Health-Related Quality of Life and Its Determinants in Chronic Cough: The Korean Chronic Cough Registry Study

Abstract

Purpose: Chronic cough (CC) is associated with health-related quality of life (HRQoL) impairment. However, the determinants of HRQoL are under-investigated.

Methods: Patients aged 19-80 years with CC were prospectively recruited from 10 referral clinics. Comparisons were made with age- and sex-matched controls (1:4 ratio) selected from a Korean general population survey database; 1) a group without current cough (non-cough controls) and 2) another group without major chronic illnesses (healthy controls). HRQoL was assessed using the EuroQoL 5-dimension (EQ-5D) index. In CC patients, cough-specific patient-reported outcomes (PROs) were additionally measured. Cross-sectional analyses were performed to evaluate demographic and clinical parameters associated with the EQ-5D index of CC patients.

Results: A total of 200 CC patients (137 newly referred with CC and 63 refractory or unexplained CC [RUCC] patients), 800 non-cough controls, and 799 healthy controls were analyzed. The EQ-5D index of CC patients was significantly lower than that of non-cough controls or healthy controls (0.82 ± 0.14 vs 0.92 ± 0.14/0.96 ± 0.08; P < 0.001, respectively). The index was also associated with older age (≥ 60 years), female sex, and comorbidities such as asthma or depression. Among the patients with CC, the index was significantly lower in patients with RUCC than in those with newly referred CC, being treated with codeine or cough neuromodulators, or with cough-related fatigue. In Spearman analyses, the EQ-5D index correlated with cough-specific quality of life and cough severity scores, not with throat sensation or cough trigger scores.

Conclusions: The HRQoL impairment of CC patients was associated with older age, female sex, and comorbidities but it was also affected by cough severity, complications, treatments, and treatment responses. Longitudinal studies are warranted to further understand and improve the HRQoL of CC patients.

Keywords: Cough; cost of illness; health status; quality of life; registries.

Fig. 1. EQ-5D indexes of the (A) HC, NC, and CC groups and (B) newly referred with CC and RUCC patients of the CC group, in means (dots) and 95% confidence intervals (whiskers). P values for between-group comparisons were obtained using a post-hoc Bonferroni test. The relation between EQ-5D index score among the three groups was tested with the Jonckheere-Terpstra statistic on trend (indicated as P for trend).

EQ-5D, EuroQoL 5-dimension; HC, healthy control; NC, non-cough control; CC, chronic cough; RUCC, refractory or unexplained chronic cough.

Fig. 2. Proportional distribution of problem reporting on each of the five domains of the EQ-5D questionnaire between (A) newly referred with CC and (B) RUCC patients.

CC, chronic cough; M, mobility; SC, self-care; UA, usual activities; P/D, pain and discomfort; A/D, anxiety and depression; RUCC, refractory or unexplained chronic cough.

Fig. 3. Correlation of the EQ-5D index with cough-specific patient-reported outcomes of CC patients. (A) Cough severity VAS. (B) Throat sensation VAS. (C) LCQ score. (D) CHQ score.

VAS, visual analog scale; EQ-5D, EuroQoL 5-dimension; LCQ, Leicester Cough Questionnaire; CHQ, Cough Hypersensitivity Questionnaire.