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Giving Efavirenz With Rifampin Does Not Hurt 3-Year HIV/TB Outcome
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4th IAS Conference on HIV Pathogenesis, Treatment, and Prevention
July 22-25, 2007
Sydney, Australia
Mark Mascolini
Combining efavirenz with rifampin in people coinfected with HIV and TB did not raise the risk of disease progression, according to results of a 3-year cohort study in India [1]. Giving these drugs together poses some risk, because rifampin lowers efavirenz levels 20% to 30%, especially in heavy people. But earlier work by these clinicians found no evidence that rifampin hurt the antiviral activity of standard-dose efavirenz through 9 months of treatment [2]. And US regulators offer no dose-adjustment advice when the drugs are given together.
To track long-term trends in HIV/TB-coinfected people treated with rifampin and efavirenz, these researchers monitored CD4 counts in two groups from their original study: 195 coinfected people who took rifampin-containing anti-TB therapy with an efavirenz-based regimen for 9 months, and 188 people infected only with HIV who took efavirenz but not rifampin.
Before treatment began, the coinfected group had a significantly lower CD4 count (median 90 versus 126, P = 0.0005). But after 9 months of anti-TB therapy, median CD4 counts no longer differed significantly between the two groups (P = 0.1395). The groups did not differ significantly in median age (36 years in both groups) weight (54 kg with TB, 56 kg without TB), or proportion of men to women.
After 9 months of rifampin plus efavirenz, median CD4 count rose to about 200 in both the coinfected group and the HIV-only group. At that point coinfected people stopped taking rifampin and other anti-TB drugs, and everyone continued an efavirenz-based regimen. CD4 counts continued to climb in both groups, approaching 250 after 18 months of observation, 300 after 27 months, and 400 after 36 months.
Throughout the 3-year observation, the groups did not differ in keeping follow-up appointments or in death rate. The investigators rated adherence as "regular" in 61.5% of the TB group and 65.4% of the non-TB group and "irregular" in the remainder. These differences lacked statistical significance.
Treatment failure, defined as a 30% or greater drop in CD4 count or clinical progression, affected 23 people with TB (11.8%) and 19 (10.1%) without TB, a nonsignificant difference (P = 0.715). While 36 people (18.5%) in the TB group were rated as treatment failures because they stopped returning for visits, 26 (13.8%) in the non-TB group were counted as failures for this reason, also a nonsignificant difference (P = 0.275). The researchers attributed these dropouts to the great distances (200 miles or more) that many patients live from the clinic.
Hepatitis was the only treatment-related problem that affected more people with TB than without TB (13.3% versus 2.1%, P = 0.0001). All cases resolved when the clinicians stopped hepatotoxic drugs. Seven people with TB and 2 without TB replaced efavirenz with nevirapine during the study. Rates of gastrointestinal problems, central nervous system side effects, rash, and peripheral neuropathy were almost identical in the two groups.
The clinicians noted that their analysis suffers from lack of virologic data, but HIV loads are not routinely measured in their clinic. Neither did they measure efavirenz concentrations during rifampin therapy. They also mentioned that the 9-month instead of typical 6-month course of anti-TB therapy is standard in their clinic.
References
1. Patel K, Patel A, Naik E, et al. TB co-infection treated at onset of therapy does not affect long-term risk of treatment failure among HIV-1 patients initiating efavirenz (EFV)-based combination antiretroviral treatment (cART). 4th IAS Conference on HIV Pathogenesis, Treatment, and Prevention. July 22-25, 2007. Sydney. Abstract MOAB103.
2. Patel A, Patel K, Patel J, et al. Safety and antiretroviral effectiveness of concomitant use of rifampicin and efavirenz for antiretroviral-naive patients in India who are coinfected with tuberculosis and HIV-1. J Acquir Immune Defic Syndr. 2004;37:1166-1169.
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