Defining Preoperative Anemia Thresholds for Revision Total Hip Arthroplasty

In an era of value-based medical management, anemia optimization before revision total hip arthroplasty (THA) could improve outcomes. Simulation models in orthopedic literature help define the likelihood of successful surgery based on varying thresholds of preoperative parameters. We evaluated outcomes for revision THA if patients were either approved/denied surgery based on incremental preoperative anemia thresholds.

We retrospectively reviewed consecutive revision THA patients from 2019 to 2024 at a single institution. Exclusion criteria were primary THA, no preoperative hematocrit, and incomplete 1-year follow-up. Simulated preoperative hematocrit cutoffs of 39 through 33% were used. Preoperative hematocrit above each threshold was "approved" for surgery, while below each threshold was "denied" surgery. Intraoperative transfusions, postoperative transfusions, discharge dispositions, 90-day readmissions, and complications were evaluated. Area under the curve (AUC) determined anemia thresholds needed for an event not to occur.

If the strictest 39% hematocrit threshold were used, 626 of 1,118 (56%) patients would be denied surgery, with denied patients having higher readmissions (16.9 versus 13.2%), intraoperative transfusions (45.7 versus 11.6%), postoperative transfusions (37.2 versus 14%), nonhome discharge (66 versus 35.8%), and complications (38.2 versus 24.6%) compared to approved counterparts. If the most lenient hematocrit 33% threshold were used, 271 of 1,118 (24.2%) patients would be denied surgery, with even higher readmissions (17 versus 14.8%), intraoperative transfusions (56.5 versus 22.4%), postoperative transfusions (44.3 versus 21.5%), nonhome discharge (81.9 versus 43.3%), and complications (42.4 versus 28.9%) compared to approved counterparts. A preoperative hemoglobin above 12.7 g/dL reduced the likelihood of readmission (AUC 0.548, Positive Predictive Value [PPV] 0.889), above 11.8 g/dL reduced intraoperative transfusion (AUC 0.770, PPV 0.847), above 12.0 g/dL reduced postoperative transfusion (AUC 0.713, PPV 0.853), above 11.8 g/dL reduced nonhome discharge (AUC 0.730, PPV 0.632), and above 12.0 g/dL reduced postoperative complications (AUC 0.620, PPV 0.767).

Setting preoperative anemia thresholds for revision THA eligibility may reduce the likelihood of readmissions, transfusions, complications, and nonhome discharges.