Methods: Blood and unstimulated whole saliva were collected from RA (American College of Rheumatology criteria, N=32) and OA (physician/radiologic diagnosis, N=50) patients seen in the DCVAMC Rheumatology Clinic. Patients had no systemic infections. Specimens were centrifuged to yield serum and clear saliva of gross debris, and frozen in aliquots until assayed for PCT (Kryptor method) and hsCRP (Salimetrics for saliva, nephelometry for serum). PD was assessed with the examiner (RSR) calibrated to standard PD parameters by a periodontist (JBP). Data were expressed as mean ng/ml ± SD.
Results: Serum PCT was higher in Mod/Sev PD than in No/Mild PD (Eke et al. definition, 0.069±0.033 vs. 0.049±0.013 ng/ml, t-test p=0.001). Serum hsCRP also was higher in Mod/Sev PD than in No/Mild PD (9.989±23.289 vs. 3.495±4.856, t-test p=0.039). Mod/Sev PD vs. No/Mild PD did not differ for salivary PCT (0.043±0.024 vs. 0.036±0.017, t-test p=0.262) or hsCRP (6.636±8.090 vs. 6.865±5.978, t-test p=0.912). Concentrations of PCT or hsCRP in saliva or serum did not differ between RA and OA patients.
Conclusion: These results suggest that serum PCT is superior to serum hsCRP as a potential biomarker for Mod/Sev PD in arthritis patients because hsCRP exhibited greater variability. PCT may be an important biomarker given reports showing PD associations with poor disease outcomes among arthritis patients.