Understanding HIV Testing: Insights from Australian Prescriber Podcast

Welcome to the Australian Prescriber Podcast. An independent, no-nonsense podcast for busy health professionals. Hi, and welcome to this Australian Prescriber Podcast. And today we're going to be talking about HIV [human immunodeficiency virus] testing. I'm Dr. Justin Coleman, a GP in Inala Indigenous Health in Brisbane. And with me, I have a veritable expert on the matter of testing for HIV, and that is Louise Owen. Louise Owen is clinical professor at the Statewide Sexual Health Service at Tasmanian Health Service, and also the president of the Australian Chapter of Sexual Health Medicine. Welcome to our humble podcast, Louise. Thank you very much, Justin. Thank you for having me, and I look forward to our chat. Thank you. And I very much enjoyed reading your article in Australian Prescriber, Testing for Human Immunodeficiency Virus. One thing was just to keep up with the stats in Australia. So to quote from your article, there's about 30,000 people currently in Australia living with HIV as a recent stat. And there were 757 new diagnoses in 2024. Although over the past decade, there's been a very welcome decline in overall new HIV diagnoses. It's declined by around about a quarter. And you mentioned in the article that, in particular, that reduction is largely among gay, bisexual, and other men who have sex with men. What do you put the decline down to, and does that alter what we do in terms of testing? Well, we know that testing is important, that people are aware of their status, so that those people diagnosed with HIV can be linked to care. And in Australia, we have a really good cascade of care where we think that probably 92% of people living with HIV are actually aware of their status, and 97% of those are on treatment, and 98% of them have an undetectable viral load. So we're testing to detect cases so that we can get people into care and reduce onward transmission. So the great news about the decline in HIV diagnoses each year is related to our excellent responses in the prevention space particularly, and that is the rollout of PrEP or pre-exposure HIV prophylaxis. And that has been widely taken up in Australia with initial demonstration projects and now on the PBS [Pharmaceutical Benefits Scheme] available for GPs to prescribe, and also available for Medicare-ineligible patients either through their GPs, through online providers, or sexual health services. And there's a wonderful new initiative rolling out at the moment with some increased federal funding to particularly target Medicare-ineligible people who may be at risk of HIV acquisition for them to access PrEP across Australia. So those things have really helped the decline in HIV diagnoses and also people on active treatment with antiretroviral therapy who have an undetectable viral load have no risk of transmitting the virus sexually. And so we have treatment as prevention as well. Undetectable equals untransmissible. I think that's a wonderful phrase you also mentioned in the article. So we're not going to look at the treatment any further during this particular podcast. So we're really looking at those 8% of people you mentioned living with HIV in Australia who are unaware of their HIV status and ways in which we can cut that number down and detect that. But without the universal testing, which is applied in some other countries based upon a higher prevalence of HIV. So we're going to talk about where to concentrate our testing with a view that if you get this early, it really does make a difference because the early initiation of the therapy gives almost no drop in life expectancy compared to those without HIV. Yes, that's right, Justin. But unfortunately, a number of the diagnoses in the last statistics of 757 new ones, a considerable number of those were late diagnoses. So that means the person is likely to had HIV for some time, have a decreased CD4 count, the immune cell count, and often have had a number of medical conditions relating to that whilst not perhaps AIDS-defining illnesses. And so yes, there's a significant health impact and public health impact and health cost to that undiagnosed HIV case. So our testing push is towards elimination of HIV transmission, and if people are aware of their status, we can impact on that. And the current HIV task force led by the Minister for Health is looking at that and all the different ways that we can impact on that. Okay. So looking at that 8% of people who potentially we need to be finding out whether they have HIV, let's look at what populations we should be testing, given it's not universal. The first one in Australia is antenatal screening. That's universal during the antenatal period, and that's standardised cross Australia. All guidelines recommend that. The second big category is during STI [sexually transmissible infection] screening. Can you just talk to me about that? If I can just add, Justin, of course, we're adding the syphilis test for the antenatal population and at least 3 tests for all pregnancies and sometimes more in areas of high syphilis prevalence. Just can't go past saying something about that. Thank you. So in terms of STI screening or testing, HIV and syphilis testing are part of routine screening for all epidemiological risk groups. So if we can normalise that testing and majority of these tests will be negative, we are putting in place the normalisation of testing and making it easy for the clinician and the patients to seek that. Within