IAS: TB and HIV Therapy Can Co-Exist

SYDNEY, July 23 -- Tuberculosis and HIV therapy can take place at the same time without the risk of long-term HIV treatment failure, researchers said here.

In a prospective longitudinal cohort study of HIV patients with and without TB, the long-term risk of HIV treatment failure was the same regardless of TB therapy, according to Ketan Patel, M.D., of the Infectious Diseases Clinic in Ahmedabad, India.

The finding appears to put to rest fears that TB treatment with rifampin (Rifadin) increases the risk of simultaneous treatment with efavirenz (Sustiva); Dr. Patel told an oral abstract session of the International AIDS Society meeting. Rifampin is known to reduce plasma levels of many HIV drugs, including efavirenz.

Dr. Patel and colleagues showed in 2004 that co-administration of rifampin and an HIV regimen based on efavirenz at 600 mg/day had no effect on the anti-viral efficacy of the HIV drugs.

But it remained possible, he said, that the durability of the response might be affected by the interaction of the drugs. To find out, he and colleagues followed 383 patients for a minimum of 12 months and up to three years.

Of those, 195 had both TB and HIV and were treated for nine months with a rifampin-based TB regimen, while at the same time getting efavirenz and other HIV medications.

At the beginning of therapy, the TB group had an average CD4 cell count that was significantly lower (P=0.0005) than those without TB -- 90 versus 126 cells per microliter of plasma.

But by the end of the TB treatment, there was no significant difference in CD4 cell count between the groups, Dr. Patel said. Indeed, he added, CD4 cell improvements were comparable between the groups et every point up to three years of follow-up.

The key indicator was immunological treatment failure, he said, which was defined as a drop of more than 30% in the CD4 cell count from the start of therapy.

The study found that 23 of the TB group and 19 of the non-TB patients had an immunological failure -- or 11.8% versus 10.1% -- which was not significantly different.

Even when patients lost to follow-up were counted as failures, he said, the treatment failure rates did not differ significantly between the arms.

Adverse events were also similar between the groups, Dr. Patel said, with the exception that there was more hepatitis in the TB group -- 26 cases versus four (P=0.0001).

The take-home message of the study is that "treatment of HIV and TB co-infection is possible to do with concomitant therapy with both good short- and long-term outcomes," commented Gerald Friedland, M.D., of Yale, who chaired the session.

Dr. Friedland said more studies are needed to pinpoint "the perfect time" to start treating both infections, but this research suggests that co-therapy fears are exaggerated.

It appears that "concerns about the dangers of anti-retrovirals are being outweighed by the mortality that might be prevented," he said, "but we need more studies to show that."