Accuracy of CBC Derived Markers Against CRP and ESR in Detecting Active Rheumatoid Arthritis in Upper Egypt

Rheumatoid arthritis (RA) is a chronic autoimmune disease that leads to persistent synovial inflammation, joint destruction, and disability, often with extra-articular manifestations like interstitial pneumonia. It predominantly affects middle-aged individuals, especially women. Early diagnosis and accurate disease activity assessment are crucial to prevent irreversible joint damage and systemic complications (4). Clinical tools like the Disease Activity Score in 28 joints (DAS28) are commonly used to monitor RA, relying on inflammatory markers such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). However, CRP and ESR can be influenced by factors unrelated to RA, such as infections or anemia, and may not always be available or cost-effective in resource-limited settings (1). In recent years, complete blood count (CBC)-derived markers have emerged as affordable and accessible alternatives for assessing systemic inflammation. These include the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), and red cell distribution width (RDW). These indices have shown strong correlations with RA disease activity in various studies, particularly NLR and RDW, which have high sensitivity and specificity for detecting active disease (2-3). Studies in Egypt have explored the diagnostic accuracy of CBC-derived markers and composite indices like the CRP-to-albumin ratio (CAR) and albumin-to-fibrinogen ratio (AFR). These markers correlate significantly with DAS28 scores, suggesting they may be reliable indicators of RA disease activity in Egyptian patients (1-3).