Strategy for HIV antibody testing in TB patients which tests to use and when to use them

In general, WHO recommends different HIV testing strategies, depending on the objective of testing.The aim is to maximize accuracy and minimize cost. The table below shows the strategy appropriate for each objective of testing.

Objectives, strategies and interpretation of HIV tests

Objective

Testing strategy

Interpretation of result

Individual patient management

Test sample with EIA or simple/rapid assay

1st assay negative = patient HIV negative or test to be repeated

1st assay positive + 2nd assay positive = patient HIV-positive

1st assay positive and 2nd assay negative —► repeat both assays

Results remain discordant —►

repeat sample and testing

Surveillance (in population with HIV prevalence > 10%)

Test sample with EIA or simple/rapid assay

Assay negative = patient HIV-negative

Assay positive = patient HIV-positive

6.2.5 Diagnosis of HIV infection in individual TB patients

The link between HIV and TB is well known to many members of the public. Patients with TB may therefore be well aware of the possibility of HIV coinfection. It is important to offer counselling and voluntary HIV testing, if available, to TB patients. Possible benefits include:

a) patients may want the chance to know their HIV status;

b) better diagnosis and management of other HIV-related illnesses;

c) avoidance of drugs associated with a high risk of side-effects;

d) increased condom use and decreased HIV transmission;

e) possible use of chemoprophylaxis with cotrimoxazole to prevent opportunistic infections and reduce mortality;

f) possible use of ART for HIV;

g) the opportunity to counsel patients and relatives about HIV infection and about the prognosis;

h) the opportunity to advise patients and relatives about measures to prevent further HIV transmission.

It is preferable to have same-day HIV testing using rapid test kits as this minimizes the number of visits to counselling and testing centres. The other important issue for clients is confidentiality.

PRACTICAL POINT

Anti-TB drug treatment is the same for HIV-positive and HIV-negative TB patients, with one exception: do not give thioacetazone to HIV-positive TB patients (increased risk of severe and sometimes fatal skin reactions).

A policy of compulsory HIV testing of TB patients (even if this were legal) would be counterproductive. This type of policy would have the following results:

a) patients would be deterred from seeking care;

b) there would be decreased case-finding in at-risk groups;

c) the credibility of health services would be reduced.

HIV COUNSELLING

HIV voluntary counselling and testing (VCT) starts with counselling of individuals to enable them to make an informed choice about HIV testing.This decision is entirely the choice of the individual, who must be assured that the process will be confidential. Confidential counselling is essential before and after HIV antibody testing. Individuals give explicit informed consent to have the test. This means that they understand what the test involves and the implications of testing. The counsellor provides support. Counselling is a dialogue between the individual and the counsellor.

Counsellors

With suitable training, anyone who works with patients and families can be a counsellor. Counsellors may be members of the community or health workers. For sustainability of VCT services, counsellors need support and supervision. Many health workers have had counselling training. In the course of their duties they have the opportunity to counsel patients for HIV testing. Doctors and other clinicians are often in a good position to counsel patients for HIV testing. This is because clinicians have already established a relationship with the patient, who usually trusts the clinician.

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