DIAGNOSTIC UTILITY AND CLINICAL SIGNIFICANCE OF ANTI-CYCLIC CITRULLINATED PEPTIDE ANTIBODIES IN EARLY DETECTION OF RHEUMATOID ARTHRITIS: A HOSPITAL-BASED CROSS-SECTIONAL STUDY

Abstract

Background: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disorder characterized by progressive synovial inflammation and joint destruction. Delayed diagnosis results in irreversible joint damage, emphasizing the need for improved serological biomarkers. Traditional serological markers, such as Rheumatoid Factor (RF), lack sufficient specificity for early RA detection (1).

Objectives: To evaluate the diagnostic performance of anti-cyclic citrullinated peptide (anti-CCP) antibodies compared with RF, assess their clinical utility in seronegative RA detection, and determine whether combined testing improves diagnostic accuracy.

Methods: A cross-sectional study was conducted from June 2023 to May 2024 at a tertiary care hospital, enrolling 200 subjects (RA patients and controls) classified according to American College of Rheumatology (ACR) 1987 criteria. Serum samples were analyzed using latex agglutination for RF and enzyme-linked immunosorbent assay (ELISA) for anti-CCP antibodies. Diagnostic performance metrics including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and 95% confidence intervals (CI) were calculated for all tests.

Results: Anti-cyclic citrullinated peptide antibodies demonstrated higher specificity than rheumatoid factor while maintaining comparable sensitivity. Specificity was 98.6 percent for anti-cyclic citrullinated peptide antibodies compared with 86 percent for rheumatoid factor, whereas sensitivity was 78 percent and 76 percent respectively. Importantly, anti-cyclic citrullinated peptide antibodies were detected in half of the patients who tested negative for rheumatoid factor, thereby identifying individuals who would otherwise remain undiagnosed. When both markers were used in combination under a parallel testing strategy, overall sensitivity increased to 88 percent while preserving acceptable specificity.

Conclusions: Anti-cyclic citrullinated peptide antibodies provide greater diagnostic precision than rheumatoid factor, particularly in individuals who test negative for rheumatoid factor. Incorporation of this marker into routine diagnostic evaluation can enhance early detection and support timely therapeutic intervention. Combined serological assessment further improves detection rates and offers a comprehensive approach to the diagnosis of rheumatoid arthritis.