May 31, 2007 — Standard 6-month therapy for tuberculosis (TB) might be insufficient to prevent relapse in patients with HIV, according to the results of a study reported in the June 1 issue of the American Journal of Respiratory and Critical Care Medicine.
"The preferred regimen for the treatment of drug-susceptible tuberculosis in HIV-uninfected individuals is a 6-month, rifamycin-based regimen that includes pyrazinamide during the initial 2-month phase," write Payam Nahid, from the San Francisco General Hospital, University of California in San Francisco, and colleagues. "There continues to be controversy about the optimal duration of treatment for tuberculosis in HIV-infected patients."
The objective of this study was to evaluate treatment outcomes in a low-incidence setting, where HIV-infected patients were managed at a TB control program without significant resource limitations and were stratified by duration of rifamycin-based TB therapy.
The investigators retrospectively reviewed data on all 700 patients with TB reported to the San Francisco Tuberculosis Control Program from 1990 to 2001 with follow-up for up to 12 months after treatment completion.
Of the 700 patients, 264 (38%) were HIV-infected, 315 (45%) were not infected, and 121 (17%) were not tested. For the HIV-infected patients, the mean duration of treatment was extended to 10.2 months, compared with 8.4 months for uninfected patients and those of unknown HIV status (P < .001). Rifamycin-based therapy for 6 months was given to 17% of the HIV-infected patients and to 37% of the other patients.
The relapse rate was 9.3 per 100 person-years in HIV-infected patients, compared with 1.0 in HIV-uninfected/unknown patients (P < .001). HIV-infected patients who received a standard 6-month rifamycin-based regimen were more likely to relapse than were those who were treated for longer periods (adjusted hazard ratio, 4.33; P = .02).
Compared with HIV-infected individuals who were treated daily, those who received intermittent therapy were also more likely to relapse (adjusted hazard ratio, 4.12; P = .04). Use of highly active antiretroviral therapy was associated with faster conversion of smears and cultures and with increased survival.
"HIV-infected patients who received a 6-month rifamycin-based course of tuberculosis treatment or who received intermittent therapy had a higher relapse rate than HIV-infected subjects who received longer therapy or daily therapy, respectively," the authors write. "Standard 6-month therapy may be insufficient to prevent relapse in patients with HIV."
Study limitations include potential biases, such as the effect of physician preference for prolonging treatment in HIV-infected patients; difficulty in determining cause of death; retrospective design; database initiated in the early 1990s when the immune reconstitution syndrome in HIV-infected patients was first described, allowing limited data acquisition on this syndrome; and differential attrition in the 2 groups.
"Despite the varying recurrence rates noted in the literature, the generally recommended treatment for HIV-infected patients with tuberculosis is 6 months of a rifamycin-based regimen. Based on our findings, we recommend...further research...to identify the most efficacious duration of therapy and the optimum timing for HAART [highly active antiretroviral therapy] in the treatment of HIV-related tuberculosis."
The National Institutes of Health (NIH) through the NIH Roadmap for Medical Research, National Institute of Allergy and Infectious Diseases, and the American Lung Association supported this study. None of the authors report any relevant financial relationships.
In an accompanying editorial, David C. Perlman, MD, from Beth Israel Medical Center in New York City, and colleagues noted that regimens should not be evaluated solely on the basis of failure-relapse rates, but perhaps should be evaluated on rates of acquired resistance.
"Erratic access to secondline anti-TB drugs in areas with high HIV prevalence has proven a fertile ground for the emergence of XDR-TB [extensively drug-resistant tuberculosis]," the editorialists write. "However, in the treatment of HIV-related TB, access to essential drugs alone is far from sufficient. To avert a looming disaster, there is an urgent need to strengthen both the HIV and TB control programs in areas with high rates of HIV-related TB."
None of the authors report any relevant financial relationships.
Am J Resp Crit Care Med. 2007;175:1102-1103, 1199-1206.
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