The Stack Overflow podcast is back! Listen to an interview with our new CEO.

Questions tagged [cox-model]

Cox proportional hazards regression is a semi-parametric method for survival analysis. No distributional form needs to be assumed, only that the effect of one-unit increase in a covariate is a constant multiple.

Filter by
Sorted by
Tagged with
1
vote
0answers
18 views
1
vote
2answers
49 views

Expressing a hazard function with a Cox proportional hazards model

I'm trying to wrap my head around Cox models as well as how to express them in the form of hazard functions when you have both categorical AND numeric covariates. I need some assistance with this ...
1
vote
0answers
145 views

Including a baseline risk for each participant to consider having a different number of data points in Cox model

We used the Cox model to associate environmental exposures with time to heart failure using cohort data. The following question has been raised: When using the extended Cox model, did you include a ...
0
votes
0answers
2 views

Attrition from HIV Care And Predictors Of Attrition From Care Among HIV Infected Adults Receiving ART,this my research problem [closed]

can i conduct/estimate/ an incidence rate in case control study and also is it possible to analysis survival from case control study?..as my knowledge incidence rate will be best ok with cohort study,,...
0
votes
0answers
18 views

How to better understand when to use Weibull AFT versus Cox Model for Failure Data

I am struggling to understand when I should consider using a Cox regression model versus using a Weibull AFT model to predict the end of life of mechanical components. I have tried to apply the Cox ...
0
votes
0answers
15 views

How to obtain predicted time to event using survival analysis?

I have a dataset with right censored data and I have fitted a cox regression model on it but I realised that the output of the model is a hazard rate rather than a prediction of time to event. I have ...
0
votes
0answers
9 views

log values in coxph model?

I have a data frame of gene expression values (sequencing). When I do CPM-normalization without doing log2, I get much "better" (lower) p-values compared to when I do log2-CPM. What is the ...
0
votes
1answer
25 views

Attirbutable risk from competing risks

There are a number of ways to estimate attributable risk fractions from Cox regression and logistic regression. Does anyone know how to estimate attributable risk from a competing risks regression ...
3
votes
0answers
34 views

proportional hazards model with fixed interval censoring = cloglog GLM with fixed effect of time?

Consider a survival analysis with time-constant coefficients, interval-censored, where the observation intervals are consistent across all individuals (e.g. each individual is observed at the end of ...
1
vote
1answer
35 views

What does the output of a Cox Proportional Hazard model mean?

For a linear regression plugging different X values to the fitted model gives us the different predicted Y values, for a logistic regression we get the different log odds: what does the output of the ...
0
votes
1answer
22 views

Multiple cox regression with no events in one group of one variable — survival analysis

I am trying to run a multivariate Cox regression analysis but I have 1 value for 1 variable that has no events reached. This variable was treatment (values = treatment 1, treatment 2, treatment 3, and ...
0
votes
0answers
11 views

Simulate recurrent events data where last observation is censored

I would like to simulate a recurrent events dataset for survival analysis with cox regression in R. The data should have the following properties: multiple, varying number of observations per ID only ...
0
votes
0answers
11 views

Cox regression and penalised spline

I am doing a time-to-event investigation and am using a Cox proportional hazards regression model. It is the first time I have worked with this technique. The time-to-event is the number of trials a ...
0
votes
3answers
35 views

Dealing/Interpretating confounding variables in cox regression (time-varying covariates using counting process notation)

I have 3 predictors which are correlated by approx. 0.57. One measures the intensity of a task. One measures the success (profitability above x) of a task and one the failure of a task (profitability ...
2
votes
0answers
30 views

'pspline ' or 'rms' in a Cox model?

I am quite new in the spline subject and I have a question! I am using a Cox model and I was afraid that some of the variables included in the model have a non-linear effect on survival. So I tested ...
2
votes
1answer
71 views

Interpret survival curve for multiple-event Cox proportional hazard model

I am using the bladder2 dataset, which is setup in "conditional" long format: ...
0
votes
1answer
54 views

Distribution of the partial likelihood ratio test in Cox model?

