Periodontal disease and systemic autoimmune disease burden: population-based study on co-occurrence and mortality risk in the United States and the United Kingdom

To investigate the association between periodontal disease (PD) and autoimmune diseases (AIDs), and to examine the combined effect of PD and AIDs on all-cause mortality. A total of 11,739 participants aged ≥30 from National Health and Nutrition Examination Survey (NHANES 2009 - 2014), and 433,023 participants from UK Biobank (UKB) were included. PD was categorized as none, moderate, severe, or edentulous. AIDs were defined based on self-reported and laboratory-confirmed diagnoses. Poisson regression was used to examine associations between PD and AIDs, and Cox proportional hazard models were applied to estimate the separate and combined effects of PD and AIDs on mortality, adjusting for demographic, behavioural, and clinical features. Not enough evidence were found in the US population on the association between PD status and AID after fully adjusted for all covariates, but PD was found associated with AIDs in the UK population (Prevalence Ratio, PR 1.05, 95% confidence interval, CI [1.00-1.09]). Participants with AIDs alone had an increased risk of mortality compared with healthy controls (NHANES: HR [95% CI] 1.40 [1.00-1.96]); UKB: HR [95% CI]: 1.12 [1.07-1.17]). The coexistence of PD and AIDs further increased the mortality risk further (NHANES: HR [95% CI]: 1.46 [1.17-1.81]; UKB: HR [95% CI]: 1.16 [1.06-1.28]). In large US and UK population-based cohorts, AIDs are more common among individuals with PD, particularly those who were edentulous. AIDs were associated with higher mortality, and this risk was further exacerbated by the co-existing PD. This finding underscores the importance of integrating oral health assessment and periodontal care into the management of people with AIDs, as part of strategies to reduce mortality risk.