Table 1. Baseline characteristics of each group (n = 1,799).
| Variables | CC cases (n = 200) | NC (n = 800) | HC (n = 799) | P value | |
|---|---|---|---|---|---|
| Age (yr) | 54.9 ± 15.1 | 54.9 ± 15.4 | 54.5 ± 15.4 | 0.908 | |
| Sex | 1.000 | ||||
| Male | 71 (35.5) | 284 (35.5) | 284 (35.5) | ||
| Female | 129 (64.5) | 516 (64.5) | 515 (64.5) | ||
| BMI (kg/m2)* | 24.6 ± 4.8 | 24.1 ± 3.2 | 23.1 ± 3.1 | < 0.001 | |
| < 18.5 kg/m2 | 7 (3.6) | 17 (2.1) | 44 (5.5) | < 0.001 | |
| 18.5–24.9 kg/m2 | 109 (55.3) | 485 (60.8) | 551 (69.1) | ||
| 25.0–29.9 kg/m2 | 63 (32.0) | 268 (33.6) | 180 (22.6) | ||
| ≥ 30 kg/m2 | 18 (9.1) | 28 (3.5) | 22 (2.8) | ||
| Smoking status* | < 0.001 | ||||
| Never | 151 (75.5) | 538 (67.4) | 544 (68.4) | ||
| Ex-smoker | 39 (19.5) | 130 (16.3) | 109 (13.7) | ||
| Current smoker | 10 (5.0) | 130 (16.3) | 142 (17.9) | ||
| Comorbidities | |||||
| Asthma* | 22 (11.1) | 30 (3.8) | N/A | < 0.001† | |
| Allergic rhinitis* | 27 (13.5) | 89 (11.3) | N/A | 0.394† | |
| Pulmonary tuberculosis* | 7 (3.5) | 35 (4.4) | N/A | 0.590† | |
| Hypertension* | 51 (25.8) | 256 (32.0) | N/A | 0.521† | |
| Diabetes mellitus* | 19 (9.6) | 89 (11.1) | N/A | 0.088† | |
| Dyslipidemia* | 20 (10.1) | 120 (15.0) | N/A | 0.072† | |
| IHD* | 5 (2.5) | 30 (3.8) | N/A | 0.396† | |
| Stroke* | 2 (1.0) | 19 (2.4) | N/A | 0.228† | |
| Chronic liver disease* | 2 (1.0) | 15 (1.9) | N/A | 0.396† | |
| Chronic kidney disease* | 2 (1.0) | 4 (0.5) | N/A | 0.343† | |
| Malignancy* | 4 (2.0) | 35 (4.4) | N/A | 0.123† | |
| Depression* | 4 (2.0) | 58 (7.3) | N/A | 0.006† | |
| EQ-5D index | 0.82 ± 0.14 | 0.92 ± 0.14 | 0.96 ± 0.08 | < 0.001 | |
| EQ-VAS | 63.7 ± 18.0 | 77.5 ± 57.6 | 77.5 ± 36.8 | 0.005 | |
CC, chronic cough; NC, non-cough control; HC, healthy control; BMI, body mass index; IHD, ischemic heart disease; EQ-5D, EuroQoL 5-dimension; VAS, visual analog scale.
*Numbers of patients with missing data are as follows: BMI (n = 7), smoking status (n = 6), asthma (n = 1), allergic rhinitis (n = 14), pulmonary tuberculosis (n = 1), hypertension (n = 2), diabetes mellitus (n = 1), dyslipidemia (n = 1), ischemic heart disease (n = 1), stroke (n = 1), chronic liver disease (n = 1), chronic kidney disease (n = 1), malignancy (n = 1), and depression (n = 1).
†P value between CC and NC.