Fig. 6

Forest plot of the subgroup analysis for the primary outcome. A post hoc subgroup analysis was performed based on gender, smoking status, oral frailty, and age. To evaluate the effect of the intervention within each specific subgroup, the results were presented separately as relative risks (RRs) with 95% confidence intervals (CIs). The interaction term is a test of whether the effect of the experimental intervention is statistically different in significance between subgroups.