Expert: Effectiveness of AIDSVAX among blacks, Asians may be overstated
BY Advocate.com Editors
February 28 2003 1:00 AM ET
VaxGen officials may have overstated the effectiveness of their AIDS vaccine among blacks and Asians by not making the proper statistical adjustments to their Phase III clinical trial data, The New York Times reports. Steven Self, a professor of biostatistics at the University of Washington who was hired as a consultant by VaxGen, said Wednesday that the company should have lowered the level of confidence with which it said the vaccine appeared to protect blacks, Asians, and other non-Hispanic
minorities from infection by HIV.
While the study data showed that AIDSVAX failed to significantly reduce HIV infection rates overall, only four of the 203 black study subjects who received the vaccine tested positive for HIV antibodies during the course of the three-year study, compared with nine of 111 blacks who received a placebo. Of 54 Asians who received the vaccine, only two tested positive, compared with two of 20 Asians who received placebos. Based on these findings, VaxGen officials said they planned to continue developing AIDSVAX for possible use in these minority communities.
VaxGen reported that its findings for the minority subgroups had a confidence interval of 30.2% to 84.2%, meaning that there was a 95% probability that the actual efficacy of the vaccine fell somewhere between those two points, Self said. But he said that by his calculation the low end of that interval should have been nearly zero, meaning that while the actual efficacy could be very high, it also could be almost entirely ineffective. Self said the company should have lowered its confidence to account for the fact that it analyzed multiple subgroups of patients. "It's probably an honest error," Self said.
VaxGen president Donald Francis said company officials are still discussing how to properly evaluate the statistical data but added that even if the efficacy claims have to be lowered, the trial results still show that the vaccine did have better results--if only slightly better--among blacks and Asians.