Figures
- FIGURE 1
The prevalence of chronic cough in different regions of China.
- FIGURE 2
Association of chronic cough with quality of life and respiratory exacerbations: a) physical component summary (PCS) score; b) mental component summary (MCS) score; c) emergency; and d) hospital admission. Adjusted for age, sex, urbanisation, body mass index, cigarette smoking, biomass, annual mean particulate matter with a diameter <2.5 μm (PM2.5), education, occupational exposure, visible mould spots in the current residence, history of pneumonia or bronchitis during childhood, parental history of respiratory diseases and allergic rhinitis. The subgroup variables were not adjusted in the corresponding subgroup analysis for themselves, except that age was still adjusted as continuous variable for the subgroup analysis conducted among those aged 20–49 and ≥50 years. SAD: small airway dysfunction.
Tables
- TABLE 1
Demographics and risk factors by diagnosis of chronic cough in the general Chinese adult population
Variables No chronic cough Chronic cough p-value Subjects n 49 006 1985 Men 20 255 (50.0) 1191 (64.0) 0.0031 Age years 43.5±0.8 52.0±1.5 <0.0001 Urban residents 31 637 (51.6) 1242 (52.1) 0.9135 Education level 0.0359 Primary school or less 12 090 (22.2) 665 (33.0) Middle and high school 28 113 (52.5) 1057 (46.8) College and higher 8803 (25.3) 263 (20.2) Cigarette smoking 0.0001 Never-smoker 35 466 (69.4) 963 (45.9) Ever-smoker# 13 540 (30.6) 1022 (54.1) Passive smoking at home¶ 17 130 (47.8) 470 (52.9) 0.2546 Biomass use 12 967 (25.8) 661 (32.4) 0.0747 Annual mean PM2.5 exposure µg·m−3 70.7±2.9 72.3±3.6 0.3203 Occupational exposure 11 608 (24.5) 719 (37.3) 0.0017 Visible mould spots in the current residence 0.2377 Rarely 36 152 (69.1) 1319 (62.3) Sometimes 10 098 (24.2) 487 (28.7) Often 2265 (6.7) 170 (9.0) History of pneumonia or bronchitis during childhood 2227 (4.9) 217 (11.3) 0.0033 Parental history of respiratory diseases 8070 (16.5) 539 (24.4) 0.0006 Body mass index kg·m−2 23.6±0.1 23.9±0.2 0.1855 Allergic rhinitis 4676 (10.6) 407 (25.0) 0.0006 Values are weighted and shown as n (%) or mean±se unless otherwise indicated. p-values are weighted, taking into account the multistage cluster sampling design and based on χ2 test for categorical variables or t-test for continuous variables. PM2.5: particulate matter with a diameter <2.5 µm. #: ever-smoker was defined as having smoked equal to or >100 cigarettes in the lifetime; ¶: demographics of passive smoking at home were shown for never-smokers.
- TABLE 2
Age-specific and age-standardised prevalence of chronic cough in the general adult population
Variables Total Men Women p-value Total 3.6 (3.1–4.1) 4.6 (3.9–5.4) 2.6 (2.1–3.3) 0.0005 Age years 20–49 2.4 (1.9–3.1) 3.0 (2.2–4.2) 1.7 (1.1–2.7) 0.0433 ≥50 6.0 (5.3–6.8) 7.7 (6.7–8.8) 4.3 (3.6–5.0) <0.0001 p-value for difference <0.0001 <0.0001 <0.0001 COPD# No 3.2 (2.7–3.7) 4.1 (3.4–5.0) 2.3 (1.8–3.0) 0.0006 Yes 6.0 (3.5–10.0) 5.2 (4.0–6.7) 6.9 (2.5–18.1) 0.5777 p-value for difference 0.0845 0.1155 0.1846 SAD¶ No 2.8 (2.3–3.5) 3.7 (3.0–4.5) 2.0 (1.5–2.8) 0.0010 Yes 4.4 (3.7–5.2) 5.4 (4.2–6.9) 3.2 (2.4–4.2) 0.0101 p-value for difference 0.0039 0.0229 0.0233 Values are represented as percentage (95% confidence interval). p-value for difference is for the comparison of binary variables. All the calculations of p-values are weighted, taking into account the multistage cluster sampling design and based on χ2 test. SAD: small airway dysfunction. #: COPD was defined as those individuals with post-bronchodilator FEV1/FVC <70%. ¶: SAD was diagnosed on the basis of at least two of the following three indicators of lung function being <65% of predicted: maximal mid-expiratory flow, forced expiratory flow (FEF) 50% and FEF 75% after bronchodilator inhalation.
