Serum substance P level as a marker for subclinical rheumatoid arthritis activity

Abstract

ABSTRACT Background Regular assessments of disease activity are essential to prevent the progression of rheumatoid arthritis (RA). Aim of the work This study aimed to assess the utility of serum substance P (SP) level as a marker for RA activity and to establish the value of SP level for the diagnosis of subclinical RA activity. Patients and Methods The study included three groups each 30. subject Group 1 was with minimal or no disease, group 2 had moderate to severe disease activity and group 3 was healthy controls. RA patients were assessed using a Disease Activity Score-28 (DAS28) and power Doppler ultrasonography measurement of the synovitis total score. The serum substance P levels of study groups were assessed using ELISA technique. Results Statistically significant difference in serum SP level was detected in RA patients compared to controls (p ≤ 0.001) and between different disease activity groups (p ≤ 0.001). The best cut off SP value to distinguish patients in subclinical activity active disease patients was 555.5 pg/ml. This had a diagnostic sensitivity, specificity, and accuracy of 96.7%, 80% and 88.3 %, respectively. Conclusion Serum SP can be used as an indicator of RA disease activity even in those with subclinical activity.