Association between oral health conditions and the risk of major noncommunicable diseases: A protocol for systematic review and meta-analysis

Objective: Although epidemiological studies suggest that oral health conditions may be associated with an increased risk of noncommunicable diseases, the findings have yet to be comprehensively synthesized, particularly for a major noncommunicable diseases-related health and economic burden. Therefore, we will perform a systematic review and meta-analysis of all available observational studies investigating the association between oral health conditions and subsequent risk of major noncommunicable diseases.Methods: With limited English publications, we will search electronic databases, including MEDLINE, Embase, PubMed, Cochrane Library, Scopus, and CINAHL. Based on the temporal properties and natural course of disease progression, we will seek cohort or case-control studies that investigate the association between oral disease conditions and the risk of noncommunicable diseases. Regarding the World Health Organization agenda, oral health conditions will include dental caries, periodontal disease, oral cancer, edentulism, other oral conditions (i.e., oro-dental trauma, cleft lip and palate, and noma), and endodontic lesions. Based on the global disease burden, primary outcomes of interest will include the four major systemic noncommunicable diseases: cardiovascular diseases, cancers, chronic respiratory diseases, and type 2 diabetes mellitus. Random-effects meta-analysis will be used to estimate pooled effects estimate and 95% confidence intervals. Statistical heterogeneity will be investigated using the I2 index and tau 2 statistics. Preplanned subgroup and sensitivity analyses and random-effects meta-regression analyses will be performed to address possible heterogeneity and establish the robustness of the meta-analytic estimates. The prediction intervals, expected (E)-value, and evidence certainty will be appraised to synthesize the findings and draw evidence-based conclusions.Conclusion: This systematic review will summarize all available evidence regarding the association between oral health conditions and the risk of major noncommunicable diseases. The findings will encourage collaboration between oral health and primary care professionals for early detection and management of noncommunicable diseases and promote oral health well-being.Systematic review registration: PROSPERO: CRD42021274184.