Table 2. Primary and Secondary Outcomes for Patients Undergoing Primary Total Hip or Knee Arthroplasty for a Diagnosis of Osteoarthritis Who Were Eligible to Receive the Study Drug.
| Outcomes | No./total (%) | Estimated treatment difference, % (95% CI)a | P valueb | |
|---|---|---|---|---|
| Aspirin (n = 5416) | Enoxaparin (n = 3787) | |||
| Primary outcome | ||||
| Any symptomatic venous thromboembolism within 90 d | 187/5416 (3.5) | 69/3787 (1.8) | 1.97 (0.54 to 3.41)c | .007 |
| Components of primary outcomed | ||||
| Pulmonary embolism within 90 d | 58/5416 (1.1) | 21/3787 (0.6) | 0.44 (−0.19 to 1.08) | .17 |
| Any deep venous thrombosis within 90 d | 140/5416 (2.6) | 50/3787 (1.3) | 1.61 (0.54 to 2.68) | .003 |
| Both pulmonary embolism and deep venous thrombosis within 90 d | 11/5416 (0.2) | 2/3787 (0.1) | 0.10 (−0.10 to −0.30) | .32 |
| Above-knee deep venous thrombosis within 90 de | 12/5415 (0.2) | 6/3787 (0.2) | 0.06 (−0.11 to 0.23) | .49 |
| Below-knee deep venous thrombosis within 90 d | 129/5415 (2.4) | 45/3787 (1.2) | 1.49 (0.48 to 2.50) | .004 |
| Secondary outcomes | ||||
| Death within 90 df | 4/5675 (0.1) | 2/4036 (0.1) | 0.05 (−0.05 to 0.15) | .36 |
| Major bleeding within 90 d | 17/5401 (0.3) | 15/3779 (0.4) | −0.05 (−0.35 to 0.25) | .75 |
| Readmission within 90 d | 130/5403 (2.4) | 85/3782 (2.3) | 0.6 (−0.19 to 1.39) | .13 |
| Reoperation within 90 d | 116/5412 (2.1) | 73/3787 (1.9) | 0.67 (−0.12 to 1.46) | .10 |
| Reoperation within 6 mo | 175/5086 (3.4) | 120/3535 (3.4) | 0.16 (−0.82 to 1.14) | .75 |
| Drug adherence | 521/614 (85) | 491/569 (86) | −0.99 (−0.91 to 1.08) | .85 |
a
Risk differences were calculated based on unadjusted cluster summaries.
b
All P values are for superiority.
c
The upper limit of the 95% CI (3.41%) was above the noninferiority margin of 1%; therefore, noninferiority of aspirin was not achieved.
d
Below-knee deep venous thrombosis was any thrombus distal to the popliteal vein. Above-knee deep venous thrombosis was any thrombus proximal to the popliteal vein. Pulmonary embolism was any thrombus in the pulmonary arterial tree.
e
One patient in the aspirin group with a verified deep venous thrombosis did not have a location (above or below the knee) specified.
f
Mortality data for those lost to follow-up or who opted out were determined through the National Death Index.