The Relationship between the Human Immunodeficiency Virus and the Acquired Immunodeficiency Syndrome (Draft)

DRAFT
mortality (reviewed in McLeod and Hammer, 1992; Sande et al., 1993). The lack of excess
AIDS cases and death in the AZT arms of these trials effectively rebuts the argument that AZT
causes AIDS.
During a 4.5 year follow-up period of ACTG 019, no differences were seen in overall
survival between AZT and placebo groups among patients entering the study with fewer than
500 CD4+ T cells/mm3 (Volberding, et al., 1994). In that study, AZT was superior to placebo
in delaying progression to AIDS or advanced ARC for approximately one year, and a more
prolonged benefit was seen among a subset of patients. In a recent European study of 912
asymptomatic patients with CD4+ T cell counts less than 500 mm3, no differences in survival
or progression to advanced disease were seen between AZT placebo groups after three years
(Concorde, 1993). However, the rate of progression to AIDS or severe ARC was slower in the
AZT group during the first year of therapy, a finding consistent with ACTG 019. Similar results
were noted in another European-Australian trial (Lange, 1993).
Another European-Australian study of 993 patients with CD4+ T cell counts greater
than 400/mm3 showed no differences in survival during a median study period of 94 weeks,
although AZT did delay progression to certain clinical and immunological endpoints (Cooper et
al., 1993).
Uncontrolled studies have found increased survival and reduced frequency of
opportunistic infections in patients with AIDS who were treated with AZT (Moore et al.,
1991a,b; Creagh-Kirk et al., 1988; Ragni et al., 1992; Schinaia et al., 1992; Koblin et al., 1992;
Graham et al., 1992; Vella et al., 1992; Saah et al., 1994). In addition, cohort studies show
that life expectancy of individuals with AIDS has increased since the use of AZT became
common in 1986-87 (Jacobson, et al. 1993; Harris et al., 1990; Osmond et al., 1993.) In one
cohort of homosexual men, median survival time after AIDS improved from 11.6 months in
1984-85 to 20.3 months in 1990-1991 (Jacobson et al., 1993). Another cohort found that the
time from seroconversion to death, a period not influenced by variations in diagnosing AIDS,

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