Category Archives: Public Health

Glasgow Blatchford Score 2 – The case for an RCT!

Thanks for a great post, Gareth.  If you’ve landed here without reading that post, hit the link – this is a follow on, a ‘deep dive’ in the words of Smart EM – to be taken in the context of Gareth’s main post.

This is a landmark study in Emergency Medicine and gives us something useful that could reduce admissions.  With a critical appraisal hat on, however, I do think it’s important to point out a few flaws in the methodology.

Methodology of the Lancet study

The authors have essentially prospectively evaluated the performance of the GBS at several centres by reviewing case notes of patients presenting with upper GI bleed.  They then prospectively implemented the GBS, discharging patients with GBS of 0 and found that it was safe and reduced admissions.  It sounds pretty good, so why is there a problem?

The issue is that there’s no control group in the implementation phase.  When clinicians are told to use a tool that enables discharge of low risk patients, they may decide to use it in particularly low risk patients, who they’re happy to consider early discharge for.  There’s some evidence that this actually happened, as the proportion of low risk patients is greater in the implementation phase (22% vs. 16%) and the overall number of patients is enrolled is greater in the implementation phase (572 vs. 334), despite the overall recruitment period being shorter.  This is the classic problem with simple before and after analyses, and it makes the comparison of admission rates before and after implementation subject to substantial bias.

What’s more, there’s the issue of resource utilisation.  In the derivation phase, 96% of patients were admitted compared to 71% after implementation, which is great.  However, the median length of stay didn’t change (2 days in each group) although the mean length of stay reduced.  This suggests that the patients we’re avoiding admission for after implementation of the GBS would have had a short length of stay anyway (<2 days), so the reductions in length of stay are occurring in that group.  That’s still OK – so far, we’re still on to a cost saving and patients get to go home earlier.

However, you also have to consider that the low risk patients who were discharged were all given outpatient endoscopies and outpatient follow-up.  OK, only 40% actually attended for the endoscopy.  But what we don’t know is how many of them would have undergone endoscopy and out-patient follow-up with standard care – it may well have been less than 40%.  What’s more, using the score might tempt physicians to over-investigate or over-treat those who aren’t in the low risk group.

Overall impact on resource utilisation

It’s therefore possible that implementation of this protocol actually leads to a rebound overuse of resources.  To get a better idea of whether this actually happens, we need a control group.  The most obvious way to do that is to run an RCT.  Patients could be individually randomised to care guided by the GBS or standard care, or we could use cluster randomisation (e.g. randomise each centre to deliver care guided by one intervention or the other).  Alternatively, we could use a stepped wedge design, whereby we enrol a number of centres and all of them sign up to implementation of the GBS-based protocol.  Each centre is given a randomly allocated implementation date.  We then run a before and after analysis to evaluate admission rates and overall resource utilisation.  This is still a before and after analysis, but we have contemporaneous control groups at different centres.

What’s a Service Evaluation?

There’s a final point to make here.  The implementation phase was a service evaluation.  What does this mean?  Essentially, two centres implemented the protocol in practice and audited what happened.  They didn’t get consent from patients.  (They didn’t need it for this type of work).  However, it does mean that they couldn’t actually follow patients up as they would in a research study.  That means that the 60% of low risk patients who failed to show for their endoscopy went out into the ether.  They could have attended other hospitals for further care, perhaps because they were disgusted at being inappropriately discharged!  They may have undergone intervention at those centres – we just don’t know with this design.

The bottom line for clinical practice

Does this stop us from using the Glasgow Blatchford score?  No, excepting a few methodological flaws I think these authors have, on the whole, shown its safety.  I think we can use it.  Even NICE says we can use it!  We shouldn’t be so confident about the overall impact on resource utilisation though, as we just haven’t shown that in this study.

Rabies management in the ED.

Interesting article in the Journal of the Royal Army Medical Corps on the management of Rabies. Now, we don’t get a lot of Rabies in Virchester, but the weather is so terrible here lots of our patients come back having been bitten by dogs in foreign climes.There was even a death recently in the UK from Rabies contracted abroad. Apparently the patient was sent home from the ED at one point which got the media excited (though the details were somewhat more complicated).

A few key points to pick up.

1. Don’t forget to treat the wound as a bite. Obvious, but you can get so caught up in the rabies question that you forget about the basics.

