3rd vs 4th generation HIV testing: almost half of UK clinics out of step with national guidelines

Simon Collins, HIV i-Base

In 2011, prompted by calls to the i-Base phoneline reporting wide diversity in the information given to people contacting GUM clinics for HIV testing, i-Base wanted to understand why this was often different to UK guidelines.

Although 4th generation HIV tests are recommended at four weeks post exposure, many people were still being advised to wait for three months.

Results from the prospective community survey of 112 randomly selected GUM clinics that was then undertaken, were presented by Emma Rezel from the London School of Hygiene and Tropical Medicine, in an oral presentation at BHIVA. [1]

A mystery patient scenario was used to conduct a semi-structured questionnaire at the point of contact or a contact the caller was immediately forwarded on to. This was to mimic the reality of advice and information made available in a natural situation to a member of the public calling a clinic with queries about HIV testing.

In response to the question “Is it a third or fourth generation test?” 40% of clinics stated it was a 4th generation test, 6% gave some indication that it was a 4th generation test, for example, mentioning that it could detect the presence of an antigen, 4% stated or gave some indication that they used a 3rd generation test, 2% stated they used both, 1% said they used a PCR test. However, 31% didn’t know, 8% gave an inaccurate or unclear response, and 8% didn’t answer.

Responses to the question “How accurate are the results and when should I come and get tested?'” were equally mixed with only 24% of clinics mentioning the accuracy of fourth generation tests at 4 weeks post exposure and 36% only referring to accuracy at 12 weeks suggesting 3rd rather than 4th generation testing procedures were being referred to.

Although nearly all clinics mentioned the need for the caller to come into the clinic, only 41% were sensitive and non-judgmental and put the service-user at ease, providing responses:

“There’s no need to be anxious. A nurse will answer all your questions if you go in for an appointment.”

“Even if he was positive, it depends on various factors, like, if he’s on treatment and if there’s blood-to-blood transmission. HIV is hard to catch so don’t worry”.

By contrast, 13% of clinics scored particularly poorly in terms of sensitivity to the anxieties of the caller provide confusing or unsympathetic responses:

“We don’t understand it all so I doubt you will either.”

“If you don’t know much about him, why did you have unprotected sex with him?”

“We only see positive tests amongst heterosexuals who have sex with someone from Africa.”

“If you’re not prepared for a positive result, don’t come in for a test.”

While these examples produced some of the few lighter moments during the conference, the implications of these findings was not lost on many attendees, especially given that an earlier BHIVA audit reported 4th generation tests being used by 95% of clinics that responded.

The i-Base study found no difference between geographical location of clinics (London vs out of London) but did find a statistically significantly better responses when callers were able to speak to a doctor, nurse or health advisor rather than an administrator or receptionist, suggesting that some degree of retraining be developed for anyone taking direct calls from members of the public.

In response to this issue, i-Base have produced a new non-technical guide to HIV testing and the risk of sexual transmission, free to order for UK clinics. [2]

BASHH statement on the window period (March 2010)

  • HIV testing using the latest (4th generation) tests are recommended in the BHIVA/BASHH/BIS UK guidelines for HIV testing (2008).
  • These assays test for HIV antibodies and p24 antigen simultaneously. They will detect the great majority of individuals who have been infected with HIV at one month (4 weeks) after specific exposure.
  • Patients attending for HIV testing who identify a specific risk occurring more that 4 weeks previously, should not be made to wait 3 months (12 weeks) before HIV testing.
  • They should be offered a 4th generation laboratory HIV test and advised that a negative result at 4 weeks post exposure is very reassuring/highly likely to exclude HIV infection.
  • An additional HIV test should be offered to all persons at 3 months (12 weeks) to definitively exclude HIV infection. Patients at lower risk may opt to wait until 3 months to avoid the need for HIV testing twice.


  1. Rezel E. 4th generation (Ag/Ab) HIV testing: 47% of clinics contradict current guidelines. 18th BHIVA Conference, 18-20 April 2012, Birmingham. Oral abstract O21.
    View slides (PDF).
    View webcast.
  2. HIV i-Base. HIV testing and risks of sexual transmission. (February 2012).

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