Comparison of Blood Platelet Distribution Width and Neutrophil-lymphocyte Ratio in Patients with Different Grades of Knee Osteoarthritis

Objective: The aim of this study was to compare platelet distribution width (PDW) and neutrophil to lymphocyte ratio (NLR) values in mild-to-moderate and severe knee osteoarthritis (OA).

Methods: This was a retrospective study of patients with knee OA according to the Kellgren-Lawrence (KL) grading system. Of 465 patients, 231 were excluded (62 due to not meeting the inclusion criteria and 169 due to the lack of simultaneous haemogram and radiographic evaluations). Demographic characteristics and PDW and NLR values were recorded. The patients were then divided into two groups: KL grade 1-3 (mild-to-moderate OA) and KL grade 4 (severe OA).

Results: In severe knee OA patients, blood PDW (13.44 ± 2.58, p= 0.01) and NLR values (2.16 ± 0.84, p= 0.04) were elevated as compared with those in mild-to-moderate knee OA patients. Blood PDW and NLR values of ⩾ 12.5 and ⩾ 2.1, respectively, were taken as cut-offs based on a receiver operating characteristics (ROC) curve analysis. In the ROC curve analysis, blood NLR ⩾ 2.1 had 60% sensitivity and 64.8% specificity, and PDW ⩾ 12.5 had 61% sensitivity and 58% specificity in predicting severe knee OA. In a univariate analysis, age (p< 0.001), PDW ⩾ 12.5 (p= 0.029) and blood NLR ⩾ 2.1 (p= 0.030) emerged as significant predictors of the severe knee OA.

Conclusion: The results suggested that the blood PDW and NLR are novel inflammatory markers that can predict the radiographic severity of knee OA in clinical practice.