If I replace the partial likelihood of the Cox model https://en.wikipedia.org/wiki/Proportional_hazards_model#The_Cox_model instead of the likelihood in the likelihood ratio test https://en....
0
votes
0answers
12 views

Is this weird pattern in my Martingale Residuals plot normal?

I'm running a cox model: coxtest<-coxph(Surv(time=Age_Sample,time2=Age_event,event=LungCancer)~Cigarettes_Lifetime,data=mydata) Then I do ...
1
vote
0answers
52 views

Propensity Score Matching with Cox Regression

I am conducting a survival analysis with a Cox regression whereby the outcome variable (promotion to a senior role) is either 0 or 1. I am particulalry interested in the hazard rate (i.e., the 'hazard'...
1
vote
1answer
60 views

Assessing Continuous Predictor with HR in Cox Model

I would like to recreate the following figure The authors state this about the figure: "Multivariate Cox regression models witha cubic natural spline analysis were used to determine the potential ...
1
vote
0answers
18 views

Hazard ratio endpoint vs Odds ratio

This study (https://academic.oup.com/cid/article/65/1/100/3097834) seems to conduct a cox proportional hazard regression on survival data, but reports hazard ratios for 30- and 90-day mortality: ...
1
vote
0answers
66 views

Restricted Mean Survival Time vs Hazard Ratio - How to describe the differences?

I came across this article which discusses some modifications to a traditional clinical trial monitoring setting where a time-to-event outcome is described in terms of the restricted mean survival ...
0
votes
1answer
30 views

Transformations in a Cox Model

I am standardizing all my continuous covariates (and log transforming them to minimize undue influence). However I would like to express the change in the log hazard per 10 year change for my ...
1
vote
1answer
44 views

What are the hazard ratios in this plot referring to?

With the following code in R, I created this graph: ...
0
votes
1answer
93 views

Adjusted Survival Curves Strata Specification with Continuous Predictor

I have a continuous predictor in a multivariate Cox regression. I have chosen to present the hazard ratio per standard deviation difference (and subsequently done the same for all continuous ...
0
votes
0answers
49 views

Cox Hazard analysis using unequal number of data

I'm doing a survival analysis of a temperature treatment on 3 different sexual cross types of corals. I have a data set of 628 observations with unequal number of samples (see table below). I would ...
1
vote
1answer
16 views

How can I determine the overall Cox proportional hazard HR in multivariate analysis?

I am using the survival and survminer packages in R. I use the data and code below as an example. See also the output below. I ...
0
votes
0answers
17 views

Appropriate censoring and truncation for customer survival analysis

I am working on a regular customer survival analysis problem. Here I analyze customers who signed up between 2015-1-1 & 2018-1-1. Customers can register anytime during this interval and exit ...
1
vote
0answers
42 views

How can I determine whether my Cox regression analysis have enough power to conclude an outcome

I have 159 tumor patients, of which I know several parameters: age, sex, stage, ... and x. X is a continuous covariate corresponding to the percentage of tumor cells currently dividing (biological ...
1
vote
1answer
95 views

Schoenfeld test (cox.zph) shows no covariate violates PH assumption but global test suggests whole model does (p<0.001). What to do?

Using cox.zph (part of the survival package), I find that no covariate violates the PH assumption in a Cox regression model (p > ...
0
votes
0answers
129 views

Adjust for confounder in calculating explained variability in cox-regression

My question is closely related to this one. I am interested in the proportion of variability which is explained by a certain covariate X in a cox-model. So I have the cox-model “outcome ~ X”, for ...
0
votes
1answer
26 views

Set new reference level for hazard ratios

I run a Cox Regression and afterwards, I predicted the Hazard Ratio (HR) for the predictor values 1 to 10. My data looks something like this: ...
1
vote
0answers
31 views

time-varying coefficients (Cox regression) - interaction terms

I'm fitting a cox regression model that violates the proportionality assumption by breaking the data into three intervals as suggested by Therneau et al. p. 17~ (https://cran.r-project.org/web/...
1
vote
0answers
28 views

