*3.4. Subanalysis Focusing on the Younger Group (Aged <75 Years)*

We also investigated whether the influence of CVH on incident AF was more profound in the younger group as compared with the older group (Table 3). We divided the younger group and elder group by age 75 years based on the following two reasons: (1) age 75 years was close to the median age in this study (Supplemental Figure S1) and (2) age 75 years or older was defined as advanced elderly in Japan. In participants aged <75 years, using the poor CVH group as a reference, the ideal CVH group had a significantly lower risk of incident AF (HR = 0.64, 95% confidence interval 0.46–0.88, *p* = 0.006) in model 1, adjusting for age, gender, and regular alcohol intake. Likewise, the ideal CVH group had a significantly lower risk of incident AF as compared with the poor CVH group (HR = 0.68, 95% confidence interval 0.49–0.94, *p* = 0.02) in model 2, adjusting for age, sex, history of heart disease, history of stroke, alcohol intake, and eGFR in the younger group. In model 2 in the younger group, we also observed other factors that had a significant difference: age (HR = 1.07, 95% confidence interval 1.04–1.10, *<sup>p</sup>* = 3.7 × <sup>10</sup>−6), female sex (HR = 0.42, 95% confidence interval 0.32–0.57, *<sup>p</sup>* = 5.2 × <sup>10</sup>−9), no history of heart disease (HR = 0.27, 95% confidence interval 0.20–0.35, *<sup>p</sup>* = 2.0 × <sup>10</sup>−16), no history of stroke (HR = 0.54, 95% confidence interval 0.37–0.78, *p* = 0.025), and not drinking alcohol (HR = 0.71, 95% confidence interval 0.53–0.96, *p* = 0.02).
