All Questions
Tagged with cox-model interaction
65 questions
0
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1
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33
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Setting a reference in Cox regression with splines and interaction
I run a Cox regression with a continuous variable age and a categorical variable sex. The model includes splines for the continuous variable and an interaction between both. I want to choose the ...
- 343
1
vote
1
answer
30
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Cox regression baseline risk and interpretation of coefficients
I recently encountered a problem with Cox regression that I couldn't find an answer to (please direct me to the appropriate resources if you know of any). So the problem goes as follows:
I have a ...
- 11
1
vote
1
answer
51
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Moderator Analysis in Cox Regression
Imagine an RCT with two groups with a time-to-event endpoint. The (pre-specified) strategy for analysing this trial is a Cox Regression using common covariate adjustment to reduce outcome ...
- 149
0
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1
answer
112
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Cox regression with two-way interaction and interaction p value
Hi I am using Cox regression to do some survival analysis.
I have one continous predictor variable called "biomarker" and two binary categorical variables sex and diabetes.
I want to get the ...
- 51
2
votes
1
answer
68
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Cox model: time interaction vs. covariate interactions
In the Cox model, violation of proportional hazards suggests that the effect of an exposure is not constant over time. One way this can be handled is by including time varying coefficients in order to ...
- 923
1
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1
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48
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parameterize, estimate & interprete interaction terms between two factors in a Cox Proportional Hazard model
Overview
I was trying to fit a cox proportional hazard model to look at interactions between two time-constant covariates, both of which are factors. I parameterized the model in two different but ...
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4
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1
answer
412
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Testing the proportional hazards assumption with a time varying covariate
One of the cohort studies I have carried out recently involved examining the association between post-diagnostic beta-blocker use and breast cancer outcomes in a cohort of breast cancer patients. ...
- 41
0
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0
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35
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How to realise and interprete the interaction term in Cox regression model like this?
There are two covariates: smoking history(yes or no) and gender(male or female), and the outcome is OA. The author of a paper constructed a Cox regression model with an outcome including this: smoking ...
2
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1
answer
42
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How to interpret interaction effects in a cox regression?
How would I interpret and report the highlighted boxes?
The variables:
Injury (0=uninjured, 1=injured)
Sex (0=male, 1=female)
Diet(1=10%EA, 2=50%EA, 3=100%EA, 4=150%EA, 5=200%EA)
(note: the “event” is ...
- 21
1
vote
1
answer
42
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Interpreting interactions in Cox Proportional Hazard models
I am currently doing an interactions paper with cox models to assess time to criminal recidivism as an outcome, but am struggling with the interpretations.
My two variables that are part of the ...
- 11
0
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0
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60
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p for interaction in cohort study
I have data from a cohort of 10,000 people who were followed for ten years to analyze the relationship between stress and the risk of dementia. The stress levels were independent variables, and the ...
- 49
1
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1
answer
159
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How do I interpret the interaction coefficients in a cox proportional hazards model with two factors?
I am trying to look at how two different factors A (levels A1, A2, A3, A4) and B (levels B1 and B2), as well as the interaction between the two, influence the time to an event X. As a result I am ...
- 461
1
vote
1
answer
248
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Interaction effects in a Cox model
In regression models, usually a (descriptive) indicator of an interaction effect can be plotted via a plot with x-axis with the potential interaction variable (e.g., gender) and the outcome variable ...
- 133
2
votes
2
answers
124
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Interpretation of Interaction when the results in one of the two groups is not statistically significant
Here is the question. Suppose we have a drug A, and we have conducted a RCT evaluating the risk of death in patients randomised to receive ...
- 706
0
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1
answer
184
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stratification or two-way interaction with multilevel categorical variable
I have a data with around 1600 patients from
an observational study, around 230 events. 800 have a disease, and the rest do not. My main question is the effect of therapy in a multivariable adjusted ...
- 31
2
votes
1
answer
385
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How to interpret interaction results of subgroup analysis in cox model in R
Context
I am using survival::coxph() to fit the cox model. I want to get HR for exposure factors under different sex.
I am using the dataset ...
- 121
1
vote
1
answer
167
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Is it possible to do a simple slopes analysis for a cox regression model (assuming the presence of a significant interaction)?
