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Cotrimoxazole failed to reduce TB incidence in HIV patients
The incidence of Mycobacterium tuberculosis was unchanged in patients with HIV who received daily cotrimoxazole prophylaxis, and the treatment does not appear to confound the diagnosis of tuberculosis, according to new study data published online.
“In vitro data have suggested that cotrimoxazole has activity against Mycobacterium tuberculosis; yet studies of cotrimoxazole prophylaxis in Africa have not demonstrated an effect on TB incidence,” researchers wrote. “In addition to the potential of reducing TB incidence or mortality, of theoretical concern is that anti-mycobacterial activity of cotrimoxazole could make detection of TB more difficult by reducing the proportion of TB patients with smear positive disease, or prolonging time to mycobacterial culture positivity.”
Christopher J. Hoffmann, MD, MPH, of Johns Hopkins University School of Medicine and Center for TB Research, and colleagues assessed the incidence of TB and culture characteristics of 2,590 adult patients seeking HIV care in Soweto, South Africa. The researchers compared both the total and laboratory-confirmed TB incidence among patients receiving and not receiving once-daily cotrimoxazole prophylaxis. TB culture results of patients receiving and not receiving the treatment also were compared. Patients were followed from April 2003 to December 2009.
Christopher J. Hoffmann
The researchers found that the risk for TB increased among patients assigned cotrimoxazole (HR=1.7; 95% CI, 1.2-2.2). However, Hoffmann and colleagues said this finding may be the result of “residual confounding,” since the association between TB disease and cotrimoxazole status ceased after analyses were restricted to laboratory-confirmed TB cases (HR=0.97; 95% CI, 0.39-2.4).
The proportion of positive cultures and the time to mycobacterial culture positivity were similar among patients receiving and not receiving cotrimoxazole.
Additional analyses indicated that cotrimoxazole prophylaxis was associated with a reduced mortality risk (HR=0.48; 95% CI, 0.21-1.1).
Despite the questionable association between cotrimoxazole and increased TB risk, Hoffmann and colleagues said the treatment has an established benefit for patients with HIV.
“Cotrimoxazole is an essential component for reducing HIV-associated mortality but does not have an effect on TB disease,” Hoffmann told Infectious Disease News. – John Schoen
Christopher J. Hoffmann, MD, MPH, can be reached at choffmann@jhmi.ed.
Disclosure: The researchers report no relevant financial disclosures.