Table 1. Baseline clinical characteristics between COPD and control (non-COPD) groups.
| Variable | COPD (N=1,123), n (%) | Non-COPD (N=22,358), n (%) | P value |
|---|---|---|---|
| Demographics | |||
| Age (years) | <0.001 | ||
| 0–50 | 83 (7.4) | 5,205 (23.3) | |
| 51–65 | 466 (41.5) | 8,531 (38.2) | |
| 66–75 | 408 (36.3) | 6,108 (27.3) | |
| >75 | 166 (14.8) | 2,514 (11.2) | |
| Gender | 0.263 | ||
| Male | 495 (44.1) | 10,236 (45.8) | |
| Female | 628 (55.9) | 12,122 (54.2) | |
| Race | <0.001 | ||
| White | 981 (87.4) | 18,639 (83.4) | |
| Black or African American | 89 (7.9) | 1,825 (8.2) | |
| American Indian or Alaska Native | 5 (0.4) | 134 (0.6) | |
| Native Hawaiian/Pacific Islander | 9 (0.8) | 406 (1.8) | |
| Unknown/not reported | 39 (3.5) | 1,354 (6.1) | |
| BMI (kg/m2) | <0.001 | ||
| <25.00 | 218 (19.4) | 3,620 (16.2) | |
| 25.0–29.99 | 305 (27.2) | 7,308 (32.7) | |
| 30.0–34.99 | 318 (28.3) | 6,232 (27.9) | |
| ≥35.0 | 282 (25.1) | 5,198 (23.2) | |
| Co-morbidities | |||
| Diabetes | <0.001 | ||
| IDDM | 97 (8.6) | 1,277 (5.7) | |
| NIDDM | 163 (14.5) | 2,753 (12.3) | |
| No | 863 (76.8) | 18,328 (82.0) | |
| Smoker within past year | 484 (43.1) | 4,423 (19.8) | <0.001 |
| Dyspnea | <0.001 | ||
| At rest | 21 (1.9) | 39 (0.2) | |
| At moderate exertion | 342 (30.5) | 984 (4.4) | |
| No | 760 (67.7) | 21,335 (95.4) | |
| Functional status prior to surgery | 0.002 | ||
| Totally dependent | 1 (0.1) | 8 (~0) | |
| Partially dependent | 30 (2.7) | 322 (1.4) | |
| Unknown | 10 (0.9) | 119 (0.5) | |
| Independent | 1,082 (96.3) | 21,909 (98.0) | |
| Ventilator dependent | 0 (0) | 4 (~0) | 0.654 |
| CHF in 30 days before surgery | 10 (0.9) | 34 (0.2) | <0.001 |
| HTN requiring medication | 841 (74.9) | 12,703 (56.8) | <0.001 |
| Acute renal failure | 0 (0) | 1 (~0) | 0.823 |
| Pre-operative dialysis | 2 (0.2) | 32 (0.1) | 0.764 |
| Disseminated cancer | 1 (0.1) | 26 (0.1) | 0.793 |
| Open wound/wound infection | 6 (0.5) | 54 (0.2) | 0.058 |
| Chronic steroid use | 97 (8.6) | 837 (3.7) | <0.001 |
| Bleeding disorders | 27 (2.4) | 304 (1.4) | 0.004 |
| Transfusion of at least one unit of packed RBCs within 72 hours before surgery | 1 (0.1) | 17 (0.1) | 0.831 |
| History of systemic sepsis | <0.001 | ||
| Prior sepsis | 0 (0) | 4 (~0) | |
| Prior septic shock | 1 (0.1) | 0 (0) | |
| Prior SIRS | 9 (0.8) | 54 (0.2) | |
| >10% weight loss in last 6 months | 2 (0.2) | 32 (0.1) | 0.764 |
| Preoperative data | |||
| Transferred from | 0.006 | ||
| Home | 1,111 (98.9) | 22,247 (99.5) | |
| Nursing home/chronic care | 6 (0.5) | 30 (0.1) | |
| Acute care hospital-inpatient | 2 (0.2) | 44 (0.2) | |
| Outside ED | 2 (0.2) | 25 (0.1) | |
| Other/unknown | 2 (0.2) | 12 (0.1) | |
| ASA class | <0.001 | ||
| I–II | 180 (16.0) | 11,813 (52.8) | |
| >II | 943 (84.0) | 10,545 (47.2) | |
| Admission status | 0.119 | ||
| Inpatient | 1,078 (96.0) | 21,650 (96.8) | |
| Outpatient | 45 (4.0) | 708 (3.2) | |
| Quarter of admission | 0.252 | ||
| Jan–March | 241 (21.5) | 5,384 (24.1) | |
| April–June | 278 (24.8) | 5,301 (23.7) | |
| July–Sept | 294 (26.2) | 5,720 (25.6) | |
| Oct–Dec | 310 (27.6) | 5,953 (26.6) | |
| Operative data | |||
| Anesthesia type | 0.457 | ||
| General | 1,120 (99.7) | 22,266 (99.6) | |
| Other | 3 (0.3) | 92 (0.4) | |
| Number of levels fused | 0.118 | ||
| 1 level | 811 (72.2) | 16,614 (74.3) | |
| 2 level | 312 (27.8) | 5,744 (25.7) | |
| Posterior instrumentation | 783 (69.7) | 15,212 (68.0) | 0.237 |
| Total operative time (min) | 0.016 | ||
| 0–180 | 607 (54.1) | 11,265 (50.4) | |
| >180 | 516 (45.9) | 11,093 (49.6) | |
| Length of stay (days) | <0.001 | ||
| 0–3 | 667 (59.4) | 14,640 (65.5) | |
| >3 | 456 (40.6) | 7,718 (34.5) | |
COPD, chronic obstructive pulmonary disease; BMI, body mass index; CHF, congestive heart failure; HTN, hypertension; ASA, American Society of Anesthesiologists.