Cox regression with numerous interaction terms

I am fitting a Cox regression model using the coxph() function of the survival package in R. I have 15 predictors. One of the predictors is treatment (given / not given). The treatment is a well-...
0
votes
0answers
16 views

Survival Analysis - Describing Results from KM to Cox

I am familiar with the basics of survival analysis although I am stuck in organizing my figures for presentation. I constructed an adjusted KM curve and stratified my covariate of interest by the ...
0
votes
1answer
54 views

How to Illustrate Results from Cox model with Covariates

I have a data set for which I have fit a Cox proportional hazards model. For publication, I'd like to plot a graphical representation (perhaps a cumulative incidence) curve. My variable of interest is ...
1
vote
0answers
12 views

Results of a survival analysis change when converting the data to counting process format

Consider the following simple example: ...
0
votes
1answer
19 views

Is it appropriate to adjust a Cox regression model for the baseline year when using data from open cohorts?

I was wondering whether it is correct to include baseline year as additional covariate in a Cox regression model when using data from an open cohort. I will try to give an example to make this clearer:...
0
votes
0answers
12 views

Cox Proportional Hazard calibration with same it's meant to predict

I want to model time to churn with a Cox Proportional Hazard model and use it to predict people likely to churn. The question I have is how valid is to calibrate the model with the same people I want ...
2
votes
0answers
35 views

p trend for Hazard Ratios of a categorical independent variable

I ran an analysis using a Proportional Hazards Cox regression model. My variable of interest is exposure to pesticides (kg of pesticides applied within 500m of home). We do not expect a linear ...
0
votes
0answers
15 views

Death-cases only in Cox PH?

I am using a dataset with 1078 patients who received an ankle replacement. In ca 100 patients (Event=2) the implant had to be exchanged after an interval of 3-12 years. There are 7 possible reasons ...
1
vote
1answer
37 views

Conducting a subgroup analysis with regression modeling

I'm conducting a survival analysis using Cox Proportional Hazards regression to identify prognostic factors for cancer patients. My covariates include information such as age, sex, tumor location etc. ...
0
votes
0answers
18 views

Adjusted Survival Curves Index of Variability

I am implementing the ggadjustedcurves() function in survminerpackage to create adjusted survival curves as presented in this ...
0
votes
0answers
21 views

Prediction of survival time using cox regression in R

I'm aware that we can get survival function and probability in R but is there a way to predict survival time given it is Cox regression
0
votes
1answer
34 views

Cox proportional hazards model understanding

Assuming that we perform a Cox regression as presented in the example here. I am wondering what we should expect in the output of the Cox regression if, for example, we perform the fit again but this ...
0
votes
1answer
30 views

how to cut/group variables in Cox model

Considering that for a logistic regression one approach is to cut the numeric variables (or group the categorical ones) with some algorithm before running the logistic model (to allow the algorithm to ...
1
vote
1answer
67 views

Number of Covariates in Cox PH Model and Overfitting

I have a small time to event dataset (N=20) where patients are given one of two drugs (drug) at varying doses (...
0
votes
0answers
9 views

Cox regression: Estimate the value of covariate which gives a survival probability of 50 % at a specific time point

I have a data set of 150 individuals where 30 experience the event, all at different time points. I've fitted a cox regression model using step-wise backward selection and the model came out with one ...
0
votes
0answers
67 views

Recurrent Survival Analysis with Time Dependent Covariates

I am analyzing the time (since 2000) of a policy adoption using R. These policies can be updated and so I think a recurrent Prentice Williams Peterson (PWP) model is appropriate. The challenge is that ...
1
vote
0answers
28 views

How is a survival model with constant baseline hazard and time varying covariates called?

The data situation: Supose in different forests data have been collected. These data include the temperature at different time points, the hours of rain, the type of forest and whether the event (a ...