R: Ddiabetic retinopathy

diabetic {survival} | R Documentation

## Ddiabetic retinopathy

### Description

Partial results from a trial of laser coagulation for the treatment of diabetic retinopathy.

### Usage

    data("diabetic")

### Format

A data frame with 394 observations on the following 8 variables.

`id`

  subject id

`laser`

  laser type: `xenon` or `argon`

`age`

  age at diagnosis

`eye`

  a factor with levels of `left` `right`

`trt`

  treatment: 0 = no treatment, 1= laser

`risk`

  risk group of 6-12

`time`

  time to event or last follow-up

`status`

  status of 0= censored or 1 = visual loss

### Details

The 197 patients in this dataset were a 50% random sample of the patients with "high-risk" diabetic retinopathy as defined by the Diabetic Retinopathy Study (DRS). Each patient had one eye randomized to laser treatment and the other eye received no treatment. For each eye, the event of interest was the time from initiation of treatment to the time when visual acuity dropped below 5/200 two visits in a row. Thus there is a built-in lag time of approximately 6 months (visits were every 3 months). Survival times in this dataset are therefore the actual time to blindness in months, minus the minimum possible time to event (6.5 months). Censoring was caused by death, dropout, or end of the study.

### References

Huster, Brookmeyer and Self, Biometrics, 1989.

American Journal of Ophthalmology, 1976, 81:4, pp 383-396

### Examples

    # juvenile diabetes is defined as and age less than 20
    juvenile <- 1*(diabetic$age < 20)
    coxph(Surv(time, status) ~ trt + juvenile, cluster= id,
                data= diabetic)

[Package survival version 3.2-7 Index]