MATLAB: How to calculate the 95% confidence intervals of the hazard ratio from coxphfit

confidence intervalcoxphfithazard ratioMATLAB

Hi everybody.
I am using coxphfit to compute P-values and hazard ratios for data related to clinical trials and need to be able to compute a the 2-sided 95% confidence interval of the hazard ratio.
Any help will be appreciated

Best Answer

Hi Alexander,
My name is Mau and I can confirm that there is no documentation provided to calculate the confidence intervals for the Cox Proportional Hazards Model. Upon further deliberation with my colleagues, we will consider adding the confidence interval functionality to “coxphfit” in a future release of MATLAB.
In the meantime, in order to calculate a confidence interval from the fitted Cox Proportional Hazards Model, you can follow the commands below:
% Generate Weibull data depending on predictor |X|. 
rng('default') % for reproducibility
X = 4*rand(100,1);
A = 50*exp(-0.5*X); 
B = 2;
y = wblrnd(A,B);
% Fit a Cox proportional hazards model. 
[b,logL,H,stats] = coxphfit(X,y);
% Hazard Ratio exp(b)
exp(b)
ans = 
   2.5623
% Calculate 95% confidence interval of Hazard Ratio
CI = exp(b + [-1 1]*1.96*stats.se)
CI =
  2.0030    3.2778
Feel free to respond here for further questions.
Sincerely,
Mau Coen
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