Table 1.
Baseline Characteristics of the Study Population Before and After Propensity Score Matching*
| Characteristic | Overall | Before Matching | After Matching† | ||||
|---|---|---|---|---|---|---|---|
| Study Population | Venous Second Conduit | Arterial Second Conduit | Venous Second Conduit | Arterial Second Conduit | |||
| (N=59,432) | (N=53,566) | (N=5,866) | SMD | (N=5,813) | (N=5,813) | SMD | |
| Age – yr | 66.0 ± 10.5 | 66.5 ± 10.4 | 62.0 ± 10.5 | 0.43 | 62.5 ±10.4 | 62.0 ± 10.4 | 0.05 |
| Year of surgery – yr | 2008.2 ± 1.6 | 2008.2 ± 1.6 | 2008.1 ± 1.61 | 0.06 | 2008.1 ± 1.6 | 2008.1 ± 1.6 | 0.007 |
| Male sex - no. (%) | 44933 (75.6) | 39930 (74.5) | 5003 (85.3) | 0.27 | 4897.1 (84.2) | 4960.0 (85.3) | 0.03 |
| Race - no. (%) | 0.26 | 0.09 | |||||
| Unknown | 925 (1.6) | 859 (1.6) | 66 (1.1) | 76.1 (1.3) | 66.0 (1.1) | ||
| White | 36518 (61.4) | 32328 (60.4) | 4190 (71.4) | 4161.0 (71.6) | 4161.0 (71.6) | ||
| Black | 2271 (3.8) | 2125 (4.0) | 146 (2.5) | 170.5 (2.9) | 142.0 (2.4) | ||
| Hispanic | 10461 (17.6) | 9796 (18.3) | 665 (11.3) | 655.0 (11.3) | 655.0 (11.3) | ||
| Asian | 6641 (11.2) | 6023 (11.2) | 618 (10.5) | 513.0 (8.8) | 611.0 (10.5) | ||
| Native American | 126 (0.2) | 114 (0.2) | 12 (0.2) | 11.2 (0.2) | 11.0 (0.2) | ||
| Other | 2490 (4.2) | 2321 (4.3) | 169 (2.9) | 226.2 (3.9) | 167.0 (2.9) | ||
| Height – cm | 170.5 ± 10.5 | 170.2 ± 10.5 | 173.3 ± 9.5 | 0.31 | 173.2 ± 9.7 | 173.4 ± 9.5 | 0.02 |
| Weight – kg | 84.2 ± 18.9 | 83.8 ± 18.9 | 88.3 ± 18.6 | 0.24 | 88.0 ± 18.8 | 88.3 ± 18.7 | 0.01 |
| Ejection fraction - % | 52.7 ± 13.5 | 52.4 ± 13.6 | 55.6 ± 12.1 | 0.25 | 55.6 ± 12.0 | 55.6 ± 12.0 | <0.001 |
| Creatinine - mg/dL | 1.26 ± 1.09 | 1.28 ± 1.13 | 1.08 ± 0.54 | 0.23 | 1.09 ± 0.57 | 1.08 ± 0.54 | 0.02 |
| Dialysis - no. (%) | 2244 (3.8) | 2196 (4.1) | 48 (0.8) | 0.21 | 56.2 (1.0) | 47.0 (0.8) | 0.02 |
| Diabetes mellitus - no. (%) | 26558 (44.7) | 24481 (45.7) | 2077 (35.4) | 0.21 | 2065.8 (35.5) | 2051.0 (35.3) | 0.005 |
| Hypertension - no. (%) | 51158 (86.1) | 46414 (86.6) | 4744 (80.9) | 0.16 | 4748.3 (81.7) | 4702.0 (80.9) | 0.02 |
| PVD - no. (%) | 7942 (13.4) | 7384 (13.8) | 558 (9.5) | 0.13 | 573.2 (9.9) | 554.0 (9.5) | 0.01 |
| Cerebrovascular disease - no. (%) | 7979 (13.4) | 7448 (13.9) | 531 (9.1) | 0.15 | 558.7 (9.6) | 527.0 (9.1) | 0.02 |
