Table. Characteristics of Patients Receiving Combination Warfarin and Aspirin Therapy vs Warfarin Monotherapy Before and After Propensity Score Matchinga.
| Characteristic | Propensity Score Matching | |||||
|---|---|---|---|---|---|---|
| Before Matching | After Matching | |||||
| Warfarin and Aspirin (n = 2453) | Warfarin (n = 4086) | P Value | Warfarin and Aspirin (n = 1844) | Warfarin (n = 1844) | P Value | |
| Age, mean (SD), y | 70.3 (12.7) | 63.6 (16.5) | <.001 | 69.2 (13.2) | 69.6 (13.5) | .33 |
| Male sex, No. (%) | 1393 (56.8) | 1933 (47.3) | <.001 | 969 (52.5) | 969 (52.5) | >.99 |
| Weight <50 kg, No./total No. (%) | 42/2377 (1.8) | 90/3903 (2.3) | .15 | 37/1786 (2.1) | 36/1762 (2.0) | >.99 |
| Body mass index >30, No./total No. (%)b | 1093/2321 (47.1) | 1743/3750 (46.5) | .64 | 828/1744 (47.5) | 792/1687 (46.9) | .61 |
| Alcohol or drug use, No. (%) | 113 (4.6) | 190 (4.7) | .94 | 79 (4.3) | 78 (4.2) | >.99 |
| Tobacco use, No. (%) | ||||||
| Former | 888 (36.2) | 1021 (25.0) | <.001 | 583 (31.6) | 591 (32.0) | .80 |
| Current | 147 (6.0) | 358 (8.8) | <.001 | 119 (6.5) | 111 (6.0) | .64 |
| Indication, No. (%) | ||||||
| Atrial fibrillation/atrial flutter | 1629 (66.4) | 1727 (42.3) | <.001 | 1132 (61.4) | 1167 (63.3) | .20 |
| Deep vein thrombosis/pulmonary embolism | 799 (32.6) | 2321 (56.8) | <.001 | 694 (37.6) | 656 (35.6) | .16 |
| Both | 25 (1.0) | 38 (0.9) | .72 | 18 (1.0) | 21 (1.1) | .75 |
| Comorbidities, No. (%) | ||||||
| Antiphospholipid antibody syndrome | 6 (0.2) | 6 (0.1) | .38 | 4 (0.2) | 4 (0.2) | >.99 |
| Coronary artery disease | 976 (39.8) | 471 (11.5) | <.001 | 463 (25.1) | 434 (23.5) | .14 |
| Cancer | 522 (21.3) | 821 (20.1) | .25 | 399 (21.6) | 390 (21.1) | .75 |
| Congestive heart failure | 556 (22.7) | 485 (11.9) | <.001 | 336 (18.2) | 345 (18.7) | .73 |
| Chronic liver disease | 48 (2.0) | 70 (1.7) | .47 | 40 (2.2) | 39 (2.1) | >.99 |
| Chronic kidney disease | 387 (15.8) | 395 (9.7) | <.001 | 249 (13.5) | 241 (13.1) | .73 |
| Diabetes | 759 (30.9) | 819 (20.0) | <.001 | 509 (27.6) | 522 (28.3) | .65 |
| History of falls | 79 (3.2) | 116 (2.8) | .38 | 57 (3.1) | 55 (3.0) | .92 |
| Hypercoagulable state | 54 (2.2) | 137 (3.4) | .01 | 45 (2.4) | 49 (2.7) | .75 |
| Hypertension | 1888 (77.0) | 2341 (57.3) | <.001 | 1347 (73.0) | 1354 (73.4) | .81 |
| Peripheral arterial disease | 221 (9.0) | 89 (2.2) | <.001 | 87 (4.7) | 80 (4.3) | .60 |
| Previous PCI/CABG | 474 (19.3) | 174 (4.3) | <.001 | 189 (10.2) | 167 (9.1) | .17 |
| Seizure disorder | 27 (1.1) | 51 (1.2) | .59 | 23 (1.2) | 20 (1.1) | .76 |
| History of Bleeding or Thrombosis, No. (%) | ||||||
| Duration of bleeding | ||||||
| ≤30 dc | 42 (1.7) | 71 (1.7) | .94 | 35 (1.9) | 33 (1.8) | .90 |
| >30 dc | 46 (1.9) | 81 (2.0) | .76 | 39 (2.1) | 36 (2.0) | .82 |
| Diathesis | 11 (0.4) | 31 (0.8) | .13 | 11 (0.6) | 11 (0.6) | >.99 |
