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Small But Significant CD4 Gains
When Switching Antiretrovirals With Sub-50 Load
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Tenth International Congress on Drug Therapy in HIV Infection, November 7-11, 2010, Glasgow
Mark Mascolini
People in the EuroSIDA cohort who switched antiretrovirals with an undetectable viral load gained significantly more CD4 cells per year than people who stayed with their suppressive regimen [1]. The absolute gain after switching measured only about 5 or 6 extra CD4s per year. Amanda Mocroft and EuroSIDA colleagues suggested their findings "are potentially of most relevance to patients with low CD4 counts in whom cART [combination antiretroviral therapy] had not induced optimal immunologic recovery." About 1 in 10 cohort members switched antiretrovirals every year for reasons other than virologic rebound.
The analysis involved 7071 people with a confirmed viral load below 50 copies who switched one or more antiretrovirals on the same day for any reason (except virologic rebound). Everyone had started two nucleosides (or tenofovir) plus an unboosted protease inhibitor (PI), a boosted PI, or a nonnucleoside (NNRTI). At baseline, defined as the time when viral load first fell below 50 copies, median CD4 count was 408 in switchers and 419 in nonswitchers (nonsignificant at P = 0.65), with respective lowest-ever CD4 counts of 159 and 162 (P = 0.03). Median peak viral load measured 4.7 log in switchers and 4.8 in nonswitchers (P = 0.0005). Baseline month was significantly earlier in switchers (July 2003) than in nonswitchers (September 2003) (P < 0.0001). Median years since starting antiretrovirals did not differ significantly between switchers (2.1) and nonswitchers (2.4).
In the 12 months after first undetectable viral load, the investigators estimated that 9.8% of patients switched at least one antiretroviral (95% confidence interval [CI] 9.0 to 10.6). During the entire study period (which the researchers did not define), 1110 people (15.7%) changed 1420 antiretrovirals for a switching incidence of 11.2 per 100 person-years (95% confidence interval [CI] 10.5 to 11.8). Among switchers, 254 people (23% of 1110) started a new antiretroviral class, including 26 starting a PI and 228 starting an NNRTI.
Toxicity accounted for 37% of switches, while "patient/physician choice" explained 31% of switches. The investigators proposed that "patient/physician choice" is probably "strongly correlated with toxicities." Reasons for switching from an unboosted PI, a boosted PI, or an NNRTI did not differ significantly.
People who switched antiretrovirals gained an estimated 5.9 CD4 cells per year more than people who did not switch (95% CI 2.9 to 8.9). Cohort members who switched more than one antiretroviral added an estimated 6.6 CD4s per year more than nonswitchers (95% CI 0.5 to 12.6). CD4 gains after the switch did not differ in people starting a first PI versus a first NNRTI. People recycling already-used nucleosides did not gain significantly fewer CD4s than people starting only new nucleosides.
This poster is online at the Copenhagen HIV Program site at http://www.cphiv.dk/portals/0/files/HIV10_poster_AM1.pdf.
Reference
1. Mocroft A. Changing antiretrovirals whilst viral load <50 copies/mL and relationship with CD4 count changes. Tenth International Congress on Drug Therapy in HIV Infection. November 7-11, 2010. Glasgow. Abstract P024.
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