthmatic Vietnamese primary health care population, the simple CORD-SQ efficiently identifies the people at risk of CORD, requiring spirometry..