AEGiS-GMHC: New AZT Study Questions Early Use

Important note: Information in this article was accurate in 1991. The state of the art may have changed since the publication date.

New AZT Study Questions Early Use

TREATMENT ISSUES -- The GMHC Newsletter of Experimental AIDS Therapies, Vol 5, No. 2, - Feb 25, 1991
Kevin Armington

A recently completed study on the benefits of early-use AZT has been extensively, and often inaccurately, covered in the lay media. This study, conducted at several Veteran's Administration hospitals (VAs) throughout the country, evaluated 338 participants -- half started AZT when their T4 counts fell below 500, and the other half waited until their counts reached 200 before beginning treatment. The authors claim that there was no difference in overall survival for people starting AZT early vs. late. They did conclude that AZT slowed progression of HIV disease, but that this benefit was not experienced by people of color.

Many factors throw the conclusions of the VA study into question. For instance, trial participants received an enormous dose of AZT: 1500 mg/day. AZT was originally licensed at 1200 mg/day for people with AIDS, ARC or T4 counts below 200. Studies since then have demonstrated that 600 mg/day is possibly more effective. When the licensing for AZT was expanded to include people with T4 counts under 500, the dose indicated was 500 mg/day. In addition, a recent study has hinted that 300 ma/day might be just as effective as 600 mg/day. Test tube studies have shown that people on higher doses develop resistance to AZT faster than those on lower doses perhaps a factor effecting the outcome of the VA study.

It is interesting to note that six cases of dementia occurred in this trial, all in the delayed treatment group. This finding would seem to support early use of AZT, from a neurological standpoint.

Many of the news reports in the lay press on this study reported that people of color did not gain benefit from AZT in this study. What these reports failed to note is that most of the participants who are people of color had lower red and white blood cell counts on average at the beginning of the study. Considering the toxicity of the excessive dose used, it is not surprising that people with lower blood cell counts progressed more rapidly. This study was not designed to measure whether different racial groups derive more or less benefit from AZT, so this phenomenon cannot be considered an accurate analysis of any potential difference. Three other major AZT studies have shown no difference in racial groups receiving AZT. But it is remarkable that reliable studies have not been done yet to specifically answer this question.

Finally, this study is much smaller than two other studies that have shown a clear difference in progression to AIDS for people receiving no treatment vs. AZT. Trial 016 conducted by the AIDS Clinical Trials Group evaluated 711 patients and trial 019 evaluated 1338 patients. These placebo-controlled studies stand in sharp contrast to the VA study, in which everyone received AZT, but at different stages. The larger trials show that participants receiving A ZT have delayed disease progression. Many of the original trial participants are still being followed, but no data showing a difference in survival have been reported yet. If these data are available, they must be made public as soon as possible.

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