Background:

COPD is highly underdiagnosed, thus applying clinical prediction scales such as the COPD Diagnostic Questionnaire (CDQ) helps to address this problem.

Objective:

To evaluate the criterion validity and intra-rater reproducibility of the questionnaire CDQ in a Colombian population.

Materials and methods:

A prospective cohort study. The reproducibility was assessed with the Kappa statistic and the intraclass correlation coefficient (ICC). Validity was established with the score obtained from the CDQ questionnaire and the spirometry values (FEV1/ FVC <0.7 post B2). The area under the curve of the receiver operating characteristics (ACOR), sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated. A statistically significant p <0.05 was considered.

Results:

A total of 1,423 subjects were recruited. The ICC between the two moments of the questionnaire evaluation was 0.781 (95%CI: 0.744-0.813), and a kappa of 0.65 (p <0.001) was found for the scoring systems with low probability of COPD CDQ ≤ 16.5, intermediate probability of CDQ COPD > 16.5 and < 19.5, and high probability of CDQ COPD ≥ 19.6. The ACOR was 0.68 (95%CI: 0.647-0.712), a sensitivity of 79% and a specificity of 44% were obtained for a score ≥16.5, with a PPV of 26% and a NPV of 86%.

Conclusions:

The CDQ questionnaire has a regular performance for the diagnosis of COPD with an ACOR similar to other questionnaires, it can be useful in underdiagnosed patients. The optimal cut-off point for this population was 16.5.

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