2. Get advice from the HPA or local communicable diseases experts. They know more than you do!

3. Know where you can access Rabies immunoglobulin and vaccine.

As an extra thought don’t forget that European Bat Lyssavirus does occur in the UK and you should think about this in people who handle bats and occasionally in fly fisherman who may catch a bat on the wing whilst fishing.

Simon Carley

ON POST-EXPOSURE PROPHYLAXIS: a diet PEPSE served on ice

You are on a busy shift in ED when a young man in his twenties presents after having being triaged with a “personal problem” he would not disclose in triage. He has asked to see a senior doctor urgently.
When alone, he discloses unprotected oral intercourse two days ago in a local sauna for gay men. He was the recipient and there was no ejaculation involved. The details of the sexual practice itself baffle you and the patient is requesting PEPSE (post-exposure prophylaxis following sexual exposure).
You scratch your head, as the area you work in is known to have a low HIV prevalence and you are unsure if the described rather unusual sexual intercourse is in itself an indication to start PEPSE.

The British Association for Sexual Health and HIV (BASHH) in the UK have recently revised its guideline on who should receive PEPSE following sexual exposure.
The guideline is based upon a comprehensive review of the literature and the recommendations are based upon a combination of biological plausibility, cohort studies, data from PEP in other settings and expert opinion.

This is clearly a crucial decision for the patient presenting to ED at 2AM and potentially a difficult one for the EP if not aware of the guidelines or the local prevalence of HIV in his/her area of practice.

The risk of an individual acquiring HIV following an exposure is dependent upon the risk that the source is HIV- positive where unknown and the risk of infection following a specific exposure from an HIV-positive individual:
The risk of HIV transmission can therefore be calculated. Risk of transmission = risk that source is HIV-positive X risk of exposure
Knowledge of local HIV prevalence rates will clearly assist in calculating the risk of transmission and cumulative risk should be considered for repeated exposures.

It is worth mentioning that the probability of HIV transmission depends upon the exposure characteristics (anal, oral or other types of sexual practice), the infectivity of the source (viral load) and host susceptibility (immunosuppression). Some factors increase the risk of transmission like the presence of ejaculation, the presence of genital ulceration, the viral load, the absence of circumcision etc.

PEP is not 100% effective and individuals have acquired HIV despite commencing PEP following both occupational and sexual exposures. Delayed initiation of PEP, presence of resistant virus in the source, different penetration of drugs into tissue compartments, poor/non-adherence and further high- risk sexual exposures may explain some transmissions.

Adherence and completion rates to the recommended four weeks of PEP among health-care workers and individuals exposed non- occupationally have been historically poor for several reasons.

There have also been concerns that the availability of PEPSE will reduce commitment to primary prevention strategies (the use of condoms) and consequently result in more frequent high-risk behaviour.

It is essential that emergency physicians perform a risk versus benefit analysis for every individual presenting following an exposure and the decision to initiate PEP is made on a case-by-case basis.
This should consider both the risk of transmission according to exposure and the risk of the source being HIV-positive as well as the viral load in the source if known (this is clearly difficult to ascertain in most of the ED cases).

The writing committee recommends that PEPSE is indicated when the estimated transmission risk is 1 in 1000 or greater.
The same committee also feels that when the exposure is classified as ‘consider’, PEPSE should only be prescribed if there are additional factors that may increase the likelihood of transmission, i.e. following sexual assault, in the presence of an STI (i.e. where the source is known to have an STI or the exposed individual has symptoms or signs suggesting an STI) or where the source is suspected to have acute HIV infection. www.bashh.org/documents/4076

Given that, for optimal efficacy, PEPSE should be commenced as soon as possible after exposure, 24-hour access has now been made be available nationwide in the UK.

Emergency physicians therefore assume significant responsibility for provision of PEPSE, with the need for support and training from areas of local expertise.

It is recommended that individuals presenting for PEPSE should be referred and seen as early as possible by a clinician or team experienced in the management of PEPSE and with expertise in HIV testing and transmission – whether or not PEPSE is offered or accepted.

Take home message:
1. familiarise yourself with your national/local protocol for PEPSE (it is not difficult with 24h internet access)
2. know your local HIV prevalence (get yourself bleeped out of the consult room by your nurse and google it)
3. a systematic and professional approach in the often sensitive details of sexual practice is essential (who knows, you might come across something you could put into practice at home with your partner!)
4. ask for specialist help if in any doubt (pick up that phone and call a friend!)

Janos P Baombe