Potential Application of Anti-Cyclic Citrullinated Peptide (Anti-CCP) for the Diagnosis of Periodontal Disease in Patients with Rheumatoid Arthritis with Cut-Off Determination

Background: Rheumatoid arthritis (RA) and periodontal disease (PD) are both characterized by an inflammatory reaction. Anti-cyclic citrullinated peptide (anti-CCP) is a common diagnostic test for RA. Anti-CCP is proposed to be used as a serological biomarker to detect PD in patients with RA. Methods: A case-control study was designed for 94 subjects; 42 patients with RA and 52 without RA. PD and its types were investigated among these subjects. An enzyme-linked immunosorbent assay (ELISA) test was used to measure anti-CCP levels in these subjects. Results: Subjects were recategorized into four groups after PD diagnosis: group 1 for RA with PD (34.04%); group 2 for RA only (10.63%); group 3 for PD only (30.85%); and group 4 for individuals without RA and PD (24.46%). Anti-CCP may be considered an effective biomarker for predicting the development of PD in RA patients based on five current results found in group 1 compared to other groups. These included the detection of significantly higher anti-CCP levels, a high sensitivity (63.15%), low specificity (50%), higher cut-off value (58.53 U/ml), high positive predictive value (94.73%), and low negative predictive value (8.69%) of anti-CCP. Chronic periodontitis is the most common and has a significant association with elevated levels of anti-CCP. Conclusion: Measuring the anti-CCP level in RA patients may be a good indicator for PD diagnosis based on the suggested cut-off value. The sensitivity of the test is sufficiently reliable to produce true positive results. Anti-CCP may also be useful in the diagnosis of PD type, especially chronic periodontitis.