The CGD data set presented by Fleming and Harrington (1991) and Therneau and Lumley (2015) consists of a placebo-controlled randomized trial of gamma interferon (rIFN-g) in the treatment of chronic granulomatous disease (CGD). 128 patients from 13 centers were tracked for around 1 year. The number (i.e., cluster size) of patients per center ranged from 4 to 26. The survival times are the recurrent infection times of each patient from the different centers. Censoring occurred at the last observation for all patients, except one, who experienced a serious infection on the data he left the study; in the CGD study about 63 per cent of the data were censored. The recurrent infection times for a given patient are likely to be correlated. However, each patient belongs to one of the 13 centers; hence, the correlation may also be attributed to a center effect.
data("cgd")A data frame with 203 observations on the following 16 variables.
idsubjects identifier for 128 patients
centerenrolling center for 13 centers
randomdate of randomization
treata factor with levels placebo and rIFN-g (gamma interferon)
sexa factor with levels male and female
ageage in years at study entry
heightheight in cm at study entry
weightweight in kg at study entry
inherita factor for pattern of inheritance with levels X-linked and autosomal
steroidsuse of steroids at study entry with 1 (=yes) and 0(=no)
propylacuse of prophylactic antibiotics at study entry
hos.cata factor for centers into 4 goups with levels US:NIH, US:other, Europe:Amsterdam and Europe:other
tstartstart of each time interval
enumobservation number within subject
tstopend of each time interval
statusstatus with 1 for infection and 0 for censoring
Fleming, T.R. and Harrington, D.P. (1991). Counting Processes and Survival Analysis. John Wiley and Sons, New York.
Therneau, T. and Lumley, T. (2015). survival: Survival Analysis. R package version 2.38-3.