Neil Canavan

July 12, 2013

KUALA LUMPUR, Malaysia — The incidence of active tuberculosis (TB) infection increased as much as 5 times for HIV-infected patients who received highly active antiretroviral therapy (HAART) therapy in rural South Africa, according to a new study.

This finding is indicative of a growing global health problem, and represents a significant barrier to the expansion of HIV/AIDS treatment programs in areas where TB is endemic.

"The challenge of unmasking TB in rural patients accessing HAART services in areas where the HIV and TB burdens are high, particularly where diagnostic tools and access to clinical care are limited, has not been fully quantified," said Kogieleum Naidoo, MD, from the Centre for the AIDS Programme of Research in South Africa (CAPRISA).

Because antiretroviral therapy can restore the immune-specific anti-TB response, TB can develop soon after treatment starts.

To assess the scope of the problem, Dr. Naidoo and colleagues studied a large cohort of HIV patients in the mostly rural KwaZulu-Natal province of South Africa.

Dr. Naidoo presented the findings here at the 7th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention.

Too many clinicians in the developing world don't have access to a CD4 count to make the decision.

This prospective study followed 969 consecutive HIV-infected patients who were started on treatment at CAPRISA. The guidelines of the South African National Antiretroviral Treatment Programme that were in effect at the time were used to determine HAART eligibility.

At total of 173 (17%) HIV-infected patients had active TB at treatment initiation. The incidence rates of TB were roughly 3 times higher in the first 3 months of treatment than in months 4 to 24 of treatment (11.5 vs 3.2 per 100 person-years; P < .001).

Surprisingly, when patients with CD4 cell counts below 50 cells/mm³ at treatment initiation were compared with patients with CD4 cell counts above 200 cells/mm³, immune status did not appear to have an impact on TB incidence rates (P = .81).

However, TB incidence rates did differ by sex and age. The incidence rate of unmasked TB was almost 2 times higher in females than in males (13.3 vs. 7.3 per 100 person-years; P = .21), and almost 5 times higher in patients 24 to 34 years of age than in those 35 years and older (17.8 vs 3.8 per 100 person-years; P = .01).

In addition, TB status had a negative impact on HIV/AIDS disease management. The rebound of CD4 counts after 12 months of treatment was significantly different in patients with unmasked TB than in those with incident TB (P = .03).

Lacking Resources

"There is some subtlety about when to start HAART in someone who has a TB diagnosis. The evidence shows that this is quite dependant on the CD4 count when you want to start," said Andrew Kambugu, MBChB, MMed, from the Infectious Diseases Institute at Makerere University in Kampala, Uganda.

However, "too many clinicians in the developing world don't have access to a CD4 count to make the decision and, even when you have a CD4 count, there is physician discretion on when to actually start," he told Medscape Medical News.

Because of this, new guidelines wouldn't necessarily help. "The issue is that the tools you need to follow the guidelines are limited," he explained. "What there needs to be is more funding."

Dr. Naidoo and Dr. Kambugu have disclosed no relevant financial relationships.

7th International AIDS Society (IAS) Conference on HIV Pathogenesis, Treatment and Prevention: Abstract TUPDB0101. Presented July 2, 2013.


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