DSMB case study: decision making when a similar clinical trial is stopped early.

Two similarly designed, placebo-controlled clinical trials are fully accrued and following patients for safety and outcome data. One trial is stopped at a planned interim analysis by its data safety and monitoring board (DSMB) due to a statistically significant treatment benefit. The statisticians and DSMB of the other trial are informed of these results. What are the responsibilities of the statistical center? How should the DSMB deal with the situation if the data do not support the stopped trial? What should the patients be told concerning the results of the two trials when one trial continues and the other is stopped? This DSMB case study reports on such a situation for two randomized clinical trials of oral ganciclovir for the prevention of cytomegalovirus disease in HIV/AIDS patients.