Table 1.
Baseline Characteristics of Enrolled Patients According to FEF25-75% z-Score
| Variables | Total | Normal FEF25-75% | Low FEF25-75%* | P-value |
|---|---|---|---|---|
| (n=307) | (n=216) | (n=91) | ||
| Male | 145 (47.2%) | 78 (36.1%) | 67 (73.6%) | <0.001 |
| Mean age (years) | 61.4±10.5 | 62.5±10.5 | 58.9±10.1 | 0.006 |
| Height (cm) | 160.7±8.7 | 161.0±9.0 | 160.2±8.0 | 0.486 |
| Weight (kg) | 62.2±9.4 | 62.6±9.7 | 61.2±8.8 | 0.231 |
| BMI (kg/m2) | 24.0±3.0 | 24.1±3.0 | 23.8±3.0 | 0.535 |
| Co-morbidity | ||||
| Hypertension | 126 (41.0%) | 87 (40.3%) | 39 (42.9%) | 0.770 |
| Diabetes | 57 (18.6%) | 39 (18.1%) | 18 (19.8%) | 0.846 |
| CHD | 26 (8.5%) | 19 (8.8%) | 7 (7.7%) | 0.926 |
| Previous CVA | 11 (3.6%) | 8 (3.7%) | 3 (3.3%) | 1.000 |
| RE, PUD or GERD | 18 (5.9%) | 11 (5.1%) | 7 (7.7%) | 0.536 |
| Depression | 15 (4.9%) | 4 (1.9%) | 11 (12.1%) | <0.001 |
| History of tuberculosis | 54 (17.6%) | 33 (15.3%) | 21 (23.1%) | 0.140 |
| Smoking status** | 0.851 | |||
| Never smoker | 197 (66.8%) | 142 (65.7%) | 55 (60.4%) | |
| Occasional smoker | 24 (8.1%) | 16 (7.4%) | 8 (8.8%) | |
| Long-term smoker | 74 (25.1%) | 50 (23.1%) | 24 (26.4%) | |
| Unknown | 12 (3.9%) | 8 (3.7%) | 4 (4.4%) |
Notes: Data are presented as mean ± standard deviation or number of patients (%). *Low FEF25-75%: FEF25-75% z-score below −0.8435 (the optimal cut-off value for predicting COPD development). **Occasional smoker: an adult who has smoked less than 20 pack-years in his or her lifetime; long term smoker: an adult who has smoked over 20 pack-years in his or her lifetime.
Abbreviations: BMI, body mass index; CHD, coronary heart disease; CVA, cerebrovascular accident; FEF, forced mid-expiratory flow; GERD, gastroesophageal reflex disease; PUD, peptic ulcer disease; RE, reflux esophagitis.