| Chronic lung disease - no. (%) | 0.20 | <0.001 | |||||
| None | 47094 (79.2) | 42111 (78.6) | 4983 (84.9) | 4957.0 (85.3) | 4957.0 (85.3) | ||
| Mild | 6938 (11.7) | 6346 (11.8) | 592 (10.1) | 579.0 (10.0) | 579.0 (10.0) | ||
| Moderate | 3121 (5.3) | 2936 (5.5) | 185 (3.2) | 178.0 (3.1) | 178.0 (3.1) | ||
| Severe | 2251 (3.8) | 2147 (4.0) | 104 (1.8) | 99.0 (1.7) | 99.0 (1.7) | ||
| Congestive heart failure - no. (%) | 10572 (17.8) | 9989 (18.6) | 583 (9.9) | 0.25 | 610.2 (10.5) | 575.0 (9.9) | 0.02 |
| Prior MI - no. (%) | 0.20 | <0.001 | |||||
| None | 30556 (51.4) | 27224 (50.8) | 3332 (56.8) | 3326.0 (57.2) | 3326.0 (57.2) | ||
| >21 days | 10260 (17.3) | 9250 (17.3) | 1010 (17.2) | 1001.0 (17.2) | 1001.0 (17.2) | ||
| 8 to 21 days | 2673 (4.5) | 2530 (4.7) | 143 (2.4) | 140.0 (2.4) | 140.0 (2.4) | ||
| 1 to 7 days | 13695 (23.0) | 12438 (23.2) | 1257 (21.4) | 1250.0 (21.5) | 1250.0 (21.5) | ||
| >6 hrs but <24 hrs | 1467 (2.4) | 1397 (2.6) | 70 (1.2) | 64.0 (1.1) | 64.0 (1.1) | ||
| ≤6 hrs | 690 (1.2) | 654 (1.2) | 36 (0.6) | 24.0 (0.4) | 24.0 (0.4) | ||
| Prior PCI - no. (%) | 0.06 | 0.01 | |||||
| None | 46692 (78.6) | 42001 (78.4) | 4691 (80.0) | 4663.7 (80.2) | 4653.0 (80.0) | ||
| >6 hrs | 12308 (20.7) | 11154 (20.8) | 1154 (19.7) | 1129.8 (19.4) | 1144.0 (19.7) | ||
| ≤6 hrs | 429 (0.7) | 408 (0.8) | 21 (0.4) | 19.5 (0.3) | 16.0 (0.3) | ||
| Mitral regurgitation - no. (%) | 0.15 | 0.02 | |||||
| None | 39354 (66.2) | 35367 (66.0) | 3987 (68.0) | 3940.2 (67.8) | 3952.0 (68.0) | ||
| Trivial | 6834 (11.5) | 6006 (11.2) | 828 (14.1) | 799.8 (13.8) | 820.0 (14.1) | ||
| Mild | 8042 (13.5) | 7382 (13.8) | 660 (11.3) | 681.2 (11.7) | 654.0 (11.3) | ||
| Moderate | 2573 (4.3) | 2414 (4.5) | 159 (2.7) | 169.7 (2.9) | 157.0 (2.7) | ||
| Severe | 246 (0.4) | 235 (0.4) | 11 (0.2) | 9.8 (0.2) | 11.0 (0.2) | ||
| Cardiogenic shock - no. (%) | 634 (1.1) | 616 (1.1) | 18 (0.3) | 0.10 | 22.2 (0.4) | 15.0 (0.3) | 0.02 |
| CPR - no. (%) | 259 (0.4) | 247 (0.5) | 12 (0.2) | 0.05 | 13.0 (0.2) | 10.0 (0.2) | 0.01 |
| Atrial fibrillation - no. (%) | 16803 (28.3) | 15278 (28.5) | 1525 (26.0) | 0.06 | 1533.4 (26.4) | 1513.0 (26.0) | 0.008 |
| Liver disease - no. (%) | 2934 (4.9) | 2737 (5.1) | 197 (3.4) | 0.09 | 198.8 (3.4) | 195.0 (3.4) | 0.004 |
