Assessment of Cough in Lung Cancer: Validation of the Manchester Cough in Lung Cancer Scale

Purpose: To date, no external validation of the Manchester Cough in Lung Cancer (MCLC) scale has been carried out beyond the original development study. The aim of this article is to further evaluate this scale in two distinct research study populations, and to further examine its psychometric performance. Methods: This was a secondary analysis of a combined sample from two cough in lung cancer studies. The analysis population comprised of patients enrolled on a cross-sectional cough prevalence study and a longitudinal observational cough study, both in patients with lung cancer. The MCLC scale psychometric properties, including missing data, floor and ceiling effects, internal consistency, intraclass correlation and convergent validity were examined using non-parametric tests. Results: 162 patients from the longitudinal study and 115 patients from the cross-sectional prevalence study were included in these secondary analyses (total N=277). The two cohorts differed in terms of lung cancer stage (p-value=0.03), histology (p-value=0.03), performance status (p=0.003), cough severity (p-value=0.05) and cough impact scores (p-value=0.01). Cronbach’s alpha coefficients for the MCLC scale were 0.87 for both study cohorsts. MCLC scale floor and ceiling effects were minimal for each cohort. The MCLC scale’s intraclass correlation coefficient for clinically stable patients (n=49) was 0.73 (95% CI 0.52-0.85) over 60 days. MCLC scale scores were most strongly correlated with item 31 (‘how much cough in past week’) of the EORTC QLQ C30 + LC13 questionnaire (r = 0.71, p <0.0001) and the cough severity visual analogue scale score (r=0.67, p<0.0001). There was evidence of good discriminant validity with significant interaction between groups defined by the performance status scores and the MCLC scale scores (both p <0.0001). Conclusions: This analysis supports the validity of the MCLC scale for the comprehensive assessment of cough in the context of patients with lung cancer. It is a robust tool, providing data on cough severity, frequency, and its physical, psychological and social impacts.