Rapid HIV testing — better or just faster?

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SummaryPractice pointsFirst point-of-care test available in AustraliaBetter late than never, or is it?How do rapid tests compare overall?Focus on acute HIV infectionSupport in principle and policyIf HIV testing is the gateway, rapid tests open the doorFor more informationReferences


The TGA recently registered a rapid HIV test as the first point-of-care test for preliminary screening for HIV infection. One in four people with HIV are diagnosed by a GP who has never diagnosed HIV before. The new test is seen as a way to expand the reach and accessibility to HIV testing since it can be administered by health professionals within the timeframe of a typical consultation. Special training and participation in a quality assurance program are required. The test detects both HIV antibodies and the p24 antigen however all reactive tests require confirmation by a diagnostic laboratory test. Currently, rapid testing is not widely available in Australia and can only be accessed at centres participating in clinical trials. These studies will inform quality assurance and guidelines for broader use in community and primary care settings.

Practice points

  • In patients with mild-to-severe flu-like illness, clinical features that should alert to the possibility of acute HIV infection include ‘glandular fever–like’ illness, meningeal involvement, recent sexually transmissible infection and/or transient neurological symptoms.1
  • When a patient reports a high-risk exposure to HIV, immediate referral to an antiretroviral prescriber, sexual health centre or hospital emergency department is necessary to access non-occupational post-exposure prophylaxis.1
  • Currently a combined HIV antibody and p24 antigen test is the most common diagnostic test for suspected acute HIV infection.2,3 The introduction of rapid HIV testing is not expected to change this except in targeted primary care settings that service high-risk individuals.
  • The rapid test recently approved for point-of-care use may be considered for screening in high-risk populations (e.g. men who have sex with men) or hard to reach populations and individuals but are not recommended for use in remote communities.4
  • The new test has a low positive predictive value that leads to false positives in settings with low HIV prevalence; supplementary laboratory testing is required to confirm a reactive (positive) test result, particularly in the period before HIV antibodies appear.4
  • Guidelines for the appropriate use of these point-of-care tests in primary care and recommendations regarding where, by and in whom the test should be conducted are currently lacking but under review.

First point-of-care test available in Australia

Late in 2012 the TGA registered a new generation rapid HIV test as the first point-of-care test for preliminary screening of HIV antibodies and antigen.5 The test can be performed by health professionals who participate in an HIV point-of-care quality assurance program.5

1 in 4 people living with aids are diagnosed by a GP who has not previously diagnosed HIV6

Currently the gold standard test is a fourth generation enzyme immunoassay (referred to as an ELISA) to detect for HIV antibodies and the p24 antigen, and testing should include a supplemental assay to retest all reactive samples.2,3 Previously, in Australia rapid HIV tests were only registered by the TGA for use as a supplemental test in diagnostic or confirmatory testing strategies in a laboratory but not for use as a standard screening test at the point-of-care.4

Better late than never, or is it?

In 2004, the WHO published guidelines for rapid HIV testing and counselling.7 These tests have been in use in many developed and developing countries for over a decade with positive impact on HIV testing rates especially in people with a high risk of infection who have never been tested.8

Nevertheless, the rollout of the first point-of-care test in Australia has met with some debate,9 confusion about appropriate implementation,10 and quality assurance concerns.11 While the Queensland Department of Health announced free testing would be rolled out as part of regular clinical practice,12 the Commonwealth announced $1.3 M in funding to investigate how point-of-care testing can best be used as a complement to existing testing for HIV.13

How do rapid tests compare overall?

Operational strengths and advantages

Decentralisation of HIV testing and counselling is seen as a key advantage for rapid point-of-care testing (for other strengths, see Table 1) as it reduces the reliance on laboratory services,7 and expands the reach of testing to the point of care and community sites (including mobile testing) and homes.14

Table 1: Strengths of rapid HIV tests7

Specimen type Whole blood (finger-prick sampling) allows for ease of collection but can also use serum or plasma
Little laboratory equipment required Small sample volume avoids the need for centrifugation
No electricity or water supply required
Easy to perform with minimal waste and waste disposal required Little technical training required
Few steps
Easy to interpret Visual interpretation of results, usually without equipment
Stable end-point reading
Rapid Results available in < 30 minutes
Easy to store Storage at room temperature for several weeks
12 months or longer shelf life
Number of tests performed Suitable for individual and small volume testing, e.g. 1 to 40 samples per day

More on performance and accuracy

What defines accuracy in a diagnostic test?

The accuracy of a diagnostic test describes how well it identifies people with and without the disease based on:

  • sensitivity – a test with high sensitivity is more likely to correctly identify individuals who do not have the disease (e.g. without HIV infection).
  • specificity – a test with high specificity is more likely to correctly identify individuals who have the disease (e.g. with HIV infection).
  • positive predictive value (PPV) –  the extent to which being categorised as positive predicts the presence of disease (e.g. infected).
  • negative predictive value (NPV) – the proportion of people with a negative test result who do not have the disease (e.g. uninfected).

Remember, no test is 100% sensitive and 100% specific.

There is substantial evidence from studies in many countries that the sensitivity and specificity of rapid tests are similar to those of the standard ELISA.7

Although, in settings with a low HIV prevalence (e.g. < 1%), even a test with high sensitivity and specificity may not have a sufficient PPV; meaning there is a higher chance of obtaining a false-positive result. As prevalence of HIV increases, the proportion of false positives decreases but the probability of false negatives increases (Table 2).7

Table 2: Positive and negative predictive values depending on HIV prevalenceA

HIV prevalenceB 0.1% 1% 5% 10% 30%
NPV single test 100% 100% 99.9% 99.9% 99.6%
PPV single test 9% 50% 84% 92% 98%
PPV two tests 91% 99% 99.8% 99.9% 100%
A. Diagnosed using a rapid test and assuming 99% sensitivity and 99% specificity.