that group, of course, depending on the sexual risk and practices of the patient, it determines what other tests we might be doing. And there's really fantastic guidelines for everyone out there on the Australian stiguidelines.org.au, which can break it down by population group. So you may be seeing a person who's assigned male at birth who has sex with other men, and it will talk about which sites that should be tested along with the HIV, syphilis, and hepatitis B screening tests. And then of course, there may be other risks such as people who may inject drugs or people who have been incarcerated, people who've travelled to high-prevalence countries or had risk behaviours with people from high-prevalence risk countries. So we can pop STI discussions into our pre-travel conversations with our patients and certainly on their return from travel to consider HIV and syphilis testing as part of that. There's a particular subgroup where testing is recommended approximately every 3 months, which is distinct from some of the STI testing, which we'll be doing in general practice opportunistically or when there are symptoms. Yes. So certainly there are guidelines around people's sexual practices, particularly those patients on PrEP. The current guidelines do recommend STI testing every 3 months, and that's in line with the PrEP prescription most often for people who are on daily PrEP. And a brief mention of healthcare workers. In my job, I do a lot of skin excisions and joint injections and things like that, but I don't believe that puts me at particularly high risk. It's really for where you're handling sharps in body cavities, which are not necessarily in your view at all times. That's right. And so practitioners who are conducting such examinations or procedures do need to be aware of their status, Justin. And if they are diagnosed with a bloodborne virus, then they are required to be linked to a specialist care. And in the case of HIV, have undetectable viral load and linkage with a specialist. Just to clarify, the procedures you're talking about are, for example, open abdominal or thoracic procedures, not office procedures. That's correct, yes. And there is an excellent guideline [CDNA National Guidelines for healthcare workers on managing bloodborne viruses] that we can put the link in with the Australian guidelines for practitioners. Wonderful. Thank you. Now, Louise Owen, I would like to move on now to these HIV indicator conditions. Some of these things, of course, happily we see very rarely these days such as Kaposi sarcoma, which when I was a medical student was sadly becoming common throughout the '90s, but some of them we might not think of as potential HIV indicator conditions because they're often caused by other things, but we should be testing those. So there are 3 categories of these conditions. Could you run us through those? So we're thinking about the well-known AIDS-defining illnesses as the first category. So if a patient presents with pneumonia and it's thought to be pneumocystis pneumonia, then majority of clinicians, hospitals, ICUs [intensive care units], EDs [emergency departments] would be running a HIV test for that patient. Other less well-known AIDS-defining illness include cervical cancer, Kaposi sarcoma, Hodgkin lymphoma, and also oesophageal candidiasis. But we could be possibly sure that some people in those categories are not getting a HIV test, and some may well have a reason why they have oesophageal candidiasis. But the question is, should we rule out HIV? And then there's a group which perhaps your average GP might come across a bit more often because they're not very specific for being caused by HIV, but they can be caused by it. And I think the calculation is that if the HIV prevalence is more than 0.1% or higher, then that's when we test. What are those conditions? These are conditions that do come across the daily desk of our colleagues in general practice, such as unexplained weight loss, unexplained diarrhoea, thrombocytopenia, multidermatomal shingles, or recurrent bacterial pneumonia. Any STI should prompt HIV and syphilis testing, of course, as should the diagnosis of hepatitis B or C. So many of these situations on their own may not be much of an alert, but particularly we could look at our patients and say, 'Hmm, there may have been one or 2 of these conditions in the last 12 months. We need to rule out HIV.' And in these situations, it's ideal that the clinician could ask a sexual history, but perhaps that will not be very helpful because perhaps this is a person who doesn't have any identifiable risk factors, but perhaps may be at risk from their partner or past activities. And so the clinician then says, 'You have this condition, insert thrombocytopenia or other clinical indicator condition. I suggest we need to do a number of tests and we should rule out HIV.' A lot of this is now on the HealthPathways, Justin, which can help GPs look when they're doing a thrombocytopenia screen. HIV is up there ahead of doing a bone marrow biopsy, for example. And at $15 a test, yes, it is deemed to be cost effective if the prevalence is thought to be 0.1% or more. Now, we do get asked, 'Well, how do we know what the prevalence is in our population?' And these are based mainly on European studies, but in our quest to get to zero, we do feel that it's cost effective to order the $15 test. In these situations, often we have ruled it out and the patient doesn't need multiple HIV tests, unlike the scenario where someone has an