Table 1.
Baseline Characteristics of Participants Who Survived and Those Who Died Over the Five-Year Study Period
| Total sample ( = 611) | Survivors ( = 445) | Non-survivors ( = 166) | value* | |
|---|---|---|---|---|
| Mean age (SD), yr | 67.2 (8.4) | 65.5 (8.6) | 70.1 (7.0) | <0.001 |
| Mean pack/years smoked (SD) | 47.7 (28.7) | 44.9 (27.9) | 55.6 (29.4) | <0.001 |
| Mean BMI (SD) | 27.8 (4.3) | 27.9 (4.3) | 27.5 (4.3) | 0.28 |
| Mean FEV1 (SD), L | 1.37 (0.46) | 1.45 (0.46) | 1.13 (0.38) | <0.001 |
| Mean percent predicted FEV1 (SD), % | 49.7 (14.6) | 52 (14) | 43.6 (14) | <0.001 |
| Mean FEV1/VC (SD), % | 50 (10.3) | 51.1 (10.2) | 47.3 (10.1) | <0.001 |
| Current smokers, (%) | 130 (21) | 101 (23) | 29 (18) | 0.26 |
| Level of dyspnea, (%)† | <0.001 | |||
| 1 | 44 (7) | 43 (10) | 1 (1) | |
| 2 | 306 (50) | 243 (55) | 63 (38) | |
| 3 | 233 (38) | 147 (33) | 86 (52) | |
| 4–5 | 28 (4) | 12 (3) | 16 (10) | |
| Mean VAS dyspnea, (SD) | 49.5 (20.5) | 44.8 (20.5) | 54.3 (20.5) | <0.001 |
| COPD severity, (%) | <0.001 | |||
| GOLD stage I | 304 (50) | 249 (56) | 55 (33) | |
| GOLD stage II | 267 (44) | 182 (41) | 85 (51) | |
| GOLD stage III–IV | 40 (6) | 14 (3) | 26(16) | |
| Previous hospitalizations‡, (%) | <0.001 | |||
| 0 | 387 (63) | 309 (69) | 78 (47) | |
| 1 | 131 (21) | 91 (20) | 40 (24) | |
| 2 | 46 (8) | 24 (5) | 22 (13) | |
| 3 or more | 47 (8) | 21 (5) | 26 (16) | |
| Previous emergency department visits‡, (%) | 0.99 | |||
| 0 | 480 (79) | 349 (78) | 131 (79) | |
| 1 | 79 (13) | 58 (13) | 21 (13) | |
| 2 or more | 52 (8) | 38 (8) | 14 (8) | |
| Mean number of comorbidities (SD) § | 1.6 (1.2) | 1.6 (1.2) | 1.5 (1.2) | 0.37 |
FEV1 indicates forced expiratory volume in the first second; VC indicates vital capacity; BMI indicates body mass index; VAS indicates visual analogue scale and GOLD indicates Global Initiative for Chronic Obstructive Lung Disease
* p-values refer to the comparison between survivors and non-survivors and are based on Student’s t-test and Wilcoxon test for continuous variables and Chi-square and Fisher’s exact tests for categorical variables
† Dyspnea was assessed using a modification of the Fletcher scale,13 where 1 = dyspnea only with intense and strenuous exercise, 2 = capable of walking at the same pace as other people of my age on the level, 3 = capable of walking on the level at my own speed without dyspnea, but incapable of walking at the same pace as persons of my own age, 4 = dyspnea after walking slowly for 100 meters, and 5 = dyspnea when resting or after slight effort such as getting dressed. Because of small numbers in level 4 and 5, these levels were collapsed to create four categories. VAS dyspnea values from 0 to 100 points, the greater the value, the worse the dyspnea
‡ Over the prior two years
§ Comorbidity was assessed as mean number of co morbidities/patient