Description Usage Arguments Details Value Note Author(s) References See Also Examples
Fit a Cox model and calculate the unadjusted/adjusted attributable fraction function of a set of covariates based on the Cox model using the method proposed by Chen, Lin and Zeng (2010).
1 |
formula |
a formula object for the Cox model considered , which has the same format as that in the |
data |
a data.frame in which to interpret the variables named in
the |
cov |
the set of covariates whose attributable fraction function is of interest. |
This function calculates the unadjusted/adjusted attributable fraction function
for the set of covariates specified in cov
which must also be
included as covariates of the Cox model. The function calculates the unadjusted attributable fraction function
if the Cox model does not include other covariates; otherwise the function calculates the adjusted attributable
fraction function adjusting for other covariates in the Cox model.
time |
unique uncensored event times at which the attributable fraction function jumps. |
est |
the estimates of unadjusted/adjusted attributable fractions at unique uncensored event times. |
se |
the standard errors of the estimated attributable fractions. |
low |
the lower confidence limits of the atrtributable fractions. |
upp |
the upper confidence limits of the atrtributable fractions. |
fit.cox |
coxph object from the fitted Cox model. |
The Breslow method is used to handle ties. The function will do missing-data filter automatically.
Li Chen
Chen L, Lin DY, Zeng D. (2010). Attributable fraction functions for censored event times. Biometrika 97, 713-726.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | # simulated data set from a Cox model
n = 1000
x1 = as.numeric(runif(n)>0.5)
x2 = x1 + rnorm(n)
t = exp(-x1 - 0.5 * x2) * rexp(n, rate = 0.1)
c = runif(n, 0, 3.4)
y = pmin(t, c)
delta = as.numeric(t<=c)
test = data.frame(time=y, status=delta, x1=x1, x2=x2)
# calculate the atrributable fraction function of x1 adjusting for x2
result=paf(Surv(time, status) ~ x1 + x2, data=test, cov=c('x1'))
result$fit.cox
cbind(result$time, result$est, result$se, result$low, result$upp)[1:10, ]
# Calculate the unadjusted attributable fraciton function of x1
result=paf(Surv(time, status) ~ x1, data=test, cov=c('x1'))
|
Loading required package: survival
Call:
coxph(formula = formula, data = data, method = "breslow")
coef exp(coef) se(coef) z p
x1 1.0025 2.7251 0.1348 7.44 1e-13
x2 0.5293 1.6978 0.0596 8.89 <2e-16
Likelihood ratio test=204 on 2 df, p=0
n= 1000, number of events= 308
[,1] [,2] [,3] [,4] [,5]
[1,] 0.001101419 0.5135640 0.05308121 0.3975614 0.6072298
[2,] 0.004318428 0.5132873 0.05307189 0.3973146 0.6069438
[3,] 0.004602318 0.5130105 0.05306524 0.3970612 0.6066619
[4,] 0.004939957 0.5127333 0.05305563 0.3968146 0.6063750
[5,] 0.010080089 0.5124560 0.05304624 0.3965674 0.6060883
[6,] 0.014137511 0.5121783 0.05303695 0.3963195 0.6058014
[7,] 0.021008912 0.5118988 0.05303170 0.3960601 0.6055191
[8,] 0.021367456 0.5116186 0.05306043 0.3957176 0.6052900
[9,] 0.021669139 0.5113385 0.05309077 0.3953712 0.6050634
[10,] 0.025361345 0.5110581 0.05307931 0.3951258 0.6047703
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