Evaluating Dickkopf-1 as a biomarker: insights into periodontitis, rheumatoid arthritis, and their comorbidity-a systematic review and meta-analysis.

Abstract

<h4>Background</h4>Dickkopf-1 is a glycoprotein that inhibits Wingless-related integration site signaling, impairing osteoblast and osteoclast functions, leading to bone loss and systemic inflammation linked to periodontitis and rheumatoid arthritis. <i>Porphyromonas gingivalis</i> exacerbates rheumatoid arthritis through citrullination and inflammation, highlighting their bidirectional relationship. To date no meta-analysis has examined the role of Dickkopf-1 in periodontitis, rheumatoid arthritis, and their comorbidity. Therefore, we conducted this meta-analysis to investigate the association and role of Dickkopf-1 in these comorbid conditions.<h4>Methods</h4>The present study was conducted in accordance with the guidelines of Transparent Reporting of Systematic Reviews and Meta-Analyses PRISMA statement (registered at PROSPERO under the number CRD42025643227). A total of 15 studies (14 case-control and 1 cross-sectional) were selected out of 386 using databases like PubMed and Google Scholar (by BM, JM, and DP). A random-effects model evaluated Dickkopf-1 levels in serum/gingival crevicular fluid in periodontitis and rheumatoid arthritis via standardized mean difference (SMD) and 95% confidence intervals (CI). Heterogeneity and publication bias were assessed using statistical metrics, forest plots, funnel plots, Begg's test, and Egger's regression.<h4>Results</h4>A total of 386 studies were retrieved and 15 were included in the meta-analysis, encompassing 4,438 participants (2,190 cases and 2,248 controls). The pooled SMD of 2.694 (<i>p</i> = 0.02; 95% CI: 1.170-6.203) indicated a significant association of Dickkopf-1 with periodontitis and/or rheumatoid arthritis compared to healthy controls. However, Egger's test revealed a t-value of 3.05 (<i>p</i> = 0.009), indicating significant publication bias.<h4>Conclusion</h4>Elevated Dickkopf-1 levels in rheumatoid arthritis and periodontitis patients suggest its critical role in the pathogenesis of both conditions. Hence, Dickkopf-1 holds therapeutic potential for managing interconnected inflammatory and bone disorders and may serve as a biomarker for diagnosing these diseases.<h4>Systematic review registration</h4>https://www.crd.york.ac.uk/PROSPERO/search, PROSPERO CRD42025643227.