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doi: 10.1097/QAD.0b013e32834d0c20
Clinical Science

Initial viral decay to assess the relative antiretroviral potency of protease inhibitor-sparing, nonnucleoside reverse transcriptase inhibitor-sparing, and nucleoside reverse transcriptase inhibitor-sparing regimens for first-line therapy of HIV infection

Haubrich, Richard H.a; Riddler, Sharon A.b; Ribaudo, Heatherc; DiRenzo, Gregoryc,d; Klingman, Karin L.e; Garren, Kevin W.f; Butcher, David L.g; Rooney, James F.h; Havlir, Diane V.i; Mellors, John W.b; for the AIDS Clinical Trials Group (ACTG) A5160 and A5142 Study Teams

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Objectives: To evaluate the effects of sex and initial antiretroviral regimen on decay of HIV-RNA and virologic outcome.

Methods: We conducted a viral dynamics substudy of A5142, a trial comparing lopinavir (LPV)/ritonavir with efavirenz (LPV/EFV) versus LPV and two nucleoside reverse transcriptase inhibitor (NRTI) (LPV) versus EFV and two NRTI (EFV) in antiretroviral (ARV)-naive individuals. HIV-RNA was measured at days 2, 10, and 14 in the substudy and at weeks 1, 4, and 8 in A5142 participants. Two-phase viral decay was estimated in the substudy with biexponential mixed-effects modeling and compared using Wilcoxon tests. Week 1 HIV-RNA change was assessed as a predictor of virologic failure (HIV-RNA above 50 or 200 copies/ml) at weeks 24–96 using logistic regression.

Results: Sixty-eight individuals were enrolled in the substudy (median HIV-RNA 4.9 log10 copies/ml). Median rates of phase 1 viral decay by treatment were 0.61(EFV/LPV), 0.53(LPV), and 0.63(EFV) per day. Phase 1 decay was significantly faster for EFV than LPV (P = 0.023); other comparisons were not significant (P > 0.11). Viral decay did not differ by sex (P = 0.10). Week 1 HIV-RNA change, calculated in 571 participants of A5142, was greater for the EFV (median −1.47 log10 copies/ml) than either the LPV/EFV or LPV groups (−1.21 and −1.16 log10 copies/ml, respectively; P < 0.001). Week 1 HIV-RNA change was associated with virologic failure above 50 copies/ ml at weeks 24 and 48 (P< 0.018), but not above 200 copies/ml at these time points or for any value at week 96.

Conclusion: Phase 1 decay was faster for EFV than LPV or LPV/EFV. Week 1 HIV-RNA change predicted virologic outcome up to week 48, but not at week 96.

© 2011 Lippincott Williams & Wilkins, Inc.


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