B. The UNAIDS HIV estimates for 2011 indicate a prevalence of between 0.1% to 0.2% in Australian adults (aged 15 to 49 years).15

Important limitations of rapid tests

In preparation for the arrival of rapid point-of-care HIV testing in Australia, the National HIV Testing Policy outlined the limitations of rapid testing:4

  • Rapid point-of-care tests function as tests for screening rather than definitive diagnosis.
  • There is a need to confirm reactive test results (although a high negative-predictive value means negative tests are correctly identified).
  • The tests require a longer time window after an HIV exposure to detect infection (Table 3).

Table 3: HIV testing assays and their time window.16

HIV test  Infection detected Seroconversion window
First-generation ELISA HIV antibodies 35–45 days
Second-generation ELISA
(including most rapid tests)
HIV antibodies
25–35 days
Third-generation ELISA
(including some rapid tests)
HIV antibodies 20–30 days
Fourth-generation ELISA HIV antibodies and p24 antigen 15–20 days
Nucleic acid amplification HIV nucleic acids 10–15 days

Focus on acute HIV infection

Early diagnosis, monitoring and treatment of patients with recently acquired HIV infection may alter the long-term course.1 The onset of symptoms often coincides with the appearance of HIV antibodies at about 10 to 14 days but the person may test negative for HIV antibody by ELISA for up to three weeks after the onset of symptoms.1 Thus identification of acute HIV infection requires detection of HIV nucleic acids or p24 antigens.17 Currently the earliest time at which HIV nucleic acids can be detected after infection is about 10 days, and it is another 10 days before antibodies appear (Table 3).16 However, nucleic acid amplification is generally not recommended to diagnose acute HIV infection due to a reported low false-positive rate in the acute setting.1

Individuals with acute HIV infection have been shown to be more infectious compared with individuals who have a chronic infection.18 HIV transmission studies have shown higher sexual transmission rates during acute and early infection compared with latent or chronic infection.19,20 Thus, early identification of HIV infection is important to prevent transmission to negative partners.

Poor detection of acute HIV

The development of rapid point-of-care HIV tests improves turnaround times and the ability to provide results to more people but this occurs at a cost with low sensitivity during the period before HIV antibodies appear.21 The TGA-approved combined rapid test (Combo RT) allows for simultaneous detection of the HIV p24 antigen as well as antibodies to both HIV-1 and HIV-2 infection.5 A recent analysis of the Combo RT found that while it accurately detects HIV antibodies present in established HIV infection, the test does not perform well in detecting the p24 antigen in acute HIV infection.17 Other studies have confirmed low rates of p24 antigen detection using this test.22

Overall, rapid point-of-care tests such as the Combo RT are a useful screen for reactive results but supplemental testing is still required to confirm the presence of HIV antibodies or nucleic acids.16

Support in principle and policy

A national HIV testing priority

A decline in the frequency of HIV testing is emerging in Australia, accompanied by a steady increase in new HIV diagnoses every year since 1999; there was an 8.2% increase in the number of new HIV diagnoses in 2011 compared with 2010.23 Introduction of rapid HIV testing into communities that have high HIV prevalence is listed as a national HIV diagnosis and testing priority.6 The latest NSW HIV Strategy 2012–2015 also reaffirmed support for the use of rapid HIV testing and recognised the local policy implications from overseas licensing of self-administered rapid HIV testing for over-the-counter sale in the US.24 Home-based testing is currently not supported in Australia.4

Melbourne Declaration

Australia has committed to halving rates of HIV infection by 2015 and the need to substantially increase access to and uptake of voluntary HIV testing was identified as a priority action of the Melbourne Declaration.25 With respect to rapid HIV testing, the following actions are highlighted:25

  • Make rapid HIV testing widely available in clinical and community settings.
  • Set up rapid HIV testing access programs.
  • Investigate options to make rapid HIV tests available for home use with links to screening for sexually transmitted infections.

If HIV testing is the gateway, rapid tests open the door

HIV testing and counselling is recognised as the gateway to HIV/AIDS prevention, care, and treatment — rapid HIV diagnostic tests in point-of-care settings has been identified by the WHO as an important strategy to expand access, increase the return of results and enable appropriate referral and follow-up.26

The importance of knowing

It is estimated that half of all people living with AIDS globally are unaware of their HIV status.27 While in Australia HIV testing rates are high, recent data suggest 10–20% of Australians living with HIV have not yet been diagnosed,4 and based on a small sample of gay men, as many as 30% may not know their HIV status.28

Two thirds of newly diagnosed infections in Australia are transmitted through sexual contact between men,23 and a recent study among gay men in NSW found testing was delayed or avoided because of the slowness of obtaining results.29 Studies in Australia show that anywhere from 20% to 50% of people do not return to collect their HIV results;30,31 there is strong evidence that people are substantially more likely to receive their HIV status with rapid testing than with conventional tests that require a longer waiting period or a return visit to obtain the result.32

Reducing late diagnosis

Delays in testing and poor links between testing and treatment uptake, lead many people to start treatment when they are significantly immunocompromised. This results in poor outcomes and ongoing HIV transmission.26 In Australia, late diagnosis of HIV is disproportionately represented in those with HIV-associated mortality and morbidity,4 and more likely to be made by GPs.24The highest number of late diagnoses of HIV is among men who have sex with men, including those who also inject drugs.24 Improving access to, and uptake of, testing is important to reduce late diagnosis of HIV.6

For more information

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