| History of embolism, not DVT/PE | 23 (0.9) | 22 (0.5) | .06 | 14 (0.8) | 17 (0.9) | .72 |
| Previous event | ||||||
| Cerebrovascular accident or transient ischemic attack | 352 (14.3) | 335 (8.2) | <.001 | 243 (13.2) | 245 (13.3) | .96 |
| DVT/PE | 338 (13.8) | 715 (17.5) | <.001 | 277 (15.0) | 288 (15.6) | .65 |
| Gastrointestinal bleed | 116 (4.7) | 150 (3.7) | .04 | 82 (4.4) | 84 (4.6) | .94 |
| Remote myocardial infarction, >6 mo | 339 (13.8) | 154 (3.8) | <.001 | 154 (8.4) | 144 (7.8) | .55 |
| Medications, No. (%) | ||||||
| Angiotensin-converting enzyme inhibitor and/or angiotensin receptor blocker | 1134 (46.2) | 1198 (29.3) | <.001 | 765 (41.5) | 788 (42.7) | .44 |
| Aspirin, mg | ||||||
| ≤100 | 2060 (84.0) | NA | NA | 1549 (84.0) | NA | NA |
| >100 | 393 (16.0) | NA | NA | 295 (16.0) | NA | NA |
| β-Blocker | 1566 (63.8) | 1631 (39.9) | <.001 | 1054 (57.2) | 1089 (59.1) | .21 |
| Calcium channel blocker | 641 (26.1) | 825 (20.2) | <.001 | 469 (25.4) | 477 (25.9) | .79 |
| Estrogen or progesterone | 14 (0.6) | 53 (1.3) | .01 | 13 (0.7) | 12 (0.7) | >.99 |
| Heparin, low-molecular-weight heparin, or fondaparinux | 447 (18.2) | 1076 (26.3) | <.001 | 373 (20.2) | 354 (19.2) | .46 |
| Loop diuretic | 679 (27.7) | 680 (16.6) | <.001 | 441 (23.9) | 465 (25.2) | .37 |
| Nonaspirin antiplatelet | 215 (8.8) | 98 (2.4) | <.001 | 87 (4.7) | 87 (4.7) | >.99 |
| Nonsteroidal anti-inflammatory | 107 (4.4) | 155 (3.8) | .26 | 81 (4.4) | 74 (4.0) | .63 |
| Any statin | 1550 (63.2) | 1366 (33.4) | <.001 | 1000 (54.2) | 1005 (54.5) | .87 |
| Time in therapeutic range, mean (SD), [median], %d | 62.3 (18.1) [65.1] | 61.1 (19.3) [63.5] | .01 | 62.6 (18.3) [65.3] | 62.6 (18.6) [65.6] | .71 |
| Follow-up, mean (SD) [median], mo | 23.2 (22.5) [13.5] | 20.2 (21.0) [10.4] | <.001 | 22.7 (22.2) [12.8] | 23.2 (21.9) [14.0] | .27 |
| Modified HAS-BLED score, mean (SD) [median]e | 2.4 (1.2) [2.0] | 1.8 (1.2) [2.0] | <.001 | 2.2 (1.1) [2.0] | 2.2 (1.2) [2.0] | .95 |
| Charlson Comorbidity Index score, mean (SD) [median] | 4.8 (2.0) [5.0] | 3.6 (2.1) [4.0] | <.001 | 4.5 (1.9) [4.0] | 4.5 (1.9) [4.0] | .54 |
Abbreviations: CABG, coronary artery bypass graft; DVT, deep vein thrombosis; HAS-BLED, hypertension abnormal renal/liver function stroke, bleeding history or predisposition, labile INR, elderly, drugs/alcohol concomitantly; INR, international normalized ratio; NA, not applicable; PCI, percutaneous coronary intervention; PE, pulmonary embolism; TIA, transient ischemic attack.
a
If not otherwise specified, denominator is noted at the top of the column.
b
Calculated as weight in kilograms divided by height in meters squared.
c
Indicates bleeding history as assessed at the time of warfarin therapy initiation.
d
Therapeutic range was defined as an INR between 2 and 3.
e
HAS-BLED score modified to exclude aspirin use and labile INR.