Taking anti-tuberculosis treatment at the same time as antiretroviral therapy does not reduce the virological success rate of anti-HIV treatment, a retrospective study published in the May 15th edition of The Journal of Infectious Diseases has found. The investigators, from London, also found that patients who took anti-tuberculosis and anti-HIV therapy at the same time had a similar rate of tuberculosis (TB) recurrence to that of HIV-negative patients treated for tuberculosis.
Tuberculosis is the major cause of illness and death in HIV-positive individuals around the world and one of the two most common AIDS-defining illnesses in the United Kingdom. Practical problems combining treatment for tuberculosis and HIV include an inflammatory response, overlapping side-effects, a high pill burden, and poor drug absorption. These factors could mean that anti-HIV therapy is less likely to achieve an undetectable viral load in patients taking concurrent tuberculosis and HIV therapy.
Doctors from the North Middlesex Hospital, the Royal Free Hospital, London, and University College Hospital in London hypothesized that the specialist care provided by a team skilled in both the treatment of HIV and tuberculosis would improve the effectiveness of both anti-HIV therapy and tuberculosis treatment in their patients. They therefore designed a retrospective study involving patients who received concurrent anti-tuberculosis and antiretroviral therapy at their centres between 1997 and 2003. They compared the virological and immunological outcome of these patients to match HIV-positive patients who did not have tuberculosis and who were treated with anti-HIV drugs. To determine if the concurrent use of antiretroviral treatment compromised the potency of tuberculosis therapy, treatment outcome and relapse rates of the HIV-positive tuberculosis patients were also compared with individuals who only had tuberculosis.
A total of 156 HIV-positive/tuberculosis patients were included in the investigators' analysis. Their median age was 35, 52% were men and 77% were of African origin. The median CD4 cell count at the time of tuberculosis diagnosis indicated advanced immune suppression and was 77 cells/mm3, and median viral load was 125,000 copies/ml.
A total of 29 patients were already taking anti-HIV therapy when their tuberculosis was diagnosed, and 15 of these patients already had a viral load below 50 copies/ml prior to treatment for tuberculosis being initiated. All 15 of these individuals still had a viral load below 50 copies/ml on the completion of tuberculosis therapy along with an additional eleven individuals who were already taking antiretrovirals.
Of the remaining 82 patients, anti-HIV treatment was commenced a median of two months after tuberculosis therapy was initiated. Of these 82 patients, 68 (83%) had a viral load below 50 copies/ml after six months of HIV treatment. CD4 cell counts increased in 71 patients who started HIV treatment after tuberculosis therapy (median increase at six months, 108 cells/mm3).
No difference in virological response was seen between the HIV/tuberculosis patients and 111 HIV-positive controls without tuberculosis who received HIV therapy. A total of 13% of HIV/tuberculosis patients failed to achieve a viral load below 400 copies/ml after six months of antiretroviral therapy, as did 13% of patients who only received HIV therapy. CD4 cell count increased by a median of 97 cells/mm3 in HIV/tuberculosis-treated patients after six months compared to 89 cells/mm3 in patients who were only treated for HIV.
The outcome of tuberculosis treatment in the HIV-positive patients was then compared to that of a population of 156 HIV-negative patients who were treated for tuberculosis. Similar proportions of HIV-positive (6%) and HIV-negative (4%) patients took less than their planned course of tuberculosis therapy. Tuberculosis recurred in 3% of HIV-positive patients compared to 1% of HIV-negative individuals, a non-significant difference.
“These data suggest that persons coinfected with HIV and M. tuberculosis may be treated, with good outcomes for both conditions”, write the investigators.
Breen RAM et al. Virological response to highly active antiretroviral therapy is unaffected by antituberculosis therapy. J Infect Dis 193: 1437 – 1440, 2006.