Is there a relationship between blood inflammation markers and the severity of knee osteoarthritis?

Objectives: This study aims to evaluate the monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte ratio (NLR), plateletto-lymphocyte ratio (PLR), and C-reactive protein (CRP)-to-albumin ratio levels between individuals with mild to moderate knee osteoarthritis (OA) and those with severe knee OA.

Patients and methods: One hundred eighty-two participants (131 females, 51 males; mean age: 67.7±10.2 years; range, 43 to 91 years) affected by knee OA were involved in the cross-sectional retrospective study between January 2018 and January 2021. Kellgren and Lawrence (K-L) classification was performed in accordance with two-view (lateral and anteroposterior) plain radiograph examinations of each knee. The patients were grouped as follows: 98 patients had mild to moderate knee OA (K-L Grades 1-2), and 84 had severe knee OA (K-L Grades 3-4). Demographic data, neutrophil, monocyte, platelet, and lymphocyte levels, erythrocyte sedimentation rate, albumin, and CRP levels were documented. C-reactive protein-to-albumin ratio, NLR, MLR, and PLR levels were calculated.

Results: The MLR was significantly elevated in the severe knee OA group (p=0.047). A significant positive relationship was found with disease stage, MLR (r=0.206; p=0.005), and NLR levels (r=0.158; p=0.033). Receiver operating characteristic curve analyses for blood MLR demonstrated a sensitivity of 57% and specificity of 60%.

Conclusion: The study results suggest that while MLR and NLR may reflect the inflammatory response in knee OA, they are not highly diagnostic inflammatory markers that can be used to evaluate the severity or prognosis of the disease.