HIV viral load as an independent risk factor for tuberculosis in South Africa : collaborative analysis of cohort studies
Date
2017
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley Open Access
Abstract
Introduction: Chronic immune activation due to ongoing HIV replication may lead to impaired immune responses against
opportunistic infections such as tuberculosis (TB). We studied the role of HIV replication as a risk factor for incident TB after
starting antiretroviral therapy (ART).
Methods: We included all HIV-positive adult patients ( 16 years) in care between 2000 and 2014 at three ART programmes
in South Africa. Patients with previous TB were excluded. Missing CD4 cell counts and HIV-RNA viral loads at ART start
(baseline) and during follow-up were imputed. We used parametric survival models to assess TB incidence (pulmonary and
extrapulmonary) by CD4 cell and HIV-RNA levels, and estimated the rate ratios for TB by including age, sex, baseline viral
loads, CD4 cell counts, and WHO clinical stage in the model. We also used Poisson general additive regression models with
time-updated CD4 and HIV-RNA values, adjusting for age and sex.
Results: We included 44,260 patients with a median follow-up time of 2.7 years (interquartile range [IQR] 1.0–5.0); 3,819
incident TB cases were recorded (8.6%). At baseline, the median age was 34 years (IQR 28–41); 30,675 patients (69.3%) were
female. The median CD4 cell count was 156 cells/μL (IQR 79–229) and the median HIV-RNA viral load 58,000 copies/mL (IQR
6,000–240,000). Overall TB incidence was 26.2/1,000 person-years (95% confidence interval [CI] 25.3–27.0). Compared to the
lowest viral load category (0–999 copies/mL), the adjusted rate ratio for TB was 1.41 (95% CI 1.15–1.75, p < 0.001) in the highest
group (>10,000 copies/mL). Time-updated analyses for CD4/HIV-RNA confirmed the association of viral load with the risk for TB.
Conclusions: Our results indicate that ongoing HIV replication is an important risk factor for TB, regardless of CD4 cell counts,
and underline the importance of early ART start and retention on ART.
Description
CITATION: Fenner, L., et al. 2017. HIV viral load as an independent risk factor for tuberculosis in South Africa : collaborative analysis of cohort studies. Journal of the International AIDS Society, 20(1):21327, doi:10.7448/IAS.20.1.21327.
The original publication is available at https://onlinelibrary.wiley.com
The original publication is available at https://onlinelibrary.wiley.com
Keywords
HIV-positive persons, HIV (Viruses), Tuberculosis
Citation
Fenner, L., et al. 2017. HIV viral load as an independent risk factor for tuberculosis in South Africa : collaborative analysis of cohort studies. Journal of the International AIDS Society, 20(1):21327, doi:10.7448/IAS.20.1.21327