I have a paper in revision, in which I present a cox regression model with a significant interaction. The reviewer requests simple slopes. I am familiar with simple slopes from regular linear ...
- 23
0
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1
answer
125
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Testing for several , predefined, interactions in a Cox regression model
I want to test for several, predefined interactions with my main variable of interest in a multivariable adjusted Cox regression model.
Is there a recommended way to proceed?
Specifically, should I ...
- 1
0
votes
1
answer
317
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Cox survival PH violated variable is part of an interaction
One of my main predictors violates the PH assumption. I've been reading different ways to deal with this for a while and have decided on an interaction with time after making a person-period file (...
- 11
1
vote
1
answer
104
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interaction term in Cox PH model
I have a question with regard to interaction term in Cox PH model.
I'd like to analyze the impact of variable A on cardiovascular (CV) event.
Variable A levels are different according to sex, although ...
- 11
1
vote
1
answer
2k
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Interpretation of interaction between variable and time in cox regression
I was running a model to check the survival rate among different treatments. Basically, the treatment has four groups. I firstly plot a K-M curve and noticed clear interactions among the four ...
- 51
1
vote
1
answer
190
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Survival analysis interaction interpretation: interaction is insignificant, but pairwise comparison does hold significance
I'm new with survival analyses, and have been breaking my head over this for a while, so I hope someone can explain this in a simple manner:
Variable
HR
Gender(Female)
1.391*
Treat (Yes)
0.544***
...
- 11
0
votes
0
answers
61
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3 terms interaction in Cox PH model
'''
coxph(formula = Surv(time, hyper) ~ age + drink + smoke + sodium * tchl * BMI, data = male)
coxph(formula = Surv(time, hyper) ~ age + drink + smoke + sodium * tchl * BMI, data = female)
The 3-...
- 37
0
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1
answer
717
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About getting baseline survival probability for a piecewise Cox model with interaction term
I use Cox regression model to develop a risk prediction model for a disease and want to get a risk equation from this. The codes for that below is something like below
...
1
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1
answer
1k
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Cox regression in subgroups
I ran an analysis in which I used Cox regression to investigate the relationship between a number of predictor variables and time to death. I used R for that: ...
- 199
3
votes
2
answers
3k
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Difference in stratification, interaction and subsetting Cox Survival Regression
I'm struggling to understand the actual differences in these three approaches that came to my mind.
The problem is: I want to analyze the impact of age on mortality in my cohort. However, I want to ...
- 706
1
vote
1
answer
167
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Cox Regression Interpretation for two-covariates interaction
I am running a Cox PH model for evaluating factor associated with mortality in my dataset.
I have two covariates - one is age and one is a parameter which can vary between 0 (better) and 1 (worst).
...
- 706
0
votes
0
answers
400
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Cox Proportional Hazards Interaction Hazard Ratios
I am looking at the interaction of dose (continuous with mean=2241 and sd=949.4) and cause of death (values of 0 or 1) in a survival analysis. The interaction is tending towards significance, and ...
- 79
1
vote
1
answer
436
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Covariate and Interaction Not Significant When Both in the Model
I am looking at a survival model based on dosing variables, all of which are continuous. I have noticed when categorized, based on Kaplan Meier Curves, that low, medium, high doses behave differently, ...
- 79
3
votes
1
answer
2k
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Interpreting coefficient changes in Cox PH model involving interactions
I read the relevant questions here involving interactions in CoxPH (including 1, 2, 3, 4, 5, 6), and the relevant chapter of Applied Regression Analysis and Generalized Linear Models textbook. However,...
- 771
1
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1
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106
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If we say "Survival difference adjusted for covariates" do we mean just additive adjustment, or allow also the interactions?
Let's make it independent from any statistical package, so I will provide just numbers for the illustration. Maybe this give you some clues.
I want to compare two survival curves, for group A and B.
...
- 11
1
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1
answer
720
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How to compare hazard ratios between two levels of a categorical variable in Contrast from RMS package
I am performing an interaction spline analysis for age (continuous) and Quartiles of ancestry (categorical). My outcome variable is a survival outcome (incident stroke).
The focus is to compare Q4 to ...
