Table 3.
Clinical, radiographic, and physiologic characteristics according to GAP stage.
| GAP stage I (n = 536) | GAP stage II (n = 268) | GAP stage III (n = 28) | P-value | |
|---|---|---|---|---|
| Age | 63.6 ± 9.1 | 71.4 ± 7.4 | 71.8 ± 4.5 | <0.001 |
| Gender (F:M) | 194 (36.2): 342 (63.8) | 38 (14.2): 230 (85.8) | 1 (3.6): 27 (96.4) | <0.001 |
| Pulmonary function test | ||||
| FVC (%) | 83.0 ± 17.2 | 68.8 ± 16.0 | 55.9 ± 12.6 | <0.001 |
| FEV1 (%) | 92.6 ± 19.1 | 81.0 ± 17.8 | 64.4 ± 13.6 | <0.001 |
| TLC (%) | 86.6 ± 19.2 | 77.9 ± 18.1 | 69.9 ± 25.8 | <0.001 |
| DLCO (%) | 69.8 ± 18.9 | 54.3 ± 20.6 | 30.2 ± 11.4 | <0.001 |
| Resting PaO2 mm Hg | 86.5 ± 21.7 | 77.3 ± 20.9 | 71.2 ± 12.6 | <0.001 |
| Resting PaCO2 mm Hg | 38.3 ± 7.7 | 35.8 ± 7.0 | 36.1 ± 6.9 | 0.002 |
| Radiologic finding | ||||
| Reticular pattern | 353 (69.2) | 162 (67.2) | 14 (58.3) | 0.490 |
| Honeycombing change | 372 (73.8) | 206 (81.7) | 22 (81.5) | 0.043 |
| Ground glass opacities | 331 (65.3) | 136 (59.1) | 18 (81.8) | 0.056 |
| Nodular lesions | 116 (24.1) | 43 (20.5) | 5 (23.8) | 0.577 |
| CPI | 33.2 ± 13.5 | 46.8 ± 13.4 | 63.7 ± 7.4 | <0.001 |
| Death (%) | 139 (25.9) | 118 (44.0) | 16 (57.1) | <0.001 |
‡The following post hoc comparisons were significant at the P = 0.05 level; all other comparisons were non-significant: GAP stage I versus GAP stage II, and GAP stage III (age); GAP stage I versus GAP stage II and GAP stage III, and GAP stage II versus GAP stage III (FVC [%]); GAP stage I versus GAP stage II and GAP stage III, and GAP stage II versus GAP stage III (FEV1 [%]); GAP stage I versus GAP stage II and GAP stage III (TLC [%]); GAP stage I versus GAP stage II and GAP stage III, and GAP stage II versus GAP stage III (DLCO [%]); GAP stage I versus GAP stage II, and GAP stage III (PaO2); GAP stage I versus GAP stage II (PaCO2); GAP stage I versus GAP stage II and GAP stage III, and GAP stage II versus GAP stage III (CPI).
CPI = 91.0 − (0.65 * DLCO [%]) − (0.53 * FVC [%]) + (0.34 * FEV1 [%]).
CPI, composite physiologic score; CRP, C-reactive protein; FEV1 = forced expiratory volume; FVC = forced vital capacity; TLC = total lung capacity; DLCO = diffusing capacity of the lung for carbon monoxide; GAP, (G, 0–1 point), age (A, 0–2 points), and 2 lung physiology variables (P, FVC and DLCO); PaO2 = arterial oxygen tension; PaCO2 = arterial carbon dioxide tension.