Giulia Barbati wrote: > Dear Forum, > I have a question about interaction estimate in the Cox model: > why the hazard ratio of the interaction is not produced in the summary of the > model? > (Instead, the estimate of the coefficient is given in the print of the > model.)
The 'hazard ratio of the interaction' is not well defined. Decide what hazard ratio you want to estimate, then ask summary to compute that, e.g. summary(modINT, XX_PR=c(1,3), XX_DISF=2) will estimate the 3:1 XX_PR hazard ratio at XX_DISF=2 Frank Harrell > > > # Example: > > modINT <-cph( Surv(T_BASE, T_FIN,STATUS)~ NYHA + ASINI + RFP + FE_REC + > XX_PR*XX_DISF) > > print(modINT) > > > coef se(coef) z p > NYHA=2 1.254 0.584 2.15 0.031767 > ASINI 0.665 0.409 1.62 0.104247 > RFP=2 0.725 0.704 1.03 0.302578 > FE_REC=2 -1.637 0.810 -2.02 0.043331 > XX_PR 2.189 0.649 3.37 0.000748 > XX_DISF 3.233 1.000 3.23 0.001222 > XX_PR * XX_DISF -2.852 1.280 -2.23 0.025852 > > summary(modINT) > > Effects Response : Surv(T_BASE, T_FIN, STATUS) > > Factor Low High Diff. Effect S.E. Lower 0.95 Upper 0.95 > ASINI 2.0725 2.85 0.7775 0.52 0.32 -0.11 1.14 > Hazard Ratio 2.0725 2.85 0.7775 1.68 NA 0.90 3.13 > XX_PR 0.0000 1.00 1.0000 2.19 0.65 0.92 3.46 > Hazard Ratio 0.0000 1.00 1.0000 8.92 NA 2.50 31.86 > XX_DISF 0.0000 1.00 1.0000 3.23 1.00 1.27 5.19 > Hazard Ratio 0.0000 1.00 1.0000 25.35 NA 3.57 179.88 > NYHA - 2:1 1.0000 2.00 NA 1.25 0.58 0.11 2.40 > Hazard Ratio 1.0000 2.00 NA 3.50 NA 1.12 11.00 > RFP - 2:1 1.0000 2.00 NA 0.73 0.70 -0.65 2.10 > Hazard Ratio 1.0000 2.00 NA 2.07 NA 0.52 8.20 > FE_REC - 2:1 1.0000 2.00 NA -1.64 0.81 -3.23 -0.05 > Hazard Ratio 1.0000 2.00 NA 0.19 NA 0.04 0.95 > > Adjusted to: XX_PR=0 XX_DISF=0 > > > > > > ____________________________________________________________________________________ > Be a better friend, newshound, and > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- Frank E Harrell Jr Professor and Chair School of Medicine Department of Biostatistics Vanderbilt University ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
