Abstract
The purpose of this study was to examine the relationship between elevated preoperative
international normalized ratio (INR) and (1) mortality, (2) postoperative bleeding,
and (3) other postoperative complications in a national cohort of patients who underwent
revision total knee arthroplasty (rTKA). The American College of Surgeons National
Surgical Quality Improvement Program was queried for rTKA procedures conducted between
2006 and 2017. Cohorts were based on INR ranges: <1, 1 < INR ≤ 1.25, 1.25 < INR ≤ 1.5,
and >1.5. Univariate/multivariate statistics were calculated to analyze associations
between INR value and designated covariates. These statistics were additionally applied
to optimal cutoff values of INR calculated using a receiver operating characteristics
curve. The final cohort consisted of 1,676 patients. Progressively higher INR values
were associated with an increased risk of mortality within 30 days (p < 0.006), bleeding requiring transfusion (p < 0.001), sepsis (p < 0.001), return to the operating room (Odds Ratio [OR], p = 0.011), reintubation (p < 0.001), pneumonia (p < 0.001), failure to wean from mechanical ventilation ≤48 hours (p < 0.001), acute renal failure (p = 0.001), and hospital length of stay (LOS). Statistically significant associations
were similarly seen when calculated optimal INR values were used. Optimal INR turn
point was found to be associated with a significant increased risk of long LOS (optimal
INR = 1.03, OR: 1.7, 95% confidence interval [CI]: 1.33–2.18; p < 0.001) and a significant decreased risk of bleeding requiring transfusion (INR = 1.005,
OR: 0.732, 95% CI: 0.681–0.786; p < 0.001). High preoperative INR values were independently and significantly associated
with an increased risk of multiple postoperative complications. Current guidelines
for INR <1.5 should be reassessed for patients undergoing rTKA.
Keywords
international normalized ratio - revision total knee arthroplasty - postoperative
- complications - outcomes
