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Questions tagged [cox-regression]

The term Cox regression model (omitting proportional hazards) is sometimes used to describe the extension of the Cox model to include time-dependent factors. However, this usage is potentially ambiguous since the Cox proportional hazards model can itself be described as a regression model.

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r coxph how does it treat right censored data?

Dealing with data in Cox PH model with exclusively right censoring. My understanding from reading is that right censored data does not contribute to the analysis under Cox models - however a quick experiment shows me that they do affect the HR's and…
user2498193
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Cox Model Hazard Ratio Confidence Interval

I imputed data using MICE and ran a Cox Model using survival. Output is: > est se t df Pr(>|t|) factor(ss748)Varian 0.78109445 0.1399757 5.5802158 254.8814 6.130658e-08 …
Tom
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How to plot restricted cubic spline with hazard radio, probability of mortality, or mortality rate on y-axis?

1) How can I change the y-axis to "odds ratio", "probability of mortality", and "mortality rate" for "fit" in the following example? 2) How can I change the y-axis to "hazard ratio" for "fit2" in the following…
Gurkenhals
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R predict.cox function type expected

I am using cox model for prediction. fit <- coxph(Surv(time, status) ~ age + ph.ecog + strata(inst), lung) predict(fit,type="expected") In the predict.coxph doc, it says type expected is 'the expected number of events given the covariates and…
Yoki
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Combining Imputed Data After Cox Model

I want to impute some missing data in table, and run the Cox Model on the imputed table. I can get the imputation to run on my data, and the cox model to run on the imputed data, but I don't understand how to view the cox output from the data set,…
user1288515
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How to combine hazard ratios and confidence intervals from Cox regression analyses in R

I have performed a Cox regression analysis including four variables (sex, age and two binary explanatory variables) which all have significant associations to outcome. I have used the coxph function from the "survival" package in R: …
Daniel
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Hazard Ratio Curve - SAS

Can someone please tell me, which SAS procedure to use or any other method in SAS to draw a Hazard Ratio Curve as shown in the link…
Indunil Ruhunuhewa
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Understanding the reason for Missingness in Cox model

I ran the following Cox model and got 1526679 deleted observations, which is a large portion of my data. Call: coxph(formula = Surv(time1sec, time2sec, event) ~ gain + Buy + Lev + TP + frailty(ID), data) n= 73322, number of events= 73322 (1526679…
finstats
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Piecewise linear regression with SAS PHREG

How to implement a piecewise linear regression model in PHREG procedure of SAS? For example with one knot at X=T: Y = β_10 + β_11 . X if X ≤ T Y = β_20 + β_21 . X if X >T Given the model with the constraint of continuity: Y = β_10 + β_11 . X …
Indunil Ruhunuhewa
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External validation of a Cox model using rcorr.cens() and val.surv

I have two independent datasets one with 5421 and the other 1000 subjects. What I would like to do is validate the Cox model obtained from the main dataset (main_dat, n=5421) using the external dataset (test_dat, n=1000). However, I get an error…
Ali MN
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R time at risk for each group

I have been preparing survival analysis and cox regression in R. However, my line manager is a Stata user and wants the output displayed in a similar way as Stata would display it, e.g. # Stata code . strate . stsum, by (GROUP) stsum will output a…
Joanne Demmler
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SAS PHREG - assessing proportional hazards with delayed entry

I am using a Cox proportional hazards model (PHREG) in SAS. I have used the (t1,t2)*event specification to indicate the age at which an individual came into the risk set and the age at which s/he left as described here. I am trying to figure out how…
user1499701
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How to force R not to set a refference in ordinal data in coxph

I am modeling Cox regression and some of my independent variables are ordinal data and have trouble with the reffernce groups. By default the coxph package takes the first group in a variable as a refference group, i.e. in the vaiable female/male…
Daniel
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Making predictions from a coxph model

I am having difficulty making predictions using coxph. I wish to learn a Cox PH model on in-sample data and then use the parameters derived on out of sample data as follows: # learn IS params model.PH <- coxph(Surv(days.IS, outcome.IS) ~…
Tristan Fletcher
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Survival analysis: extensions of coxph

I am currently trying to implement the Prentice, Williams and Peterson extension of the Cox model in R on survival data but I want a parametric model and can not get it done. Is there maybe a package I am unaware of or has anyone else created a…
Jaco Schoeman
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