Guest blog post by Dr Stuart Winearls, ACCS trainee

This Educational post is divided into three sections:

1. A background refresher on HIV infection
2. Post Exposure Prophylaxis – follow a virtual case
3. Testing for HIV in the Emergency department: when and how should we do it?

1) A little back ground refresher

• HIV is a retrovirus that infects CD4 +ve T cells
• Prevalence rates vary widely according to population group and geography. People from Sub Saharan Africa, intravenous drug users (IVDU)and men who have sex with men (MSM) are all higher risk groups.
• After initial infection with a spike in viral load a variable latent period ensues lasting from years to decades.
• Eventually as the CD4 count falls opportunistic infections develop leading to the syndrome of AIDS – Acquired Immunodeficiency Syndrome
• Treatment with a combination of drugs which block viral RNA conversion and viral protein cleaving known as HAART- highly active anti-retroviral treatment has dramatically improved survival.

Three Clinical Phases

10 Infection	Latent Phase	Symptomatic HIV & AIDS
Spike in viral load = Most infectious period Often associated with a seroconversion illness Can we identify these patients?	Variable length – years to decades with low vial loads, a falling CD4 count and no symptoms Should we screen? More later with the CEM guidance.	As CD4 count falls patients become more immunodeficient & thus susceptible to infections Progressing to opportunistic infections and death

2) Post Exposure Prophylaxis

The most likely way that we in the emergency department will encounter HIV is in the context of post exposure prophylaxis PEP. To illustrate some of the challenges and the key pieces of information we will need to gather to manage these cases let’s look at an example.

PC: Personal Problem

A tearful 51 year old man with a PMH of an NSTEMI 3yrs ago attends having just had an unprotected ‘fling with a black guy’, he is worried that he will get HIV and asks if there is anything he can do to stop himself getting HIV.

”What

SelectShow Answer

Timing of exposure – PEP is less efficacious if taken later and isn’t advised if exposure was greater than 72hrs ago. What does he mean by ‘fling’? – Different exposures carry differing risks and we need to be very clear on the nature of the exposure to counsel him on the risk. See the table below. What does he mean by ‘black guy’? – Different patient population groups have different disease prevalence rates. See the table below for some of the higher risk groups. This question is trying to establish the concept that: Transmission risk = Risk of exposure multiplied by risk the source is HIV positive

”What	SelectShow Answer
The answer is provided in table 3 below This question is trying to get you to think about two key points. Firstly how dramatically the risk calculation is affected by knowing the HIV status of those involved and that particular groups in certain areas (not just London) are at much higher risks.

Would you advise him to take Post Exposure Prophylaxis?

SelectShow Answer

This question is about risk vs benefit ratio. There is limited evidence on the efficacy of PEP. This comes mainly from animal studies (BASHH guideline 2011) The drugs used come with side effects ranging from hypersensitivity reactions, nausea, diarrhoea and hepatotoxicity although more modern combinations have minimal side effects. There are also several important drug interactions to be aware of. In this case the patient has had an NSTEMI and is probably on a statin (this is a tricky part of the question) which is a drug group interacting with Protease Inhibitors. You can review interactions via http://www.hiv-druginteractions.org/ Given these complexities the decision to initiate PEP should be made in conjunction with a specialist who is experienced in assessing the transmission risk, selecting an appropriate regime and is able to provide adequate follow up for the patient. For your information and to help you make a better referral bellow is a table from the BASHH guideline.

3) Testing for HIV in the Emergency department?

Should we ever consider performing and HIV test in A&E? This question is covered by College of Emergency Medicine (CEM) guidance. It is easier to understand when it is broken down into 3 sections:

Performing the test

Ok so we have decided that in this situation testing a given patient for HIV is important. How do we go about it? As with most things some clever people have put some guidance together for this. See UK national guidelines on HIV testing 2008.

Here are three questions you might be considering along with responses from the guidelines:

What to do with the result which is your responsibility to follow up?

Bringing it all home

• In the Emergency Department we have patients who may be seroconverting, latent or symptomatic with HIV. We have an opportunity to recognise, diagnose and treat these patients.
• Although in many parts of the UK the background risk is below the 2/1000 threshold for population screening it is important to weight up the risks and benefits when considering the use of PEP. Think of risk from exposure multiplied from risk that donor has HIV and use those BASHH tables. Earlier PEP is better.
• Considering HIV testing early in the course of a patients presentation – don’t leave it to the medics. You should be able to gain consent as lengthy pre test counselling should not be required. By diagnosing HIV early it can be treated effectively. Think about HIV in patients presenting with a serious infection, especially when there are risk factors.
• What is your departmental policy on following up HIV tests ordered in the department on patients you send home?

References:

• UK guideline for the use of post-exposure prophylaxis for HIV following sexual exposure (2011). 
• College of Emergency Medicine (UK) Best Practice Position Statement (October 2012)
• UK national guidance on HIV testing 2008