CutpointsOEHR - Optimal Equal-HR Method to Find Two Cutpoints for U-Shaped Relationships in Cox Model

Use optimal equal-HR method to determine two optimal cutpoints of a continuous predictor that has a U-shaped relationship with survival outcomes based on Cox regression model. The optimal equal-HR method estimates two optimal cut-points that have approximately the same log hazard value based on Cox regression model and divides individuals into different groups according to their HR values.