HIV Patients on Antiretrovirals See Spike in Tuberculosis Rate

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HIV patients who received highly active antiretroviral therapy (HAART) therapy in rural South Africa, according to a new study, experienced as much as 5 times an increase in incidents of active tuberculosis.

HAART thereapy and the use of antiretrovirals  on a widespread basis has shown a marked reduction in new HIV cases in several countries in Africa. The rise in cases of TB are  indicative of a growing global health problem. They represent a significant barrier to the expansion of HIV/AIDS treatment programs in areas where TB is endemic.

According to Kogieleum Naidoo, MD, from the Centre for the AIDS Programme of Research in South Africa (CAPRISA):

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.”

Researchers believe that the spike in TB is because antiretroviral therapy can restore the immune-specific anti-TB response. This makes it easier for TB to develop soon after treatment with antiretrovirals starts.

After studying 969 consecutive HIV-infected patients who were started on treatment at CAPRISA in the mostly rural KwaZulu-Natal province of South Africa, Dr. Naidoo and colleagues found that a 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).

The guidelines of the South African National Antiretroviral Treatment Programe that were in effect at the time were used to determine HAART eligibility.

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.

Surprisingly, when patients with CD4 cell counts (CD4 cells or T-helper cells are a type of white blood cell that fights infection and their count indicates the stage of HIV or AIDS) in a patient.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).

TB incidence rates differed 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).

When is the best time to start up HAART in someone who has a TB diagnosis?

According to Andrew Kambugu, MBChB, MMed, from the Infectious Diseases Institute at Makerere University in Kampala, Uganda:

“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.”

Knowing a patient’s CD4 count is important, but Kambugu told Medscape Medical News that:

…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.”

Due to these problems, 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.”

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

Written by: Douglas Cobb

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