Published in:
Open Access 01-12-2018 | Research article
The cutoff point of clinical chronic obstructive pulmonary disease questionnaire for more symptomatic patients
Published in: BMC Pulmonary Medicine | Issue 1/2018
Login to get accessAbstract
Background
An adequate threshold for the Clinical Chronic Obstructive Pulmonary Disease (COPD) Questionnaire (CCQ) defining more symptomatic COPD patients has not been determined. We aimed to determine the efficacy of the CCQ and the appropriate CCQ threshold for more symptomatic COPD patients.
Methods
COPD patients aged > 40 years who smoked/had smoked ≥10 packs/year were prospectively enrolled over 1 year from three South Korean hospitals (n = 126). Correlations between the CCQ and St. George’s Respiratory Questionnaire (SGRQ), COPD Assessment Test (CAT), the modified Medical Round Council (mMRC) scale, lung function, and exercise capacity were evaluated. “More symptomatic patients” were those with an SGRQ score ≥ 25. Area under the receiver operating curve and classification and regression tree analyses were performed to determine the CCQ threshold equivalent to an SGRQ score ≥ 25.
Results
The CCQ significantly correlated with the SGRQ, CAT, and mMRC scale (r = 0.76, 0.69, and 0.53, respectively). A CCQ cutoff of 1.4 predicted an SGRQ score of 25 better than others. A CCQ score of 1.4 was a significant determinant of an SGRQ score ≥ 25 even after adjusting for potential confounders.
Conclusions
The CCQ was correlated with other symptom indicators, lung function, and exercise capacity. A CCQ cutoff of 1.4 agreed better than CCQ cutoff of 1.0, suggested by guideline, and this cutoff value may identify more symptomatic COPD patients well.
Trial registration
ClinicalTrials.gov Identifier: NCT02527486. Date of registration: December 19, 2014, retrospectively registered.