| Cancer - no. (%) | 2116 (3.6) | 1971 (3.7) | 145 (2.5) | 0.07 | 148.2 (2.5) | 144.0 (2.5) | 0.005 |
| Osteoporosis - no. (%) | 1492 (2.5) | 1416 (2.6) | 76 (1.3) | 0.10 | 86.3 (1.5) | 76.0 (1.3) | 0.02 |
| Hip fracture - no. (%) | 229 (0.4) | 219 (0.4) | 10 (0.2) | 0.04 | 12.8 (0.2) | 10.0 (0.2) | 0.01 |
| Malnutrition - no. (%) | 1852 (3.1) | 1762 (3.3) | 90 (1.5) | 0.12 | 100.2 (1.7) | 90.0 (1.5) | 0.01 |
| Anemia - no. (%) | 27908 (47.0) | 25096 (46.9) | 2812 (47.9) | 0.02 | 2762.0 (47.5) | 2787.0 (47.9) | 0.009 |
| Hypothyroidism - no. (%) | 5574 (9.4) | 5142 (9.6) | 432 (7.4) | 0.08 | 449.9 (7.7) | 431.0 (7.4) | 0.01 |
| Asthma - no. (%) | 4079 (6.9) | 3722 (6.9) | 357 (6.1) | 0.04 | 339.5 (5.8) | 349.0 (6.0) | 0.007 |
| Dementia - no. (%) | 340 (0.6) | 328 (0.6) | 12 (0.2) | 0.06 | 17.4 (0.3) | 12.0 (0.2) | 0.02 |
| Immunosuppressed - no. (%) | 1318 (2.2) | 1228 (2.3) | 90 (1.5) | 0.06 | 95.5 (1.6) | 89.0 (1.5) | 0.009 |
| Surgical status - no. (%) | 0.19 | <0.001 | |||||
| Elective | 21641 (36.4) | 19102 (35.7) | 2539 (43.3) | 2521.0 (43.4) | 2521.0 (43.4) | ||
| Urgent | 35563 (59.8) | 32350 (60.4) | 3213 (54.8) | 3193.0 (54.9) | 3193.0 (54.9) | ||
| Emergent | 2209 (3.7) | 2096 (3.9) | 113 (1.9) | 99.0 (1.7) | 99.0 (1.7) | ||
| Emergent salvage | 17 (0.0) | 16 (0.0) | 1 (0.0) | 0 (0) | 0 (0) | ||
| Redo sternotomy - no. (%) | 89 (0.1) | 78 (0.1) | 11 (0.2) | 0.01 | 11.4 (0.2) | 11.0 (0.2) | 0.002 |
| ≥3 vessel disease - no. (%) | 48338 (81.3) | 43494 (81.2) | 4844 (82.6) | 0.04 | 4810.0 (82.7) | 4810.0 (82.7) | <0.001 |
| Surgeon volume - isolated CABG | 332 ± 178 | 334 ± 180 | 321 ± 164 | 0.07 | 325 ± 174 | 322 ± 164 | 0.02 |
*
Plus-minus valves are means +/− standard deviation. 4.1% of patients missing data for mitral regurgitation, otherwise no variable with >0.2% missingness. If any missing data present, groups were balanced on missingness for each variable. CABG, coronary artery bypass grafting; CPR, cardiopulmonary resuscitation; MI, myocardial infarction; PCI, percutaneous coronary intervention; PVD, peripheral vascular disease; SMD, standardized mean difference
†
The number of patients and proportions presented are weighted due to variable 1:k matching and for estimation of the average treatment effect on the treated. Total number matched: arterial conduit = 5,813, venous conduit = 17,930.