Currently in the UK it is estimated that 24%, approximately 22 200 individuals, are unaware of their HIV infection . These data are derived from statistical modelling of many surveillance, and survey-based data sources. One of the surveillance programmes used is the unlinked anonymous HIV seroprevalence survey, the GUMAnon Survey, where patients who have blood taken at a sexually health clinic would in addition give an additional sample which is tested for HIV after the sample is completely anonymised. The limited information accompanying the sample includes whether the person is known to be HIV positive, has a test in the clinic or refuses an HIV test.
A recent study published in the journal Sexually Transmitted Infections (STI) attempted to identify HIV-infected individuals who attend a genitourinary clinics in the UK aware of their HIV status but fail to tell the clinic they are infected, or on treatment. In this study in addition to anonymised HIV testing the positive samples had viral load (VL) estimation and after excluding known HIV positives the remaining the samples were analysed for the presence of a panel of antiretroviral drugs.
The authors identified 130 individuals attending a single London sexually transmitted infection clinic in 2009 who refused an HIV test. Of 28 patients identified by the anonymised test as being HIV positive who had not admitted to being infected 10 patients underwent a test at the clinic and received a positive test.
The other 18 had refused an HIV test, although found to be positive by the anonymised test. Thirteen of these (72%, 95% CI: 47% to 90%) had a blood viral load (VL) below detection level (n=11) or VL <1000 copies/ml (n=2) suggesting they were on antiretroviral treatment. Eight had sufficient blood to undergo antiretroviral testing, and all were positive for the presence of drug; all with therapeutic levels of clinically appropriate combinations.
Thus nearly three quarters of HIV positive patients (72%) who refused an HIV test, and hence would have been considered as not knowing their HIV status, were indeed aware of their status and are on treatment.
These results “presents a number of challenges and dilemmas both for clinics and surveillance systems” says Jackie Cassell, editor of STI journal, who went on to also points out the difficult issues of confidentiality in sexual health services in the age of electronic health records.