- 11
2
votes
2
answers
1k
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Which method of handling non-proportional hazards (here: crossed KM curves in 2+ points) would you prefer?
I have an experiment, where I compare two groups over time in frames of the time to event analysis.
The Kaplan-Meier curves cross 3 times.
It means, that the hazards ratios switch to the opposite side ...
1
vote
1
answer
143
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Presentation of a 3x3 categorical interaction for Cox proportional hazards regression using RMS package
I wanted to verify my presentation of a 3x3 interaction of two categorical variables var1 (exposure of interest) and var2 (effect modifier of interest) using the rms...
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1
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1
answer
1k
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How to get confidence intervals for ALL cases of an interaction in the Cox model? (ideally with R)
My question is illustrated with the output of R, but the rule should be software-agnostic.
Let's assume I have this exemplary output of the coxph result in R:
...
0
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0
answers
2k
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Interaction with restricted cubic spline - comparison between SAS and R
When performing the same cox-regression in SAS and i R (including and interaction with a 3 knot restricted cubic spline), I receive different parameter estimates (i.e on age_spline 2). In my example ...
- 1
1
vote
1
answer
68
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Equivalence between interaction and second difference measures of heterogeneity
I am trying to understand a paper used by Frank Harrell in his biostats course to demonstrate how NOT to present results from an analysis of heterogeneity of treatment effects (HTE). Frank's point is ...
- 43
1
vote
1
answer
768
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Calculate Robust CI's for Stratified-Cox Regression Interaction
I have a multivariable stratified cox regression model with correction for correlation with Robust SE. There is interaction by the stratified variable, and so I would like to report adjusted Hazard ...
- 113
1
vote
0
answers
54
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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-...
- 23
4
votes
1
answer
1k
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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. ...
- 854
1
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1
answer
771
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Interaction not significant in Cox regression model?
I ran a cox model with an interaction between two categorical variables (sex and treatment group) included like:
...
- 381
0
votes
0
answers
107
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Interpreting a hazard ratio for time-dependent coefficients
I have a cox model with two main effects (x,y) and two interaction terms (xt, yt) where t is time. I am having some trouble interpreting the hazard ratios. Does the hazard ration become more of an ...
- 113
1
vote
2
answers
2k
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How to code effect modifier in a Cox Regression using R?
The definition of the distinction between the effect modifier and interaction term is:
Interaction and effect modification are formally defined within the counterfactual framework. Interaction is ...
- 605
0
votes
1
answer
405
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significant interaction between two continuous variables
I am conducting cox proportional hazard regression modelling. Two predictors in the model, for example, the age and height, have significant interaction effects on the death outcome when both using as ...
- 1
1
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0
answers
50
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Accounting for Interaction between Independent variables
Is there some trustworthy resource on effect of interactions if not accounted for.
Especially the situation is often, let's assume heart surgery, age, gender and logistic euroscore(derived from age ...
- 117
3
votes
2
answers
3k
views
Why and how does adding an interaction term affects the confidence interval of a main effect?
I was wondering why, in a regression model including an interaction term, the confidence interval of one of the main effects becomes wider.
Consider this Cox regression, where the variable IR_BMI27 ...
- 305
2
votes
0
answers
216
views
What variant of interaction when the PH assumption is violated in a CoxPH Model?
When the assumption of proportional hazards is violated, the suggestion is to interact offending covariates with time (or a function of time). In this blog post, the author suggests to include only ...
- 53
4
votes
0
answers
111
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Cox interactions and co-linearity
I am interested in developing a model to predict survival based on a few predictors: age, sex, and two lab values, albumin and globulin.
I have approximately 14,000 deaths in the data.
I initially ...
0
votes
0
answers
33
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Statistical design: retrospective analysis of effectiveness of medication
I have a retrospective dataset that has records of the medications a patient was administered to prevent recurrence of heart attack. The goal is to determine if a particular drug or combination of ...
- 493
0
votes
3
answers
808
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Difficulties fitting a Cox PH model with categorical interactions to complex survey data
I'm attempting to fit a Cox proportional hazards model to a set of NHANES data; the code to load and clean the data is here, and the resulting dataset is here.
The difficulty I'm having is ...
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