Minimal Clinically Important Differences (MCIDs) of the Thai Version of the Leicester Cough Questionnaire for Subacute and Chronic Cough.

OBJECTIVES

To investigate the minimal clinically important differences (MCIDs) of the Thai version of the Leicester Cough Questionnaire (LCQ-T) in patients with subacute and chronic cough.

METHODS

Patients with cough for 3 or more weeks were recruited from outpatient clinics. They self-completed the LCQ-T at an initial evaluation and repeated the LCQ-T with a Global Rating of Change scale at follow-up. For the anchor-based method, the MCID was defined as a change in the LCQ scores that corresponded to the smallest improvement in Global Rating of Change score (+2 to +3). For distribution-based methods, the MCIDs were estimated from the standard error of measurement and a half and one-third of the SD of the LCQ score changes from baseline to follow-up.

RESULTS

A total of 107 patients were included. The causes of cough were postinfectious cough/bronchitis (35.5%), asthma (20.6%), rhinosinusitis (16.8%), bronchiectasis (17.8%), and chronic obstructive pulmonary disease (9.3%). The anchor-based method yielded MCIDs of 1.1, 0.4, 0.4, and 0.4 for the total, physical, psychological, and social domains, respectively. The distribution-based method using standard error qof measurement yielded MCIDs of 0.8, 0.3, 0.3, and 0.3, whereas those using a half SD yielded MCIDs of 2.0, 0.6, 0.8, and 0.8 and those using one-third SD yielded MCIDs of 1.4, 0.4, 0.5, and 0.5 for the total, physical, psychological, and social domains, respectively.

CONCLUSIONS

The MCIDs of the LCQ-T for subacute and chronic cough are 1.1, 0.4, 0.4, and 0.4 for the total, physical, psychological, and social domains, respectively. These estimates should be useful in making meaningful interpretations of the changes in quality of life because of cough.