Fig. 1
A reverse J-shaped trend in Iran’s national-level age-standardized traffic accident mortality rates (2006–2022) is shown for (a) overall, (b) male, and (c) female populations. Derived from a latent class growth mixture model with one trajectory, the trend shows an initial decline (intercept: 48.13, slope: -3.67) followed by a significant upward turn (quadratic term: 0.14, p < 0.001), highlighting a concerning resurgence after years of improvement