Neutrophil-Lymphocyte Ratio as Predictor for Acute Infection After Primary Total Joint Arthroplasty in Rheumatoid Arthritis Patients.

OBJECTIVES: Preoperative levels of certain inflammatory markers in the blood can predict acute infection after primary total joint arthroplasty in patients without inflammatory disease, but whether they can do so in patients with rheumatoid arthritis is unclear. The objectives of this study were to determine whether, with appropriate cut-off values, (1) preoperative levels of NLR predicted postoperative acute infection; and (2) preoperative plasma fibrinogen, monocyte-lymphocyte ratio, C-reactive protein or erythrocyte sedimentation rate predicted postoperative acute infection.

METHODS: We retrospectively analyzed 964 patients with rheumatoid arthritis who underwent primary total joint arthroplasty at our hospital between January 2010 and November 2020. We compared preoperative levels of inflammatory markers including neutrophil-lymphocyte ratio (NLR), monocyte-lymphocyte ratio (MLR), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), plasma fibrinogen (FIB) between patients who suffered acute infection or not within 90 days after surgery. The ability of markers to predict infection was assessed in terms of the area under receiver operating characteristic curves (AUC) based on optimal cut-off values determined from the Youden index.

RESULTS: Among the 964 patients, 27 (2.8%) experienced acute infection. Preoperative levels of individual inflammatory markers predicted infection with the following AUCs and cut-off values: NLR, 0.704 (cut-off: 2.528); MLR, 0.608 (0.2317); CRP, 0.516 (4.125 mg/L); ESR, 0.533 (66.5 mm/h); and FIB, 0.552 (3.415 g/L). The neutrophil-lymphocyte ratio showed diagnostic sensitivity of 92.6% and specificity of 43.3%, while the monocyte-lymphocyte ratio showed sensitivity of 77.8% and specificity of 46.3%.

CONCLUSION: The preoperative NLR shows some ability to predict acute infection after total joint arthroplasty in patients with rheumatoid arthritis. Monitoring this ratio, perhaps in conjunction with other markers not analyzed here, may be useful for optimizing the timing of surgery in order to minimize risk of postoperative infection.