Table 1 Comparability of the groups before matching
From: Metformin therapy and postoperative atrial fibrillation in diabetic patients after cardiac surgery
Variable | Metformin prior to admission (n = 635) | Non-metformin prior to admission (n = 648) | p value |
|---|---|---|---|
Demographics | |||
 Age, years, mean (SD) | 65.1 (9.8) | 66.6 (10.1) | 0.0064 |
 Sex (male) | 448 (70.6%) | 423 (65.3%) | 0.0431 |
 Race (white) | 628 (98.9%) | 633 (97.7%) | 0.0944 |
 BMI, kg/m2, mean (SD) | 32.37 (6.0) | 32.13 (6.9) | 0.4981 |
 Alcohol use ≥ 2 drinks per week | 36 (8.8%) N = 409 | 27 (6.8%) N = 397 | 0.2900 |
Medical characteristics | |||
 Hypertension | 571 (89.9%) | 599 (92.4%) | 0.1117 |
 Dyslipidemia | 564 (89.0%) | 572 (88.3%) | 0.6985 |
 Lung disease | 133 (20.94%) | 154 (23.8%) | 0.2255 |
 Peripheral artery disease | 67 (10.6%) | 78 (12.1%) | 0.4007 |
 Prior heart failure | 28 (7.6%) N = 368 | 48 (13.6%) N = 352 | 0.0085 |
 Prior MI | 195 (33.1%) N = 590 | 234 (39.1%) N = 599 | 0.0308 |
 CKD (eGFR < 60 mL/min) | 243 (38.3%) | 371 (57.3%) | < 0.0001 |
 HbA1C ≥ 9% | 104 (18.4%) N = 566 | 79 (13.0%) N = 607 | 0.0115 |
 Mitral valve disease/stenosis | 142 (22.5%) | 169 (26.4%) | 0.1127 |
Preoperative medications use | |||
 ACE or ARB (within 48 h) | 193 (47.0%) N = 411 | 155 (38.9%) N = 399 | 0.0197 |
 ASA (within 5 days) | 555 (87.4%) | 558 (86.1%) | 0.4955 |
 Other anti-platelets | 62 (9.8%) | 58 (9.0%) | 0.6170 |
 Beta blocker (within 24 h) | 533 (83.9%) | 561 (86.6%) | 0.1827 |
 Lipid lowering agents (within 24 h) | 572 (90.1%) | 568 (87.7%) | 0.1677 |
 Steroids (within 24 h) | 19 (3.0%) | 25 (3.9%) | 0.3942 |
 Vitamin C | 117 (18.4%) | 108 (16.7%) | 0.4076 |
 Vitamin E | 19 (3.0%) | 16 (2.5%) | 0.5653 |
 Amiodarone | 47 (7.4%) | 52 (8.0%) | 0.6758 |
 Magnesium sulfate (inpatient) | 27 (4.3%) | 21 (3.2%) | 0.3399 |
Postoperative Medications Use | |||
 ACE or ARB | 254 (41.1%) | 252 (39.8%) | 0.6258 |
 ASA | 593 (96.0%) | 609 (96.1%) | 0.9265 |
 Other anti-platelets | 110 (17.8%) | 171 (27.0%) | 0.0001 |
 Beta blocker | 583 (94.3%) | 583 (92.0%) | 0.0959 |
Cardiac characteristics | |||
 Active MI (STEMI) | 15 (2.4%) | 16 (2.5%) | 0.9008 |
 CABG | 492 (77.5%) | 506 (78.1%) | 0.7940 |
 Valve surgery | 227(35.8%) | 243 (37.5%) | 0.5149 |
 Cross clamp time ≥ 120 | 72 (18.7%) N = 386 | 101 (24.4%) N = 414 | 0.0486 |
 Explant position, aortic | 1 (0.2%) | 2 (0.3%) | 0.5751 |
 Intra-aortic balloon pump | 77 (12.1%) | 95 (14.7%) | 0.1828 |
 Surgery status |  |  | 0.2790 |
  Emergent | 14 (2.2%) | 20 (3.1%) |  |
  Urgent | 257 (40.5%) | 238 (36.7%) |  |
  Elective | 364 (57.3%) | 390 (60.2%) |  |
 Resuscitation | 4 (0.7%) N = 590 | 7 (1.2%) N = 599 | 0.3769 |