Nonparametric Comparison of Two Survival Time Distributions in the Presence of Dependent Censoring

• Activity Number: 152
• Type: Contributed
• Date/Time: Monday, August 12, 2002 : 2:00 PM to 3:50 PM
• Sponsor: Biometrics Section*
• Author(s): Gregory DiRienzo*+
• Affiliation(s): Harvard School of Public Health
• Keywords: clinical trial ; survival analysis ; sensitivity analysis ; log-rank test

Abstract

When the distribution of censoring time is independent of randomized treatment group, the logrank test of the null hypothesis, that treatment-specific survival time distributions are equal, is asymptotically valid. We introduce a test of the null for use when the distribution of censoring depends on treatment group and, further, on survival. This test does not make any assumptions regarding independence of censoring and survival distributions. Asymptotic validity of this test only requires a consistent estimate of the conditional probability that the survival event is observed given both treatment group and that the survival event occurred before the time of analysis. However, by not making unverifiable assumptions about the data generating process for each treatment group, all that can be identified from the observed data is the interval within which the corresponding sample mean estimate of this probability must lie. Over this rectangle in the unit square, the proposed test can be calculated, and a rejection region identified. A decision on the null that considers uncertainty because of censoring that may depend on treatment group and, further, on survival can then be made.