Background and objectives: The chronic obstructive pulmonary disease (COPD) is a highly undiagnosed disease. The use of short screening questionnaires designed to detect chronic airflow obstruction may help to the early diagnosis of COPD.
Patients and method: This was an observational, cross-sectional epidemiological study aimed to validate the translated into Spanish version of the COPD-PS questionnaire. Socio-demographic and clinical data of participants were collected, as well as their answers to the COPD-PS and EQ-5D questionnaires. The ratio FEV(1)/FEV(6) was measured with the COPD-6 device. The psychometric properties of the questionnaire and the diagnostic yield of the FEV(1)/FEV(6) ratio were analysed, both referred to the gold standard of post-bronchodilator FEV(1)/FVC < 0.7.
Results: Ten primary care centers participated in the study and included 94 controls and 79 cases with chronic airflow obstruction. Questionnaire characteristics were: feasibility, 2.3% of participants did not answer at least one item; mean time to fill the questionnaire was 47.7 seconds; 4.7% of individuals had a 0 score. Validity, moderate correlation with EQ-5D scores and moderate-high with FEV(1); the scores of COPD-PS were related to all parameters associated with COPD. A cut off of 4 units had the best sensitivity/specificity ratio and correctly classified 78% of participants. For the FEV(1)/FEV(6) ratio, a cut off of 0.75 correctly classified 85% of individuals.
Conclusions: The COPD-PS questionnaire demonstrated good psychometric properties. A cut off score of 4 has excellent predictive value. A ratio of 0.75 in the FEV(1)/FEV(6) provides an excellent correlation with the ratio FEV(1)/FVC and is useful for the identification of individuals with chronic airflow obstruction.
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