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Chart Review Confirms Worse Virologic Response to PIs Than Efavirenz in Women
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52nd ICAAC, September 9-12, 2012, San Francisco
Mark Mascolini
Retrospective analysis of women and men starting their first antiretrovirals in Chicago confirmed an earlier randomized trial that found a higher virologic failure rate in women randomized to a protease inhibitor (PI, atazanavir/ritonavir) versus efavirenz [1]. The chart review also found a trend toward lower virologic suppression rates in women than men taking a first-line PI regimen.
ACTG A5202 randomized antiretroviral-naive adults to efavirenz or atazanavir/ritonavir plus tenofovir/emtricitabine or abacavir/lamivudine [2]. The trial was the first to show a higher virologic failure rate in women randomized to the PIs than efavirenz [3]. Safety, tolerability, and adherence did not appear to explain this difference. Women randomized to atazanavir/ritonavir in ACTG A5202 also had a higher failure rate than men randomized to the PIs. The findings have implications throughout the world because HIV-positive women of child-bearing age often start a PI regimen to avoid the teratogenic effects of efavirenz. And in many places newer nonnucleosides and integrase inhibitors are not readily available.
Researchers at Chicago's Ruth M. Rothstein Core Center and Cook County Hospital conducted this chart review to compare virologic response rates in women and men starting their first regimen with efavirenz or ritonavir-boosted atazanavir, darunavir, fosamprenavir, or lopinavir. Study participants were all older than 14 and antiretroviral naive when they began treatment. All had pretreatment genotyping, and none had detectable nonnucleoside mutations. The researchers defined virologic success as a viral load below 200 copies 6 months after treatment began, and everyone had at least 6 months of follow-up and two follow-up visits.
The analysis included 90 people who started a PI (64 men and 26 women) and 268 who started efavirenz (219 men and 49 women). While 35% of women started a PI, 23% of men started a PI regimen. PI takers were younger than efavirenz takers (29 versus 34 years, P = 0.01), but racial distributions were similar. Most participants in the PI group (71%) and the efavirenz group (68%) were African American, while similar proportions of the remaining people were white or Hispanic.
Similar proportions of women and men discontinued treatment with a PI (46% and 38%) or efavirenz (37% and 33%). After 6 months of follow-up, a nonsignificantly higher proportion of women taking efavirenz than a PI had an undetectable viral load (93% versus 79%, P = 0.11). The 79% PI response rate in women compared with a 90% response rate in men.
After 12 months of follow-up a significantly higher proportion of women taking efavirenz than a PI had an undetectable viral load (96% versus 72%, P = 0.03). At 12 months virologic response rates were similar in men taking efavirenz or a PI (92% and 93%). The 12-month PI response difference between women and men (72% versus 93%) approached statistical significance (P = 0.09). Race, baseline viral load, or baseline CD4 count did not affect response to PIs versus efavirenz.
The CORE Center team concluded that their results confirm the gender-based findings of ACTG A5202. They suggested that nonnucleoside-based regimens "may provide higher success rates compared with PIs in treatment-naive women." However, the numbers in this nonrandomized comparison were small: At 12 months 18 women and 40 men were taking a PI and 26 women and 145 men were taking efavirenz.
References
1. Patel J, Livak B, Cole J, et al. Efficacy and use of PI vs EFV in treatment naive HIV+ men and women. 52nd Interscience Conference on Antimicrobials and Chemotherapy (ICAAC). September 9-12, 2012. San Francisco. Abstract H-883.
2. Sax PE, Tierney C, Collier AC, et al. Abacavir-lamivudine versus tenofovir-emtricitabine for initial HIV-1 therapy. N Engl J Med. 2009;361:2230-2240.
3. Smith K, Tierney C, Daar E, et al. Association of race/ethnicity and sex on outcomes in ACTG Study A5202. 18th Conference on Retroviruses and Opportunistic Infections. February 27-March 2, 2011. Boston. Abstract 563. http://www.retroconference.org/2011/Abstracts/41176.htm.
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