8. Tuberculosis in patients already receiving ART

There are two issues to consider in patients who are diagnosed with TB while on ART. The first concerns modifications of ART regimen, required in some circumstances to allow co-administration with TB treatment.

In the table below you will find the ART recommendations for patients, who develop TB after starting a first-line or second-line ART regimen:

 

 

The second issue is whether the presentation of active TB on ART constitutes ART failure. In cohort studies, ART decreases the incidence of TB in treated patients by approximately 80%. Rates of TB among treated patients nevertheless remain persistently higher than among HIV-negative individuals. 


 
Adapted from Lawn et al. Burden of tuberculosis in an antiretroviral treatment programme in sub-Saharan Africa: impact on treatment outcomes and implications for tuberculosis control. AIDS 2006:20.  

An episode of TB can occur across a wide range of CD4 cell counts and does not necessarily mean that the patient’s ART is failing. Before switching to a second line regimen more factors need to be taken into account.

In addition, in the first 6 months after the initiation of ART subclinical or previously undiagnosed TB often presents (unmasking type).

WHO therefore recommends that the following principles be applied when determining whether the development of TB on ART constitutes treatment failure:
  • If an episode of TB occurs during the first six months following the initiation of ART, this should not be considered a treatment failure event and the ART regimen should be adjusted for co-administration with rifampicin-containing regimens.
  • If an episode of TB develops more than six months after the initiation of ART  the decision about whether the TB diagnosis represents ART failure is based on the CD4 cell count and, if available, the viral load.
  • If a CD4 cell count is not available the decision on whether the TB diagnosis indicates an ART failure depends on whether the TB is pulmonary or extrapulmonary and whether there are other non-TB stage 3 or 4 events.
  • While awaiting more data, WHO recommends that the development of an episode of pulmonary TB after six months of ART, without other clinical and/or immunological evidence (CD4) of disease progression, should not be regarded as representing ART failure.
  • Extrapulmonary TB should be considered as indicating ART failure, regardless of the CD4 count, although simple lymph node TB or uncomplicated pleural disease may be less significant than disseminated TB. If there is a good response to TB therapy the decision to switch to a second-line regimen can be delayed until short-course TB therapy has been completed.

Especially because it is a nightmare to combine second-line ART with anti-tuberculosis treatment