Impact of Chronic Cough on Health-Related Quality of Life in the Korean Adult General Population: The Korean National Health and Nutrition Examination Survey 2010-2016

Abstract

Purpose: Chronic cough is a prevalent condition in the community and may pose considerable impairment to quality of life (QoL). However, its disease burden remains largely undefined in the general population. The present study investigated the relationship between chronic cough and health-related QoL in a Korean nationwide population database, with an emphasis on clinical conditions which may confound the impact of cough.

Methods: This study analyzed cross-sectional datasets of adults (aged ≥ 40 years) in the Korean National Health and Nutrition Examination Survey 2010-2016. Health-related QoL was assessed using the 3-level EuroQoL 5-dimension component (EQ-5D-3L) index score. The presence of chronic cough and other conditions were defined using structured questionnaires.

Results: The prevalence of chronic cough was 3.48% ± 0.17% among adults aged ≥ 40 years. The overall EQ-5D-3L index score was significantly lower in subjects with than without chronic cough (0.79 ± 0.01 vs. 0.86 ± 0.00, P < 0.001). In subgroup analyses by age and sex, chronic cough had a notably large impact on QoL in women aged ≥ 65 years (vs. those without chronic cough: 0.55 ± 0.04 vs. 0.70 ± 0.01, P < 0.001), although the mean difference in the scores exceeded the minimally important difference score of 0.05 in all subgroups. In multivariate analyses, chronic cough was significantly associated with QoL, independent of confounders including depression, arthritis, asthma, and chronic obstructive pulmonary disease. In dimension analyses, chronic cough was more associated with anxiety/depression, pain/discomfort, and usual activities than with self-care or mobility in the EQ-5D.

Conclusions: The present study demonstrated significant associations between chronic cough and health-related QoL in a nationwide large general adult population aged ≥ 40 years, which were independent of clinical confounders. The impact of chronic cough was greater in women aged ≥ 65 years. These findings indicate a considerable burden of chronic cough in the general population and warrant further investigations to assess the disease burden of chronic cough in a global scale.

Keywords: Cough; burden of disease; cross-sectional studies; epidemiology; nutrition surveys; patient health questionnaire; population surveillance; quality of life.

Fig. 1. Histograms of EQ-5D-3L index scores in subjects with and without chronic cough (aged ≥ 40 years) in the KNHANES 2010–2016.

EQ-5D-3L, 3-level EuroQoL 5-dimension component; KNHANES, Korean National Health and Nutrition Examination Survey.

Fig. 2. EuroQoL EQ-5D-3L index scores in subjects according to the presence of chronic cough (aged ≥ 40 years) classified by (A) gender and (B) sex-age subgroups in the KNHANES 2010–2016. The scores are presented as weighted means ± standard errors.

EQ-5D-3L, 3-level EuroQoL 5-dimension component; KNHANES, Korean National Health and Nutrition Examination Survey.

Fig. 3. Associations between chronic cough and each EQ-5D dimension score in the KNHANES 2010–2016. (A) Domain scores in all adults (≥ 40 years), and (B-F) each domain score according to age and sex. In each dimension, level 1 (no problems) served as the reference, and level 2 (some problems) and level 3 (extreme problems) were merged to “some or extreme problem.” ORs were calculated from multivariate logistic regressions adjusted for age, sex, smoking, body mass index, education level, household income, occupation, arthritis, depression, asthma, chronic obstructive pulmonary disease, hypertension, dyslipidemia, angina/myocardial infarction, and stroke.

EQ-5D, EuroQoL 5-dimension component; KNHANES, Korean National Health and Nutrition Examination Survey; OR, odds ratio; CI, confidence interval.

Fig. 4. EQ-5D-3L index scores according to the presence of chronic diseases among subjects in all adult subjects (aged ≥ 40 years) and elderly women (aged ≥ 65 years) in the KNHANES 2010–2016. (A) Entire sample analyses and (B) subgroup analyses excluding subjects with depression. Horizontal dotted lines and grey boxes indicate the mean score and standard error margins of the EQ-5D-3L index score in subjects with chronic cough. Vertical dotted lines are positioned to differentiate chronic cough from other chronic conditions. Error bars indicate standard error in the EQ-5D-3L index scores in each chronic condition. Conditions other than chronic cough were sorted by EQ-5D-3L index score (low to high) in all adult dataset (≥ 65 years).

EQ-5D, EuroQoL 5-dimension component; KNHANES, Korean National Health and Nutrition Examination Survey; COPD, chronic obstructive pulmonary disease. ^*COPD was defined as a condition requiring current treatment; other medical conditions in this figure indicate a diagnostic history and current disease. ^†Allergic rhinitis was assessed only in the KNHANES 2013–2015 study.