Preoperative Anemia and Risk of In-hospital Postoperative Complications in Patients with Hip Fracture

Purpose: To evaluate the impact of preoperative anemia on postoperative complications after hip fracture surgery. Patients and Methods: We conducted a retrospective study including hip fracture patients at a teaching hospital between 2005 and 2022. We defined preoperative anemia as the last hemoglobin measurement level before surgery < 130 g/L for men and < 120 g/L for women. The primary outcome was a composite of in-hospital major complications, including pneumonia, respiratory failure, gastrointestinal bleeding, urinary tract infection, incision infection, deep venous thrombosis, pulmonary embolism, angina pectoris, arrhythmia, myocardial infarction, heart failure, stroke, and death. Secondary outcomes were cardiovascular events, infection, pneumonia, and death. We used multivariate negative binomial or logistic regression to evaluate the impact of anemia and its severity, categorized as mild (90-130 g/L for men, 90-120 g/L for women) or moderate-to-severe (< 90 g/L for both) anemia on outcomes. Results: Of the 3540 included patients, 1960 had preoperative anemia. 188 anemic patients experienced 324 major complications, while 63 non-anemic patients had 94 major complications. The risk of major complications was 165.3 (95% CI, 149.5-182.4) and 59.5 (95% CI, 48.9-72.3) per 1000 persons in anemic and non-anemic patients, respectively. Anemic patients were more likely to have major complications than non-anemic patients (adjusted incidence rate ratio (aIRR), 1.87; 95% CI, 1.30-2.72), which was consistent in mild (aIRR, 1.77; 95% CI, 1.22-2.59) and moderate-to-severe (aIRR, 2.97; 95% CI, 1.65-5.38) anemia. Preoperative anemia also increased the risk of cardiovascular events (aIRR, 1.96; 95% CI, 1.29-3.01), infection (aIRR, 1.68; 95% CI, 1.01-2.86), pneumonia (adjusted odds ratio (aOR), 1.91; 95% CI, 1.06-3.57), and death (aOR, 3.17; 95% CI, 1.06-11.89). Conclusion: Our findings suggest that even mild preoperative anemia is associated with major postoperative complications in hip fracture patients. This finding highlights considering preoperative anemia as a risk factor in surgical decision-making for high-risk patients.