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Poor Adherence Threatens Efavirenz More in Blacks Than Whites
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Mark Mascolini
XVI International AIDS Conference, Toronto
August 15, 2006
Adhering to efavirenz regimens took on added urgency for black patients with a new analysis of adherence and virologic failure in AIDS Clinical Trials Group (ACTG) study A5095 [1]. ACTG researchers offered strong evidence that faulty adherence heightens the risk of virologic failure more in blacks than whites taking efavirenz, at least in the US populations analyzed in this study.
ACTG A5095 chief Roy Gulick reported earlier that efavirenz failed in blacks more than in whites enrolled in this trial [2]. That earlier analysis also showed worse adherence among blacks than whites taking efavirenz. The new study details the link between wobbly adherence and virologic failure in blacks versus whites.
This placebo-controlled trial randomized treatment-naive people to add abacavir, efavirenz, or both drugs to AZT/3TC. A few years ago Gulick surprised many with the news that the triple-nucleoside regimen significantly lagged the efavirenz combinations in viral control [3]. The trial continued with the two efavirenz groups, and the four-drug regimen did no better than the three-drug regimen after 3 years of follow-up [2].
In the new study the ACTG team used four methods to calculate adherence:
- 4-Day recall: reporting not missing any doses of any active agent during the 4 days before the evaluation
- Weekend: reporting not missing any doses of any active agent during the weekend before the evaluation
- Last month: reporting not missing any doses of any active agent within the last month
- Never missed: reporting not missing any doses of any active agent during the 4 days before the evaluation AND reporting never skipping medications
Overall adherence averaged 84% for 4-day recall, 90% for last weekend, 67% for last month, and 48% for never missed. Defining virologic failure as a confirmed viral load above 200 copies/mL, the ACTG found that people with recent nonadherence had a higher risk of virologic failure than recently adherent people by all four adherence tests (P < 0.02).
As Gulick and colleagues already knew, blacks had worse adherence than whites in this trial. But they learned something new when they looked at the four adherence measures in whites and blacks: Efavirenz failed in significantly higher proportions of nonadherent blacks than nonadherent whites.
For example, 32 whites were nonadherent by the 4-day recall, and 6 (19%) endured a virologic failure. In contrast, 50 blacks reported nonadherence on 4-day recall, and 23 of them (46%) suffered virologic failure, a highly significant difference from the failure rate in white nonadherent patients (P < 0.001). Among 18 whites scoring themselves nonadherent on the weekend test, 2 (11%) had virologic failure. Among 29 blacks nonadherent on that test, 15 (52%) had virologic failure (P < 0.001).
The same disparity, at the same significance level, held true for the other two adherence tests. In addition, time to virologic failure proved faster when comparing nonadherent with adherent blacks, but not when comparing nonadherent with adherent whites, according to the last-month test (P < 0.01), the never-missed test (P = 0.04), and the last-week test (P = 0.05), but not the 4-day recall (P = 0.17).
The ACTG researchers did not speculate on why poor adherence jeopardizes the response to efavirenz so much more in blacks than in whites.
References
1. Schackman B, Ribaudo H, Krambrink A, et al. Racial differences in self-reported adherence and association with virologic failure on efavirenz-containing regimens for initial HIV therapy: results from ACTG A5095. XVI International AIDS Conference. August 13-18. Toronto. Abstract TUPE0113.
2. Gulick RM, Ribaudo HJ, Shikuma CM, et al. Three- vs four-drug antiretroviral regimens for the initial treatment of HIV-1 infection: a randomized controlled trial. JAMA 2006;296:769-781.
3. Gulick RM, Ribaudo HJ, Shikuma CM, et al. Triple-nucleoside regimens versus efavirenz-containing regimens for the initial treatment of HIV-1 infection. N Engl J Med 2004;350:1850-1861.
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