Fig. 2

Histogram and density distribution plots of the estimated propensity scores, before and after propensity score adjustment in statin and non-statin patient groups. The left side of the figure (unadjusted) shows that the non-statin group had more density on the right side of the plot versus the statin group that had more density on the left side of the plot. After adjustment (right side of the figure), both groups displayed similar densities. The results show that the two groups became more similar when considering mutual confounders that may affect the association between the main exposure variable (statins) and survival time. The C-statistic of the propensity score model was 0.75