Table 1.
Baseline Characteristics of the Study Subjects
| Characteristics | Total Group (n=612) | GOLD 1 (n=285) | GOLD 2 (n=270) | GOLD 3–4 (n=57) | P values |
|---|---|---|---|---|---|
| Sex, male | 543(88.7) | 240(84.2) | 246(91.1) | 57(100) | 0.001 |
| Age, yr | 63.7±7.3 | 63.1±7.2 | 63.8±7.6 | 66.2±5.4 | 0.011 |
| BMI, kg/m 2 | 22.1±3.4 | 22.5±3.1 | 22.1±3.6 | 19.8±3.0 | <0.001 |
| Smoking status※ | <0.001 | ||||
| Never smoker | 99(16.2) | 59(20.7) | 37(13.7) | 3(5.3) | |
| Former smoker | 179(29.2) | 65(22.8) | 76(28.1) | 38(66.7) | |
| Current smoker | 333(54.4) | 160(56.1) | 157(58.1) | 16(28.1) | |
| Smoke index, pack-yrs | 30.9±29.8 | 29.0±30.0 | 29.5±26.9 | 46.7±36.9 | <0.001 |
| Passive smoker | 186(30.4) | 80(28.1) | 83(30.7) | 23(40.4) | 0.181 |
| Occupational exposure※ | 368(60.1) | 159(55.8) | 171(63.3) | 38(66.7) | 0.253 |
| Comorbidities | 414(67.6) | 165(57.9) | 205(75.9) | 44(77.2) | <0.001 |
| Family history of respiratory diseases# | 115(18.8) | 39(13.7) | 57(21.1) | 19(33.3) | 0.007 |
| Respiratory symptom | 375(61.3) | 139(48.8) | 187(69.3) | 49(86.0) | <0.001 |
| mMRC score※ | 0.47±0.73 | 0.27±0.60 | 0.62±0.91 | 0.98±0.88 | <0.001 |
| TB, μmol/L | 11.8±4.0 | 11.9±4.2 | 11.6±3.7 | 12.2±4.0 | 0.486 |
| Lung function | |||||
| FVC, L | 3.32±0.77 | 3.71±0.72 | 3.08±0.62 | 2.56±0.62 | <0.001 |
| FVCpred,% | 103.7±19.8 | 117.1±16.0 | 95.5±12.4 | 76.4±15.8 | <0.001 |
| FEV1, L | 1.96±0.59 | 2.37±0.47 | 1.71±0.35 | 1.04±0.23 | <0.001 |
| FEV1pred,% | 77.2±20.2 | 94.2±11.5 | 67.1±8.3 | 39.9±7.8 | <0.001 |
| FEV1/FVC,% | 58.6±9.4 | 64.2±4.6 | 56.3±8.2 | 41.4±7.2 | <0.001 |
| Follow-up duration, yr | 1.8±1.9 | 2.0±2.1 | 1.6±1.6 | 2.0±2.2 | 0.095 |
Notes: Data are presented as the n (%) for or the mean ± SD. Characteristics of participants among GOLD 1, GOLD 2 and GOLD 3–4 compared using One-Way analysis of variance (ANOVA) test for continuous variables and the χ2 or Fisher exact test for categorical variables. ※There is one subject excluded in the analysis of smoking status, occupational exposure and mMRC score variables respectively due to missing values of interest. #Means that seven people were excluded for unknown family history of respiratory diseases. Pack-yrs is a unit of smoking index. It indicates multiplying the number of packs of cigarettes smoked per day by the number of years the person smoked. P values marked bold indicate that the value is statistically significant. BMI was calculated by dividing the weight in kilograms by the square of height in meters (kg/m2).
Abbreviations: GOLD, the Global Initiative for Chronic Lung Disease; mMRC, modified Medical Research Council dyspnea; BMI, Body Mass Index; TB, Total Bilirubin; %, percent; FVC, Forced vital capacity; FVC, % predicted, the ratio of FVC to its predicted value; FEV1, Forced expiratory volume in the first second; FEV1%predicted, the ratio of FEV1 to its predicted value; FEV1/FVC, the ratio of FEV1 to FVC.