Injury-associated anemia and iron homeostasis following orthopaedic trauma: a prospective observational study of 844 patients.

Abstract

Objective: Evaluate the incidence of injury-associated anemia and functional iron deficiency following operative fracture care.

Methods: Design: Prospective cohort study.

Setting: Level 1, academic trauma center.

Patient selection criteria: All operative fracture patients who presented between April 2022 and August 2023 were screened.

Outcome measure and comparisons: Laboratory tests for anemia were performed on post-operative day one including complete blood count, serum iron, total iron binding capacity (TIBC), percent transferrin saturation (TSAT), transferrin, and ferritin levels. Values were enumerated to capture the previously unknown incidence of injury-associated anemia.

Results: 844 patients were screened following operative fracture management (mean: 52 years (SD 22), 58% male). Injury-associated anemia was present in 94.7% (median hemoglobin: 10.0 [IQR: 8.5 - 11.1]) of the 844 eligible patients; 72.5% of patients with anemia did not reach transfusion requirements (hgb <7.0). Only 33% (270/800) received an ICD-10 diagnosis code for anemia during the hospital admission. Functional iron deficiency was present in 80.9% of eligible patients, while 94.5% demonstrated derangements in body iron stores. Ferritin levels were >50 ng/mL in 89.8% of patients overall and 96.9% in patients with all other iron studies low. Patients with fractures in multiple extremities demonstrated 52% higher odds of elevated ferritin levels than patients with isolated fractures after controlling for transfusions and sex (adjusted OR 1.52, 95%CI: 1.06-2.17, p=0.02).

Conclusion: The incidence of injury-associated anemia and functional iron deficiency was exceedingly common following operative orthopaedic trauma. Ferritin was more likely to be normal or high even when all other iron values were low, indicating that iron may become sequestered and unavailable for replenishing blood cell volume. Improving documentation of perioperative anemia after trauma and directing future research to counteract both anemia and functional iron deficiency may benefit most orthopaedic trauma patients.

Level of evidence: Prognostic Level 1.