Abstract
Background
Standard preoperative protocols in total joint arthroplasty utilize the International Normalized Ratio (INR) to determine patient coagulation profiles. However, the relevance of preoperative INR values in joint arthroplasty remains controversial. Acceptable INR cutoff values for joint replacement are inconsistent, and are often based on studies of primary arthroplasty, or even non-orthopedic procedures. This analysis examined the relationship between preoperative INR values and post-operative outcomes in revision total hip arthroplasty (rTHA). Optimal cutoff INR values correlated with specific outcomes were subsequently determined.
Methods
The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) was retrospectively queried for revision total hip arthroplasty procedures performed between 2006 and 2017. Patients with a preoperative INR collected no later than 1 day prior to surgery were further stratified for analysis. INR values which correlated with specific outcomes were determined using receiver operating characteristics (ROC) curves for each outcome of interest. The optimal cutoff INR value for each outcome was then obtained using univariate and multivariate models which determined INR values that maximized both sensitivity and specificity.
Results
There were a total of 11,393 patients who underwent a revision total hip arthroplasty from 2006–2017 recorded in NSQIP. Of the 2,012 patients who met inclusion and exclusion criteria, 858 had an INR < 1.0, 931 had an INR > 1.0 to 1.25, 175 had an INR > 1.25 to 1.5, and 48 patients had an INR > 1.5. Patients with progressively higher INR values had a significantly different risk of mortality within 30 days (p=0.005), bleeding requiring transfusion (p< 0.001), sepsis (p=0.002), stroke (p<0.001), failure to wean from ventilator within 48 hours (p=0.001), readmission (p=0.01), and hospital length of stay (p< 0.001). Similar results were obtained when utilizing optimal INR cutoff values. When correcting for other factors, the following poor outcomes were significantly associated with the respective INR cutoff values (Estimate, 95% CI, p value): LOS (1.67, 1.34–2.08, p <0.001), bleeding requiring transfusion (1.65, 1.30–2.09, p<0.001), sepsis (2.15, 1.11–4.17, p 0.02), and any infection (1.82, 1.01–3.29, p 0.04).
Conclusions
INR values >1.65, >1.67, >1.82, and >2.15 were correlated with increased transfusion requirements, LOS, any infection, and sepsis respectively. Therefore, even subtherapeutic elevations in INR may predict poor outcomes following revision total joint replacement. Surgeons and perioperative medical specialists should consider more stringent INR goals when optimizing patients prior to revision arthroplasty.
Level of Evidence
Prognostic Level IV
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