A TB diagnosis during the first 12 months of antiretroviral therapy (ART) independently doubled the risk that patients at a South African HIV clinic would not gain at least 50 CD4 cells/μL during the first 6 months of therapy, according to results of a retrospective cohort study.
CD4 counts do not rise adequately during the first months of ART in some patients starting their first antiretroviral combination. In South Africa and other sub-Saharan countries, HIV and TB are coepidemic diseases. To determine whether a new TB diagnosis affects CD4 gains early in the course of ART, researchers at the Stellenbosch University HIV clinic and US collaborators undertook this study.
This retrospective analysis involved 691 patients starting ART between January 2004 and May 2008. Median age of study participants was 35 (interquartile range [IQR] 30 to 42), two thirds (66%) were women, and median pretreatment CD4 count and viral load were 122 cells/μL (IQR 59 to 173) and 5.35 log10 copies/mL (IQR 4.85 to 5.81).
While 179 people (26%) had TB when they started ART, TB developed in 49 people (7%) during the first 12 months of ART. Twenty percent of the study group—141 people—had a suboptimal CD4 response, defined as gaining fewer than 50 cells/μL during the first 6 months of therapy.
Among people with newly diagnosed TB during the first year of ART, 17 of 49 (35%) had a suboptimal CD4 response, compared with 104 of 478 (22%) who had no evidence of TB.
Statistical analysis adjusted for age, gender, pretreatment CD4 count, and detectable viral load determined that people with newly diagnosed TB had more than a doubled risk of a poor CD4 response (odds ratio [OR] 2.20, 95% confidence interval [CI] 1.14 to 4.24, P = 0.021). A detectable viral load between treatment months 6 and 12 doubled the risk of a poor CD4 response (OR 2.01, 95% CI 1.03 to 3.9, P = 0.046). Female gender did not independently affect the risk of a sluggish CD4 gain.
The researchers caution that because of the retrospective nature of this study, the results do not say whether TB caused the low CD4 gains or the low CD4 gains caused the TB. Still, they believe their findings “provide additional support for the initiation of ART at higher CD4 counts.”
Source: Ingrid Eshun-Wilson, Jantjie J. Taljaard, Jean B. Nachega. Sub-optimal CD4 T-lymphocyte responses among HIV infected patients who develop TB during the first year of ART. Journal of AIDS & Clinical Research. 2012; 3: 135.
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