Fig. 2

Time-varying associations of metformin and the risk of breast cancer modified by statins

In term of the violation of PH assumption, time-varying association between metformin and the risk of breast cancer was evaluated and illustrated separately after 3 (A), 5 (B), 7 (C) and 10 years (D) of follow up. In each of them, the y-axis shows the linear predictor of the hazard function for varying values of metformin, holding statins fixed at specific cumulative years, i.e., 0 (red line), 1 (green line), 3 (blue line), 5 years (purple line). The x-axis shows the cumulative usage in years of metformin

Abbreviations: CI: confidence interval; HR: hazard ratio