Treatment with HAART has the potential to reduce the incidence of tuberculosis (TB) by 80% in people infected with HIV-1, according to a South African study published in the 15 June 2002 edition of The Lancet.
The issue is particularly important as TB is the leading cause of illness and death amongst people with HIV in sub-Saharan Africa. Unlike other HIV related infections, TB can occur when a person still has a relatively intact immune system and can be transmitted to people who are HIV negative. The World Health Organisation recently developed a strategic framework for the integration of HIV and TB control programmes across the globe.
Researchers at the New Somerset Hospital HIV Clinic, University of Capetown, South Africa, compared the risk of developing TB in an observational cohort study of 264 people who received HAART as part of phase III clinical trials at the clinic between 1995 and 2001, with the risk in a control population of 770 non-HAART patients seen at the clinic between 1992 and 2000.
The two groups were compared for CD4 count, WHO stage of clinical HIV disease (stages 1 and 2 minor disease, 3 and 4 major HIV disease) and social and economic status.
At baseline, the average age of the HAART group was 34.5 years compared to 32.9 years for the non-HAART. Average CD4 count was lower for those treated with HAART at 254 cells/mm3 (range 140-364 cells/mm3) against 303 cells/mm3 (range 159-468). Overall, the HAART group had experienced greater HIV disease progression with 46% (122) defined as showing WHO stage 3 and 4 disease stage against 29% (227) in the non-HAART group. There were many fewer women amongst the group given HAART because of clinical trial exclusion criteria preventing pregnant or nursing mothers enrolling.
Despite having a lower CD4 count and higher rates of HIV progression, the HAART group was 80% less likely to develop TB than the people who did not receive HAART. Only nine cases of TB were diagnosed amongst those receiving HAART over the six years of the study, against 82 of the non-HAART group (2.4 vs 9.7 cases per 100 patient years, adjusted odds ratio 0.19 [95% CI 0.09-0.38; p3.
The protective effects of HAART were greatest for patients with more developed HIV disease and CD4 counts below 200 cells/mm3. The study authors suggest that the use of HAART could prevent 14-20 cases of TB per 100 patient-years of treatment. Limitations of the study include the high levels of latent TB prevalent in the local population from which the study participants were drawn.
In conclusion the authors note that their findings 'suggest that HIV-1 control is required for effective tuberculosis control, and that HAART can have a critical role in critical role in addressing the therapeutic nihilism surrounding the HIV-1 and tuberculosis co-epidemics in South Africa and other African countries.'
Julian Meldrum, International Editor of aidsmap.com commented: 'If a health service is struggling to provide adequate treatment for TB, its ability to deliver large-scale HAART must be questioned, even if it could afford the drugs. One reason for failure in this area may be that communities are demoralised when people with HIV develop other illnesses and die, despite successful treatment for TB. Sometimes even healthcare workers will question the value of what they are doing. This is what the authors mean by "therapeutic nihilism" and their argument is that attitudes will only change when there are real treatment options for people with HIV.'
Reference:
Motasim B et al. Effect of highly active antiretroviral therapy on incidence of tuberculosis in South Africa: a cohort study. The Lancet 359: 2059-2064, 2002.