The link of oral microbiome diversity to stroke risk: Evidence from the National Cohort Study in the United States

Objective To assess whether oral microbiome diversity and periodontal health are independently associated with stroke prevalence in a U.S. adult cohort, with implications for risk stratification in physical medicine and rehabilitation.Methods We analyzed cross-sectional data from 4,438 adults in the National Health and Nutrition Examination Survey (NHANES) 2009–2012, using survey-weighted logistic regression to evaluate associations between stroke and oral microbiome β-diversity (unweighted UniFrac), α-diversity (Shannon, Simpson), and clinical periodontal measures (probing depth, clinical attachment loss, and tooth count), adjusting for age, sex, race/ethnicity, education, income, smoking, alcohol consumption, body mass index, and diabetes.Results In crude models, each 1-mm increase in mean probing depth was associated with higher stroke odds (odds ratio [OR] = 1.89, 95% confidence interval [CI] = 1.39–2.56), as was each 1-mm increase in clinical attachment loss (OR = 1.50, 95% CI = 1.32–1.71); each additional tooth was associated with lower odds (OR = 0.91, 95% CI = 0.88–0.94). After stepwise adjustment, attachment loss (OR = 1.23, 95% CI = 1.04–1.46; P = 0.017) and tooth count (OR = 0.96, 95% CI = 0.92–0.99; P = 0.024) remained significant, whereas probing depth did not (OR = 1.30, 95% CI = 0.90–1.88; P = 0.156). A threshold effect was observed at approximately 1.46 mm for probing depth. β-Diversity clusters did not differ in stroke prevalence after adjustment (global P = 0.61), and neither α-diversity index was significant in the stepwise- or fully-adjusted models (Shannon fully-adjusted OR = 1.29, 95% CI = 0.97–1.72; P = 0.081). Periodontal associations were consistent across sex and age strata; the non-significant findings in younger participants were attributable to limited statistical power.Conclusion Clinical periodontal measures, particularly attachment loss and tooth count, were associated with stroke prevalence independently of traditional cardiovascular risk factors, whereas oral microbiome diversity indices were not. These measures may serve as readily accessible markers for refining stroke risk assessment. The cross-sectional design precludes causal inference, and findings require validation in prospective cohorts with adjudicated stroke outcomes and metagenomic profiling before clinical translation. Nevertheless, these results support integrating oral health assessment into routine stroke risk evaluation and highlight periodontal inflammation as a potentially modifiable contributor to cerebrovascular disease.