797 
Experience Using AZT and d4T in TAHOD Patients: Treatment Duration and AZT-related Anemia
S Huffam1, P Srasuebkul2, J Zhou2, Alexandra Calmy*3, V Saphonn1, J Kaldor2, R Ditangco4, and The TREAT Asia HIV Observational Database (TAHOD)
1Natl Ctr for HIV/AIDS, Dermatology and STDs, Ministry of Hlth, Cambodia; 2Natl Ctr for HIV Epidemiology and Clin Res, Univ of New South Wales, Australia; 3St Vincent's Hosp, Sydney, Australia; and 4Res Inst for Tropical Med, Philippines
Background:
In resource-poor
settings, the choice of zidovudine (ART) is strongly driven by affordability
and availability. However, concern regarding AZT-related anemia also limits AZT
use in initial ART regimens. If AZT is less likely to cause anemia
following immune reconstitution, subsequent switch from stavudine (d4T) to AZT
to avoid long-term toxicities closely associated with d4T may be a viable
treatment strategy.
We investigated the duration of AZT and d4T, and factors related to anemia in
patients receiving AZT, using data from TAHOD, a multicenter prospective
observational HIV cohort.
Methods:
Cox proportional hazards models were used to
determine factors related to stopping AZT and d4T in an initial 3-drug ART regimens.
Logistic regression was used to determine factors related to anemia within the
first 6 months of commencing AZT in initial or subsequent regimens.
Results:
Of the 2979 patients in TAHOD, 1655 who had commenced
d4T or AZT were included in analysis for treatment change, and 437 who had
commenced AZT for development of anemia. The
overall stop rate was 17 (95%CI 16 to 19)/100 person-years, including 17 (95%CI
16 to 19)/100 person-years, and 18 (95%CI 16 to 21)/100 person-years for d4T
and AZT, respectively. Factors related to stopping AZT or d4T were: age/10
years (HR 1.10, 95%CI 1.01 to 1.20), female gender (HR 1.24, 95%CI 1.03 to 1.50),
and current tuberculosis (HR 1.32, 95%CI 1.05 to 1.67). Stopping d4T was less
common than stopping AZT within the first 9 months of ART (HR 0.51, 95%CI 0.39 to
0.67), while stopping d4T was more common than stopping AZT after 9 months of
ART (HR 2.27, 95%CI 1.64 to 3.13). Anemia (Hb ≤10 g/dL) occurred in the
first 6 months in 61 of 437(14%) patients commenced on AZT, including severe anemia
(Hb <7.5 g/dL) in 11 of 437(2.5%). Factors
related to development of anemia on AZT were: age/10 years (OR 1.56, 95%CI 1.10 to 2.06),
female gender (OR 3.46, 95%CI 1.68 to 7.13), injecting drug user and unknown
exposure category (OR 2.70, 95%CI 1.42 to 5.17), baseline anemia (OR 9.81,
95%CI 5.31 to 18.09), current AIDS-defining illness (OR 3.99, 95%CI 2.45 to 6.52),
current tuberculosis (OR 5.32, 95%CI 1.90 to 14.88), and ART-experienced (OR
0.24 95%CI 0.09 to 0.58).
Conclusions:
Baseline
anemia strongly predicts development of anemia on AZT, which supports
baseline testing and avoidance of AZT if the patient is anemic. The only
protective factor for the development of AZT-related anemia was being ART
experienced. While further study is needed, this lends support to the safety of
d4T to AZT switch in populations with advanced HIV.
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