Subject demographic and clinical characteristics by chronic obstructive pulmonary disease(COPD) diagnosis
| Non-COPD | COPD | p-value | |
| Subjects n | 529 | 215 | |
| Age yrs | 58.2±16.5 | 69.4±12.2 | <0.001 |
| Males | 385 (73) | 197 (92) | <0.001 |
| Nursing home residents | 31 (6) | 22 (10) | 0.04 |
| Admitted via emergency department | 483 (83) | 180 (84) | ns |
| Admitted to ICU | 95 (18) | 53 (25) | 0.04 |
| Mechanical ventilation needed | 56 (10) | 28 (13) | ns |
| Pre-existing comorbid conditions | |||
| Congestive heart failure | 69 (13) | 54 (25) | <0.001 |
| History of stroke | 72 (14) | 33 (15) | ns |
| Chronic liver disease | 62 (12) | 21 (10) | ns |
| History of malignancy | 43 (8) | 35 (16) | 0.002 |
| Renal insufficiency | 59 (11) | 23 (11) | ns |
| Bronchiectasis | 3 (0.6) | 3 (1.4) | ns |
| History and clinical data | |||
| Altered mental status | 54 (10) | 25 (12) | ns |
| fR >30 breaths·min-1 | 49 (10) | 30 (14) | 0.06 |
| Systolic blood pressure <90 mmHg | 10 (2) | 8 (4) | ns |
| Cardiac frequency >125 beats·min-1 | 71 (13) | 28 (13) | ns |
| Temperature <95°F or >104°F | 13 (3) | 6 (3) | ns |
| Arterial pH <7.35 | 27 (5) | 20 (9) | 0.03 |
| Arterial oxygenation saturation <90% | 104 (20) | 66 (31) | 0.001 |
| Haematocrit <30% | 50 (10) | 13 (6) | ns |
| Serum BUN >30 mg·dL-1 | 118 (22) | 41 (19) | ns |
| Serum glucose >250 mg·dL-1 | 61 (11) | 14 (6) | 0.04 |
| Serum sodium <130 mEq·L-1 | 81 (15) | 27 (13) | ns |
| Pleural effusion on chest radiograph | 132 (25) | 49 (23) | ns |
| PSI score | 87±34 | 105±32 | 0.05 |
| Corticosteroid use | 77 (15) | 83 (39) | <0.001 |
| Oral steroids | 48 (9) | 26 (12) | ns |
| Inhaled steroids | 32 (6) | 70 (33) | <0.001 |
Data are presented as mean±sd or n (%) unless otherwise stated. ICU: intensive care unit; fR: respiratory frequency; BUN: blood urea nitrogen; PSI: pneumonia severity index; ns: nonsignificant. 1 mmHg = 0.133 kPa; 1°F = 1.8°C+32.