title: Compute the confidence interval of the hazard ratio of a survival regression model
body: <p>I tried to get confident interval of hazard ratio in <code>survreg()</code> function, but it's not that straightforward as coxph. </p>
  
  <pre><code>Call:
  survreg(formula = Surv(survival, DIED) ~ AGE + GENDER + PLATE + 
  NEUTRO + NIH, data = IMRAWandIST, dist = "exponential")
             Value Std. Error     z         p
  PLATE        0.00236   0.000367  6.42  1.39e-10
  EUTRO      -0.02726   0.016695 -1.63  1.03e-01
  </code></pre>
  
  <p>Scale fixed at 1 </p>
  
  <p>Exponential distribution
  Loglik(model)= -4628.6   Loglik(intercept only)= -4736.1
      Chisq= 215 on 5 degrees of freedom, p= 0 
  Number of Newton-Raphson Iterations: 5 
  n=917 (28 observations deleted due to missingness)</p>
  
  <pre><code>#estimate of beta
  a &lt;- c(coefficients(summary(fitexp)))
  
  print(coef &lt;- (a * -1 * 1 / 1)
  
  #estimate of HR
  
  print(HR &lt;- exp(coef))
  </code></pre>
  
  <p>The result doesn't have CI, only standard deviation, so my question is how can I transform SE of AFT coefficient into PH coefficient then compute the CI of HR.</p>
  
  <p>I'm kinda stuck here. Can someone help?</p>