ongoing or intermittent sexual risk or other practices that puts them at risk. And the third and final category is where you really can't afford to be missing HIV. Yes. And this is often done as part of a standard workup for people who are receiving systemic chemotherapy or immune-modulating therapies. So we're just raising awareness, is that happening or are people putting a judgement on whether or not someone might be at risk of HIV and doing a test only in that scenario? So the aim is that if you're about to start systemic chemotherapy as part of the ruling out prior to that treatment, then HIV testing workup would be recommended. Let's move on to the tests themselves. As most would be aware, there is a window period for a test, which isn't perhaps so relevant for someone at continuous risk or in one of those categories we mentioned, but certainly might be relevant for someone who's had a recent episode where they may have come into contact with HIV, for example, a recent other sexually transmitted infection, and there you can get that false negative early on if you test too early. Yes. So the GP or other clinician is really just asking for HIV serology test and send that off. The lab then does one of the fourth-or fifth-generation tests, which is looking for antibody and antigen that are produced and detected in the test. So very early infection, known as the window period as you mentioned, may not be detected. And so it is good to have a history in terms of the explicit risk that the person may have had and then recommending retesting within 6 to 12 weeks after that risk. So it can be reassuring about every other, for example, sexual risk they may have had prior to this most recent one, but we've still in the window period. So Louise, until I read your article, I was unaware there was such a thing as a point-of-care rapid HIV test. Where are they recommended? Who should be using them? Well, the rapid point-of-care testing are usually used by healthcare workers and often in remote, regional areas. For example, our hepatitis C nurses who are outreach can take hepatitis C and HIV point-of-care tests with them. So the most common setting would be in outreach or rural and remote settings. And again, this is a really great extra tool that we have to exclude HIV quickly, understanding the window period that may be slightly longer than the laboratory tests, but any reactive point-of-care test would be followed with a serological test for confirmation. So like most point-of-care tests, they're a very useful screening tool where you may otherwise not get the person to have the formal test, but of course any equivocal result or positive result you'd want to back up with a formal lab test as they're not going to be quite as good. That's right. It's great. And there's also the rapid self-testing, which is available for people to apply online to get a free test delivered to the address of their choice. They are available on vending machines and other community providers. And this is another opportunity for people to self-select and have a test that they can do at home. If that test is reactive, of course it's recommended they reach out to a clinical service to have further testing and care. We'll end now on what to do with a negative result and a positive result. We've sort of covered the negative one in the sense that we take it in clinical context. Is it in the window period? Are they at ongoing risk and will need further tests? But the HIV serology is really very accurate. It's a sensitive and specific test more so than most other tests we order actually in general practice. I'm particularly interested what we do and what the lab does with a positive result. Well, the initial screening test or the ELISA [enzyme-linked immunosorbent assay] test looking for the antibodies and antigen test, if that is reactive, then that is followed on by a more sensitive and specific test, which may be the Western blot, or in some cases, an RNA test to detect the HIV virus. And again, as you mentioned, a positive test in this regard is highly sensitive and specific and conclusive of HIV infection. And in that case, the laboratory certainly automatically notifies public health, but also in the majority of cases would be contacting the clinician who ordered the test. And I guess thinking about the statistics of 0.1% and the clinical indicator condition prevalence, GPs are likely to order a lot of tests and not have a positive, but we want to reassure you that if you were to have a positive result, there will be assistance available very quickly from your local sexual health service, ID [infectious diseases] service, or other experts to assist the clinician who's made the diagnosis with linking the patient to care and getting them onto treatment really quickly. And Australia again is doing really well with that and antiretroviral medication is free to people without Medicare as well. And it's available, of course, for people with Medicare, but there may be a dispensing fee. Just a clarification there. Wonderful. Clinical Professor Louise Owen, thanks for joining us. There's lots of information in that article if anyone wants to follow up on anything we've discussed, in particular, the 3 categories of the HIV indicator conditions. Thanks for coming along today and helping clarify it all. Thanks, Justin. It's been great to chat to you today. [Music] The views of the hosts and the guests on this podcast are their own and may not represent Australian Prescriber or Therapeutic Guidelines.