- TABLE 3
Multiple adjusted odds ratios of chronic cough in the general Chinese adult population
Variables OR (95% CI) p-value Male 0.93 (0.63–1.37) 0.7045 Age (10 years) 1.43 (1.26–1.61) <0.0001 Rural resident 0.84 (0.59–1.19) 0.3094 Smoking status Never-smoker 1.00 (Reference) Ever-smoker# 2.61 (2.10–3.25) <0.0001 Biomass use 1.04 (0.86–1.26) 0.6621 Annual mean PM2.5 µg·m−3 <50 1.00 (Reference) - 50–75 0.96 (0.59–1.57) 0.8784 ≥75 1.05 (0.62–1.79) 0.8471 Education level Primary school and lower 1.00 (Reference) - Middle and high school 0.80 (0.61–1.05) 0.1083 College and higher 0.97 (0.68–1.39) 0.8770 Occupational exposure 1.41 (1.10–1.80) 0.0086 Visible mould spots in the current residence Rarely 1.00 (Reference) - Sometimes 1.31 (0.91–1.90) 0.1414 Often 1.19 (0.73–1.93) 0.4652 History of pneumonia or bronchitis during childhood 2.23 (1.49–3.34) 0.0006 Parental history of respiratory diseases 1.23 (0.95–1.59) 0.1165 Body mass index kg·m−2 <18.5 1.45 (0.97–2.16) 0.0662 18.5–24.9 1.00 (Reference) - ≥25 1.23 (0.94–1.61) 0.1197 Allergic rhinitis 2.84 (1.98–4.09) <0.0001 The variables listed in the table are all included in the model. The logistic regression analyses are weighted, taking into account the multistage cluster sampling design. OR: odds ratio; 95% CI: 95% confidence interval; PM2.5: particulate matter with a diameter <2.5 µm. #: ever-smoker was defined as having smoked equal to or >100 cigarettes in the lifetime.
- TABLE 4
Clinical characteristics and use of healthcare resources by diagnosis of chronic cough
Variables No chronic cough Chronic cough p-value Subjects n 49 006 1985 Lung function# FEV1/FVC % 82.0±0.4 75.2±1.2 <0.0001 FEV1 % pred 99.8±0.9 94.5±2.5 0.0155 FEV1/FVC <70% 4420 (8.1) 488 (22.8) 0.0010 MMEF % pred 76.0±1.0 62.6±2.8 <0.0001 FEF 50% pred 88.4±1.0 74.4±3.4 <0.0001 FEF 75% pred 77.2±1.3 62.7±2.6 <0.0001 SAD¶ 15 991 (28.3) 988 (48.0) 0.0017 Positive bronchodilator reversibility+ 3059 (6.1) 222 (13.0) 0.0315 Short form (SF)-12 scores PCS scores 52.6±0.2 48.7±0.6 <0.0001 MCS scores 54.1±0.3 53.1±0.6 0.0656 Comorbidities Hypertension 3846 (6.4) 309 (13.1) 0.0116 Coronary heart disease 698 (1.9) 87 (3.2) 0.3501 Diabetes 1203 (2.6) 96 (3.9) 0.2589 Acute exacerbation of respiratory symptoms in the last 12 months Emergency 174 (0.5) 89 (3.5) 0.0042 Hospital admission 167 (0.4) 119 (5.5) 0.0002 Values are weighted and shown as n (%) or mean±se. All the calculations of p-value are weighted, taking into account the multistage cluster sampling design and based on χ2 test for categorical variables or t-test for continuous variables. FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; MMEF: maximal mid-expiratory flow; FEF50%: forced expiratory flow at 50% of the FVC; FEF 75%: forced expiratory flow at 75% of the FVC; SAD: small airway dysfunction; PCS: physical component summary; MCS: mental component summary. #: the parameters were measured at 20 min after inhalation of 400 µg of salbutamol; ¶: SAD was diagnosed on the basis of at least two of the following three indicators of lung function being <65% of predicted – maximal mid-expiratory flow, forced expiratory flow (FEF) 50% and FEF 75% after bronchodilator inhalation. +: a positive bronchodilator reversibility test was defined as an increase in post-bronchodilator forced expiratory volume in 1 s of >12% and >200 mL from baseline, 20 min after inhalation of 400 µg of salbutamol.
- TABLE 5
Associations of chronic cough with lung function after bronchodilator inhalation
Variables OR or β (95% CI) p-value FEV1/FVC −3.30 (−4.93– −1.66) 0.0005 FEV1 %pred −4.42 (−8.89–0.05) 0.0522 FEV1/FVC <70% 1.59 (1.13–2.23) 0.0106 MMEF % pred −5.73 (−9.06– −2.40) 0.0020 FEF 50% pred −7.64 (−12.16– −3.11) 0.0023 FEF 75% pred −6.51 (−10.29– −2.74) 0.0019 SAD# 1.47 (1.14–1.89) 0.0049 Positive bronchodilator reversibility¶ 1.87 (1.01–3.47) 0.0472 Adjusted for age, sex, urbanisation, body mass index, cigarette smoking, biomass, annual mean PM2.5, education, occupational exposure, visible mould spots in the current residence, history of pneumonia or bronchitis during childhood, parental history of respiratory diseases and allergic rhinitis. The logistic or linear regression analyses are weighted, taking into account the multistage cluster sampling design. FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; MMEF: maximal mid-expiratory flow; FEF 50%: forced expiratory flow at 50% of the FVC; FEF 75%: forced expiratory flow at 50% of the FVC; SAD: small airway dysfunction. #: SAD was diagnosed on the basis of at least two of the following three indicators of lung function being <65% of predicted – MMEF, FEF 50% and FEF 75% after bronchodilator inhalation; ¶: a positive bronchodilator reversibility test was defined as an increase in post-bronchodilator forced expiratory volume in 1 s of >12% and >200 mL from baseline, 20 min after inhalation of 400 µg of salbutamol.
Supplementary Material
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Supplementary material 00075-2022.SUPPLEMENT
