RCSplines

Estimating and presenting nonlinear associations and interactions with Restricted Cubic Splines (RCS)

Last updated: 2025-06-18

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• Slides for the Harvard Catalyst seminar on January 29, 2025

1. RCS to model a continuous variable in logistic and Cox regression

Supplementary material for the manuscript “Estimating and presenting nonlinear associations with Restricted Cubic Splines”, International Journal of Epidemiology 2025

• Dataset used for the examples

R material

• Code to reproduce the logistic and Cox regression examples

• Output for the examples in html format

• Functions used for the examples

SAS material

• Macros to plot ORs from a logistic model: unadjusted models / adjusted models

• Macros to plot HRs from a Cox model: unadjusted models / adjusted models

• Macros to plot predicted probabilities after logistic model: unadjusted models / adjusted models

• Macros to plot absolute risks after Cox model: unadjusted models / adjusted models

Stata material

• Code to reproduce the logistic regression example

• Code to reproduce the Cox regression example

2. RCS to model a nonlinear interaction between a binary and a continuous variable

R package interactionRCS

• Package on CRAN

• Vignette

Absolute Risks and Absolute Risk Differences from a Cox model with nonlinear interactions

• Supplemenraty material for the paper “Estimating and presenting hazard ratios and absolute risks from a Cox model with complex nonlinear interactions” published in the American Journal of Epidemiology (2024)

• R material

• SAS material

3. Generalized linear model (GLM) for estimating event risks using Pseudo-values

Pseudo-values derivation and comparison with Kaplan-Meier estimates

• SAS Macro

• ENAR 2025 Poster

Pseudo-values GLM with RCS to estimate nonlinear Absolute Risks and Absolute Risk Differences

• SAS Macro to model nonlinear effects using pseudo-values

• Macro to model nonlinear effects using Cox regression

• Simulation Example

• Simulation Data

• JSM 2023 Poster