DESIGN: Observational study.
SETTING: Kusatsu, Shiga.
PARTICIPANTS: We analysed data from 510 Japanese men (aged 46-76 years) with no history of myocardial infarction.
PRIMARY AND SECONDARY OUTCOMES: Mean SpO2, minimum SpO2 and oxygen desaturation index (ODI) were measured using overnight pulse oximetry (primary exposures), while CAC was assessed using CT. Prevalence of CAC (>0) and its burden (CAC 0, >0-100, >100-400 and>400) were evaluated as outcomes. Body mass index≥25.0 kg/m2 defined as obesity.
RESULTS: Mean±SD age was 66.7±7.2 years. The prevalence of CAC was 64.7% (CAC scores>0-100, 31.4%; >100-400, 20.0% and>400, 13.3%). In multivariable binary logistic regression, the OR and 95% CI for the prevalence of CAC were 1.25 (1.02 to 1.53) per 1-SD decrement in mean SpO2 and 1.25 (1.01 to 1.55) per 1-SD increment in ODI. The associations lost their significance while further adjusted for DM and dyslipidaemia. Similar trends were observed for the level of CAC burden in multivariable ordinal logistic regression. Obesity did not show significant interaction with SpO2 on CAC. In mediation analysis, the OR (95% CI) for natural indirect effect; percentage mediated through dyslipidaemia in association of 1-SD decrement in mean SpO2 with prevalence of CAC were 1.06 (1.01 to 1.10); 25.4%. These estimates for mediation through DM and dyslipidaemia for 1-SD increment in ODI in the associations were 1.07 (1.01 to 1.12); 29.6% and 1.04 (1.00 to 1.08); 17.5%, respectively.
CONCLUSIONS: Lower mean SpO2 and higher ODI are associated with CAC among Japanese men, independent of age, lifestyle factors and obesity. The associations became non-significant after adjusting for diabetes and dyslipidaemia, but were mediated through these factors.
METHODS: The National Health and Nutrition Examination Survey (NHANES) is a population-based observational study, conducted periodically in Mexican American, Other Hispanic, Non-Hispanic (NH) White, NH Black, and other racial/ethnic participants. We linked 2009-12 survey data of 8199 adults to the mortality data until 2019. By analyzing RNA gene sequences from oral rinse samples, microbiome alpha diversity within individuals was assessed using operational taxonomic unit (OTU) richness. Potential mediators included obesity, diabetes mellitus, dyslipidemia, hypertension, and periodontitis. Multivariable Cox proportional hazards regression and causal mediation analysis were used.
RESULTS: Baseline mean ± standard deviation (SD) age was 42.1 ± 15.1 years. Over a median follow-up of 9.1 years, 405 all-cause mortality occurred (CVD, 105; non-CVD, 300). Each 1-SD increment in OTU richness was inversely associated with all-cause mortality (hazard ratio [HR] 0.92, 95 % confidence interval [CI] 0.90-0.95), CVD mortality (HR, 0.92; 95 % CI, 0.90-0.95), and non-CVD mortality (HR, 0.92; 95 % CI, 0.90-0.95). With evidence of significant racial and ethnic groups-interaction (p <0.05), these associations were evident in Mexican American, NH White, and others racial/ethnic participants. None of the potential mediators significantly mediated the associations of OTU richness with all-cause, CVD, and non-CVD mortality.
CONCLUSIONS: Lower oral microbiome alpha diversity is associated with higher risk for all-cause, CVD, and non-CVD mortality, and the associations are varied by racial and ethnic groups.