The Effect of Varying Preoperative Hemoglobin Levels on the Risk of Major Complications and Surgical Site Infections After Single Level Lumbar Fusion.

Introduction: Blood transfusions are associated with an increased risk of complications after lumbar fusion, and current anemia hemoglobin thresholds are not surgery specific. We aimed to calculate single-level lumbar fusion-specific preoperative hemoglobin strata that observe the likelihood of 90-day transfusion and evaluate whether these strata are associated with increased risk of 90-day complications and 2-year infections.

Methods: A national database identified patients undergoing primary single-level lumbar fusion with preoperative hemoglobin values (g/dL). Stratum-specific likelihood ratio analysis calculated sex-based hemoglobin strata associated with the risk of 90-day transfusion. Incidence and risk of 90-day major complications and 2-year infections were observed between strata.

Results: Three female (hemoglobin strata, likelihood ratio [<10.9, 2.41; 11.0 to 12.4, 1.35; 12.5 to 17.0, 0.78]) and male (<11.9, 2.95; 12.0 to 13.4, 1.46; 13.5 to 13.9, 0.71) strata were associated with varying likelihood of 90-day blood transfusion. Increased 90-day complication risk was associated with two female strata (hemoglobin strata, relative risk [11.0 to 12.4, 1.52; <10.9, 3.40]) and one male stratum (<11.9, 2.02). Increased 2-year infection risk was associated with one female (<10.9, 3.67) and male stratum (<11.9, 2.11).

Conclusion: Stratum-specific likelihood ratio analysis established sex-based single-level lumbar fusion-specific hemoglobin strata that observe the likelihood of 90-day transfusion and the risk of 90-day major complications and 2-year infections. These thresholds are a unique addition to the literature and can assist in counseling patients on their postoperative risk profile and in preoperative patient optimization.

Level of evidence: Level III.