Hemoglobin-to-RDW ratio, hemoglobin-to-monocyte ratio, and hemoglobin-to-leukocyte ratio are predictive of 14-day readmission after primary total knee arthroplasty.

Background: Total knee arthroplasty (TKA) is an effective treatment for knee osteoarthritis; however, early readmissions due to complications are common. This study assessed the ability of the hemoglobin-to-red cell distribution width ratio (HRR), hemoglobin-to-monocyte ratio (HMR), and hemoglobin-to-leukocyte ratio (HLR) to predict readmission within 14 days after TKA.

Methods: Data from the Chang Gung Medical Research Database (CGRD) from 2014 to 2022 were retrospectively analyzed. Patients ≥ 20 years old who underwent primary TKA were eligible for inclusion. Patients with incomplete data on the indices of interest or follow-up < 14 days were excluded. Patient demographic, clinical, and comorbidity data were collected. Logistic regression was utilized to determine the associations between HRR, HMR, and HLR and 14-day readmission.

Results: Data from 1,137 patients were analyzed. Multivariable analysis revealed that a higher HMR was significantly associated with lower 14-day readmission risk (adjusted OR [aOR] = 0.72, 95% confidence interval [CI]: 0.51-0.997), an HMR ≥ 2.18 (optimal cutoff value) was predictive of a significantly lower 14-day readmission risk (aOR = 0.61, 95% CI: 0.39-0.96). The composite indicator, HRR-HMR-HLR score, derived from the 3 indices assessed, was significantly associated with a lower 14-day readmission risk (score 2 vs. score 0: aOR = 0.51, 95% CI: 0.27-0.98; score 3 vs. score 0: aOR = 0.37, 95% CI: 0.17-0.82).

Conclusions: High HMR and the HRR-HMR-HLR score are independently associated with a lower 14-day readmission risk after TKA. Implementing these indices into clinical practice may enhance postoperative management.