Dendreon Corp fka DNDNQ

[rancherho]

COMMENTS AND CONTROVERSIES
Randomized Trials in Oncology Stopped Early for Benefit
Journal of Clinical Oncology, Vol 26, No 1 (January 1), 2008: pp. 18-19
http://jco.ascopubs.org/cgi/content/full/26/1/18
"The relative risk (RR), either reported or calculated, and total number of events were available for all those RCTs reporting dichotomous end points (n = 27). The median RRs and total number of events were 0.54 (interquartile range, 0.3 to 0.7) and 61 (interquartile range, 23 to 144), respectively. Nine of the 12 RCTs that reported a RR the median RR reported more than the median number of events. Conversely, the majority of RCTs (73%) that found an RR less than the median also reported fewer than the median number of events, suggesting that RCTs stopped early after only a few events accrued tend to report large treatment affects. Indeed, the odds of reporting a large treatment effect (ie, a RR less than the median) were 12.2 times (95% CI, 2.0 to 75.1) greater when the studies accrued fewer than the median number of events than when they stopped later, after more events had occurred. The correlation between the number of events and the apparent treatment effect, expressed as an RR, was highly significant (r = 0.75; P < .0001). Therefore, the risk of significantly overestimating the treatment effect diminishes when the number of events accrued is large. While preliminary explorations suggest that subsequent trials confirmed the statistical significance of 64% of trials stopped early for benefit in oncology, we are concerned with the overestimation of the true treatment effect and how this could affect risk-benefit tradeoffs necessary for sound clinical decision making.3 Given the strong correlation between the apparent treatment effect and the number of events, it would seem prudent to perform interim analyses only after a sufficient number of events have occurred so as to reduce the likelihood of overestimating the true treatment effect."