In a retrospective study of 700 patients with culture-positive tuberculosis (TB), relapse rates were found to be significantly higher in HIV-infected patients compared to HIV-uninfected patients following a rifamycin-based regimen. Furthermore, TB relapse rates were higher in HIV-infected patients who received intermittent or standard 6-month therapy when compared to those receiving daily or longer treatment.
The results appear in the first issue for June 2007 of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.
Payam Nahid, M.D., M.P.H., of the University of California, San Francisco General Hospital, and eight associates reviewed TB cases reported to the San Francisco Tuberculosis Control Program from January 1, 1990, through December 31, 2001.
As a rationale for their study, the researchers state that the optimal duration of TB therapy in HIV-infected subjects is unknown and may differ from HIV-uninfected individuals.
According to the authors, the current preferred regimen for treating drug-susceptible TB in HIV-uninfected patients is a 6-month, rifamycine-based regimen that includes pyrazinamide during the first two months. Current guidelines for the treatment of TB do not distinguish between those infected with the virus that causes AIDS and those who are uninfected in terms of the optimum length of treatment when using rifamycine.
"Standard 6-month therapy may be insufficient to prevent relapse in patients with HIV," said Dr. Nahid.
The TB relapse rate for HIV-infected patients was found to be 6.6 percent versus 0.8 percent in uninfected/unknown patients. This finding was in contrast to other studies that did not find any significant difference between HIV-infected and HIV-uninfected/unknown patients. However, this finding was corroborated by a similar study that also used molecular genotyping as a relapse indicator.