Results of tests for recent HIV infection can be safely given to patients

Results from the Recent Infection Testing Algorithm (RITA) can be discussed with newly-diagnosed patients, UK clinicians say. Although RITA was designed for use in monitoring at a population level and does not give consistently accurate results to individuals, sharing the results with patients has not led to any adverse outcomes, officials from the Health Protection Agency report in an article published online ahead of print in HIV Medicine.

The Recent Infection Testing Algorithm (RITA) is a generic name for a number of laboratory techniques which distinguish recent and established HIV infection. They are sometimes also known as incidence tests or as STARHS (Serological Testing Algorithm for Recent HIV Seroconversion).

The approaches depend on looking for specific antibody markers, which give different results in the months following infection. If a test gives a result below a pre-determined cut-off point, it is deemed to be an infection that probably occurred in the last six months.

Incidence tests were designed to help public health officials monitor the number of new HIV infections in a community, in order to better inform HIV prevention work. Results from RITA have shown high rates of recent infection in gay men and in heterosexual young people.

Because of person-to-person variability in the development of immune response, the tests are seen as being unable to give a definitive date for an individual’s infection. They are only able to suggest rough timings, and have a considerable margin of error.

Specifically, results may be inaccurate when a person does not have the most common HIV-1 subtype (B). Moreover some people may be misclassified as having recent infection when they have a low CD4 cell count or when they have taken antiretroviral drugs, either as treatment, post-exposure prophylaxis or pre-exposure prophylaxis.

For these reasons, other countries which use RITA testing for public health purposes do not return the results to individual patients. One specific concern is that some newly diagnosed individuals could be led to have an unwarranted certainty about when they were infected (and by whom). In the context of the criminalisation of HIV transmission, police and prosecutors have been urged to interpret RITA results with caution and only alongside other evidence, such as phylogenetic analysis, CD4 count, viral load, HIV testing history and sexual history.

RITA has been used in the UK since 2009, with over 4000 samples from 90 different clinics having been tested. Results are returned to the laboratory which conducted HIV testing. At the clinician’s discretion, results may be discussed with the patient. Clinicians are encouraged to explain the limitations of the test and to present the results in the context of the patient’s clinical and behavioural history.

Impact of discussing test results

Health Protection Agency officials surveyed clinicians involved in RITA testing, with 42 responding. The majority of respondents (69%) had managed at least ten patients who had a RITA result. Most respondents said that the test was now a standard part of the care for a newly-diagnosed patient, without consent being specifically requested.

While nine out of ten respondents had discussed RITA results with patients, they did not do so universally. They were particularly likely to do so in the context of a possible seroconversion illness or when discussing starting treatment with a person whose CD4 cell count was around 350 cells/mm³.

Nine out of ten respondents stated that discussing RITA results with patients would help with contact tracing – specifically, by more confidently restricting contact tracing to a specific timeframe and by prioritizing patients with a probable recent infection.

While a third of clinicians had previously had concerns about the information adding to patient anxiety, this had not occurred in practice. Clinicians described the response from patients on learning about the estimated timing of their infection as overwhelmingly positive or neutral.

No adverse events as a result of returning the RITA result to a patient were reported by the respondents. So far, RITA results have not been used as evidence in criminal proceedings.