Table 1. Spirometric and lung volume variables in 170 subjects stratified by airflow limitation severity.
| Variable | COPD Classification | ||||
|---|---|---|---|---|---|
| GOLD 1 (n = 44) | GOLD 2 (n = 54) | GOLD 3 (n = 34) | GOLD 4 (n = 38) | All Patients (n = 170) | |
| FEV1%pred | 94.4 ± 10.5 | 63.4 ± 7.4* | 39.8 ± 5.9*,# | 26.0 ± 3.1*,#,$ | 58.4 ± 26.6 |
| FEV1/FVC (%) | 63.5 ± 5.6 | 54.8 ± 9.3* | 42.9 ± 7.6*,# | 34.5 ± 6.1*,#,$ | 50.1 ± 13.1 |
| PEF%pred | 80.7 ± 21.4 | 52.4 ± 14.6* | 37.1 ± 11.0*,# | 24.3 ± 5.6*,#,$ | 50.4 ± 25.4 |
| MMEF%pred | 38.0 ± 9.9 | 22.4 ± 6.8* | 14.4 ± 14.0*,# | 7.3 ± 1.5*,#,$ | 21.4 ± 14.3 |
| TLCpleth%pred | 111.4 ± 15.2 | 119.3 ± 23.4* | 125.5 ± 12.0* | 132.9 ± 15.5*,# | 121.5 ± 19.3 |
| RVpleth% | 127.8 ± 36.8 | 159.8 ± 55.4* | 188.3 ± 50.5*,# | 227.6 ± 58.6*,#,$ | 172.4 ± 62.2 |
| RV/TLCpleth (%) | 48.8 ± 15.3 | 55.1 ± 10.1* | 63.7 ± 8.2*,# | 71.3 ± 7.0*,#,$ | 58.8 ± 13.6 |
| ΔTLC%pred | 16.7 ± 11.2 | 32.1 ± 19.9* | 50.8 ± 16.0*,# | 58.8 ± 16.5*,#,$ | 37.8 ± 22.9 |
| ΔRV%pred | 38.1 ± 33.2 | 59.1 ± 50.5* | 98.9 ± 45.7*,# | 122.0 ± 47.0*,#,$ | 75.7 ± 55.0 |
| ΔRV/TLC (%) | 7.0 ± 18.7 | 8.2 ± 8.6 | 16.3 ± 7.5*,# | 15.9 ± 8.3*,# | 11.2 ± 12.5 |
| DLCO%pred | 90.4 ± 15.8 | 82.8 ± 16.0* | 66.6 ± 4.5*,# | 59.2 ± 9.5*,#,$ | 76.2 ± 17.8 |
Data were described as mean ± standard deviation (SD). *p < 0.05 Compared with GOLD classification stage 1; #p < 0.05 Compared with GOLD classification stage 2; $p < 0.05 Compared with GOLD classification stage 3. FEV1, the forced expiratory volume in the first second; FVC, the forced vital capacity; PEF, peak expiratory flow; MMEF, maximal mid-expiratory flow; DLCO, single breath diffusing capacity for carbon monoxide; See Fig. 1 for expansion of other abbreviations.