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DISCUSSION: Chemoprophylaxis in TB and HIV

Benefits and challenges of starting chemoprophylaxis of tuberculosis to HIV positive person

Several studies have now demonstrated that chemoprophylaxis is effective in preventing progression of TB infection in individuals dually infected with HIV and M. tuberculosis, although the efficacy is not 100 per cent (ranges from 60-90%). In addition, there is a suggestion that chemoprophylaxis may delay HIV disease progression amongst asymptomatic HIV infected individuals.

hiv infection

The increased risk of developing active disease associated with HIV infection has provoked a number of questions, like who should receive prophylactic therapy, how long to continue, whether isoniazid alone is the most effective agent, role of secondary prophylaxis monitoring for adherence and toxicity, etc.

Efficacy, cost effectiveness, and financial feasibility of such a chemoprophylaxis, in settings seen commonly in our country

Studies are being conducted to consider not just the efficacy but the feasibility and cost efficacy of preventive therapy in HIV infected people in countries with a high prevalence of TB. The unit cost to prevent future TB disease should be evaluated against the cost of successful treatment of TB cases under programme conditions. The need for and provision of preventive therapy should therefore depend on the HIV situation and local resources. The impact of preventive therapy on the prevalence of tuberculosis in HIV infected persons in contemporary sub-Saharan Africa showed that giving preventive therapy to 25 per cent of HIV-positive individuals with latent tuberculosis infection leads to a 3.9 per cent reduction in the prevalence of tuberculosis in 10 yr and a 5.1 per cent reduction in 20 yr. Doubling the preventive therapy coverage to 50 per cent approximately doubles the effect size, suggesting a linear relationship within the 20-yr period. This model-based analysis suggests that the impact of preventive therapy on tuberculosis in the population is likely to be small contrary to general belief.

Implementation of preventive therapy in India

In order to make an impact on the incidence of tuberculosis in India, preventive therapy has to be administered to a large number of people. Delivery of preventive therapy will be limited by the number of sites where a sufficient number of people know their HIV status, or where there is sufficient demand for and capacity of voluntary counselling and testing (VCT) services. Preventive therapy or chemoprophylaxis should therefore be promoted as an intervention for those living with HIV, rather than as a primary strategy to control the public health burden of tuberculosis.

Before a developing country can implement a preventive therapy programme, it should be able to readily identify HIV infected persons through counselling services and there should be good collaboration between the TB and AIDS programmes. Most importantly, preventive therapy should be organized and integrated into health services and the cost of prevention must be affordable or fully supported by state/district health service.

In India, collaboration between the National AIDS Control Programme (NACP) and Revised National Tuberculosis Control Programme (RNTCP) is being strengthened. All symptomatic persons diagnosed to have HIV infection VCT centers are referred to the nearest microscopy centre to rule out tuberculosis. In this setting, it would be feasible to offer preventive therapy to those individuals who are found not to have TB. Both isoniazid and cotrimoxazole prophylaxis can be given in the same clinic under close monitoring. If symptoms of TB develop at any time, patients can be promptly investigated and treated.

preventive therapy

In India, preventive therapy can be offered to HIV positive persons detected at VCT centers, who are referred to the nearest TB clinic. It should be included in the package of care for HIV positive persons, which would include ongoing counselling and provision of prophylaxis and treatment for opportunistic infections.

Chemoprophylaxis in TB and HIV-Experiences

I often discuss treatment of TB and HIV, with our students. We know that there is an increased risk of TB disease among those infected with both TB and HIV. However, to enrich our discussions, my group of students and me would like to have updates about the latest in the area of chemoprophylaxis for TB in an HIV patient. Therefore, I would like the AIDS Community members to inform us, in particular:

  • The benefits and challenges of starting chemoprophylaxis of tuberculosis to HIV positive person,
  • The efficacy, cost effectiveness, and financial feasibility of such a chemoprophylaxis, in settings seen commonly in our country, and
  • In India, must we recommend chemoprophylaxis with a course of anti-TB drugs to people infected with TB and HIV to prevent the reactivation of latent TB?
  • Dr. Neeti Goswami,
    Maulana Azad Medical College,
    New Delhi.

    In the context of this query of Chemoprophylaxis in TB and HIV, I have a few doubts.

    Given the burden of TB in India and the experiences that favour chemoprophylaxis of TB in PLHIV, a common doubt is in whom do we start chemoprophylaxis, that is, should it be for symptomatic patients, or should we be guided by CD4 counts as we do before starting ART. Once we decide to start the chemoprophylaxis the next doubt that confronts the practitioner is for how long do we give chemoprophylaxis? Moreover as seen, from the previous postings different authorities have come up with different recommendations for the drugs used in chemoprophylaxis. Hence, which drugs should be given or what criteria could help a practitioner make a choice of the correct drug or drugs in a particular PLHIV is also helpful. Herein, knowing the interaction of Rifampicin with ART, it would not be wise to give a Rifampicin containing regimen to PLHIV on ART. Moreover, we have to keep in mind that those studies that follow-up PLHIV for a short period of six months may not be adequate to prove the benefit or the lack of it.

    Dr. Janaki Menon,
    Department of Pediatrics,
    Medical College, Trissur, Kerala.

    We no more favour use of TB Chemoprophylaxis for HIV patients irrespective of Tuberculin skin test results. In fact we propose full course of anti TB drugs for HIV patient with reactive Tuberculin skin test, especially more than 10 mm x 10 mm.

    Our study between 2000 to 2004 convinced us regarding higher incidence of reactivation of TB in HIV patients following TB Chemoprophylaxis, namely, INH alone or Rifampicin plus INH or Rifampicin plus PZA (three arms study). The reactivation or relapse occurred within 6 to 12 months after TB chemoprophylaxis was stopped. I do not think cost is an issue for TB chemoprophylaxis in India. This observation similar to our study that minimum duration for anti TB drugs for HIV and TB co-infection (pulmonary TB) should be 9 months at least.

    Dr. J. K. Maniar,
    Consultant, Jaslok Hospital,

    The co-existence of TB and HIV is such a high level, that probably if intensive investigations are done before the start of ART therapy, most of the patients would be detected to have some form of active or latent tuberculosis, especially when the CD4 range is near that of 200-250. Using Isoniazid as a single agent could lead to Isoniazid resistance which again could seriously mess up the TB therapy at a later stage. We have found that majority of PLHIV develop TB infections when their CD4 range is somewhere around 300. So, I would suggest that in the Indian scenario, it would be better to start ART when the CD4 count is in the range of 300-350 as we can avoid TB and other OI's.

    Dr. Ashok Mewara,
    Reliance ART Center, Surat.