Association and predictive value of C-reactive protein, fibrinogen and periodontal indices in periodontitis severity : a cross-sectional study

To assess associations between systemic inflammatory markers, periodontal parameters, and their combined ability to identify severe periodontitis. A total of 215 patients with Stage I-IV periodontitis were included. Periodontal parameters (PLI, GI, BI, PPD, and CAL) were recorded, and fasting blood samples were collected to measure serum CRP and plasma fibrinogen. Associations between inflammatory markers and periodontal parameters were analyzed using correlation and trend analyses. A multivariable logistic regression model was constructed to evaluate the combined predictive performance of CRP, fibrinogen, PPD, and CAL in distinguishing Stage IV from Stage III periodontitis. Among 215 patients across four periodontitis stages, age differed significantly by stage (P < 0.05), whereas gender, hypertension, and diabetes did not. PPD and CAL were strongly associated with periodontitis staging (P < 0.0001), while PI, GI, and BI showed no significant stage-related differences. Systemic inflammatory markers CRP and fibrinogen were significantly associated with periodontitis stage overall (P < 0.05). CRP correlated with PPD, CAL, and fibrinogen (P < 0.05), whereas fibrinogen was associated only with CRP. A composite model integrating CRP, fibrinogen, PPD, and CAL demonstrated good discriminatory ability for severe periodontitis (AUC = 0.885). In multivariable analysis, CRP, PPD, and CAL remained independently associated with Stage IV disease. Systemic inflammatory markers, particularly CRP, provide complementary information to established periodontal parameters. A composite model integrating CRP with PPD and CAL effectively identified severe periodontitis. Assessment of systemic inflammatory burden, especially CRP, may enhance risk stratification and support more individualized monitoring of patients with advanced periodontitis when used alongside routine clinical measures.