Evaluation of Latex rheumatoid factor versus C-reactive protein in patients with rheumatoid arthritis

Introduction: Rheumatoid arthritis is an autoimmune disease that inflames the synovial joints and has associated risks such as age, female gender, family history and lifestyle factors. Early detection is essential for management. It is performed using tests such as latex rheumatoid factor and C-reactive protein. This study aims to evaluate rheumatoid factor and C-Reactive Protein, determine the sensitivity and specificity of rheumatoid factor and Creactive protein, and determine the Kappa index of the respective tests. Methodology: It is a descriptive-quantitative design, 63 samples were analyzed and the Teco Diagnostics PCR and rheumatoid factor agglutination tests were used. The sensitivity and specificity of rheumatoid factor are considered, taking C-reactive protein as a reference test. Additionally, the agreement between both tests will be considered using the kappa index and Pearson's Chi-square. Result: The Latex rheumatoid factor showed sensitivity of 58.33 % and specificity of 98.04 %. The agreement of both tests using the Kappa index was good (0.65) and the Pearson Chisquare obtained a value of 0.00 (P < 0.05), which indicates that there is a significant relationship between both tests. Conclusions: The sensitivity and specificity of rheumatoid factor latex highlights its usefulness, although the need to consider other markers for an accurate diagnosis is highlighted. The concordance with C-reactive protein suggests that rheumatoid factor latex shows promise in identifying cases of rheumatoid arthritis.