Large variation in laboratory tests for chest pain in emergency departments

12th September 2021

Laboratory tests requested by emergency care clinicians are often outside of guidelines and driven by both local and systemic factors.

Within an emergency care setting, the use of diagnostic tests helps with the detection or exclusion of a disease. Although diagnostic tests only account for a small proportion of a hospital’s budget, between 60 and 70% of all clinical decision-making is estimated to be based on the results of a diagnostic test. Despite this, in a review of studies, it was found that 45% of laboratory tests in healthcare are under-utilised compared to 21% which are over-utilised. In an effort to ensure both consistent and rational use of diagnostic and laboratory tests, the Sensible Test ordering Practice initiative was developed in Australia. However, in an analysis of tests ordered following the introduction of the initiative, it was found that just over a third (34.4%) of laboratory tests requested were unnecessary, i.e., generally not indicated. In trying to gain a better understanding of why such tests were being ordered, a team from the Australian Institute of Health Innovation, Sydney, Australia, undertook a qualitative study with clinicians. The team conducted semi-structured interviews and based on the themes identified developed targeted questions to be used with focus groups and focused on patients who presented with undifferentiated chest pain at an emergency department (ED).

Findings
While clinical staff were fully aware of the need to rationalise requests for laboratory tests, the adherence to sensible test ordering was affected by several local and systemic factors. For example, clinicians would order tests that were beyond the patient’s ED encounter often because of requests from other departmental specialists, e.g., can you also order this or that test. Furthermore, laboratory tests would be ordered in anticipation of the those required by the team admitting a patient, even though such tests were somewhat irrelevant within the ED setting. In other words, clinicians ordered tests beyond their remit to facilitate the entire patient’s hospital journey.

Another factor identified was the existence of conflicting guidelines. Although advice on the required tests were contained with the decision-support, electronic medical record (eMR), clinicians noted for example, that the clinical pathway on the eMR required additional tests to those in the order set for ischaemic chest pain, leading to an inconsistency. Moreover, with limited in-house speciality and diagnostic services in some hospitals, clinicians pre-emptively ordered tests for which they knew there would be a longer turnaround time after hours. Additional and unnecessary tests were also requested when patients were transferred to another centre, simply because clinicians were aware of the need for these tests to ensure acceptance at the receiving centre. Finally, while greater use of technology enabled laboratory testing requests much easier, the existence of multiple order screening within the eMR made it difficult to establish a common ordering process.

Summarising their findings, the authors noted that the variability in ordering of laboratory tests was influenced by requirements for admission, conflicting guidelines, availability of in-house resources and the features of of the eMR system. Given that the ED is perceived as the ‘front door’ it was not uncommon to see the ordering of laboratory tests which were beyond the scope of the ED but pertinent for other or later aspects of patient care. The authors concluded that beyond standardisation of laboratory and clinical decision-support systems, attempts to address the variation in laboratory tests need to address both local and systemic factors.

Citation
Li J et al. Why is there variation in test ordering practices for patients presenting to the emergency department with undifferentiated chest pain? A qualitative study. Emerg Med J 2021.

Combined thin film and rapid diagnostic test an effective malaria screen

11th August 2021

A malaria screen based on the use of a thin film and a rapid diagnostic test has been shown to be an effective within emergency departments.

Malaria is caused by the Plasmodium falciparum parasite and is spread to humans after being bitten by an infected female Anopheles mosquito. Malaria is extremely common and according to data from the World Health Organisation, in 2019, there were an estimated 229 million cases of malaria across the world and approximately 409,000 deaths. Symptoms of malaria include non-specific flu-like illness with fever, sweats and chills. Although malaria is endemic in sub-Saharan Africa and South East Asia, the disease still occurs in those who have returned from travelling to malaria areas. For example, in 2018, there were 1683 cases of imported malaria in the UK and this figure has remained remarkably constant over the past 10 years. An important first step in the management of travellers is a malaria screen to identify those with the condition. According to UK guidelines published in 2016, the best diagnostic procedure is examination of thick and thin blood films by an expert to detect the presence of the malarial parasite. Moreover, the guidelines also recognise that malaria can also be accurately diagnosed using rapid diagnostic tests (RDTs). In fact, a Cochrane review concluded that RDTs have a high sensitivity such that these can replace or extent the access of diagnostic services for uncomplicated plasmodium falciparum (P. falciparum) malaria. Guidance from the Haematology Task Force, has recommended that if the initial malaria screen is negative despite a strong clinical suspicion of infection, the films should be repeated after 12 to 24 hours and again after 24 hours. Nevertheless, this requires the patient to return to a hospital for repeat testing and it cannot be guaranteed that someone likely to be infected will return to a hospital. Thus, in order to optimise the malaria screen process to ensure that patients are successfully identified and using a combination of thin film and RDTs, a team from the Emergency Department, Manchester University, Manchester, UK, undertook a retrospective analysis of the value of this single malaria screen consisting of a RDT and a thin film over a 5-year period.

Findings
The study included a complete malaria screen, i.e., thin film and RDT, for 1331 unique patients with an average age of 30.6 years (51.3% male). A total of 104 positive tests were identified from the screening of which 103 were for single malarial species (74 P. falciparum, 23 P. vivax, 6 P. ovale and one mixed infection). This gave a background malaria prevalence of 5.6% for P. falciparum and 7.8% for any species. Using this approach, the authors calculated the sensitivity for the detection of P. falciparum as 100% and the specificity was 99.4%. For the detection of any malaria species, the sensitivity was 99% and the specificity 99.5%.

The authors concluded that a single malaria screen using a combination of a thin film and a RDT is likely to be sufficient to identify P. falciparum in the returning traveller, avoiding the need for a return visit when the initial film is negative. They also called for further work to confirm the value of this approach.

Citation
Reynard C et al. A diagnostic evaluation of single screen testing for malaria in the returning traveller: A large retrospective cohort study. Acad Emerg Med 2021

Updated irritable bowel syndrome guidance suggests probiotics as a treatment

6th July 2021

Updated UK guidance indicates that probiotics could be effective for global symptoms and abdominal pain in irritable bowel syndrome.

The British Society of Gastroenterology (BSG) has revised its 2007 guidelines on the management of irritable bowel syndrome (IBS). The latest guidance covers all aspects of the condition ranging from initial assessment and management through to secondary care referral and any subsequent investigations that should be undertaken within that setting. The guideline makes reference to the revised diagnostic Rome IV criteria produced in 2016 and notes that while the criteria are an improvement on the earlier Rome III, the revision is perhaps more restrictive and calls into question whether these latest changes can be used to diagnose irritable bowel syndrome. The BSG therefore suggests that a more pragmatic definition of the condition is provided by NICE which states that the diagnosis should be considered only if the person has abdominal pain or discomfort that is either relieved by defecation or associated with altered bowel frequency or stool form. Furthermore, the BSG guidance recommends that all patients with IBS symptoms should have a full blood count, C-reactive protein or erythrocyte sedimentation rate, coeliac serology and that clinicians should discuss the underlying diagnosis, its causes and natural history to the patients. The guidance, while accepting a limited evidence-base, advises that all patients should take regular exercise and that soluble fibre is an effective treatment for global symptoms and abdominal pain. In contrast, it recommends against the use of insoluble fibre (e.g., wheat bran) as this might exacerbate symptoms.

Medical treatments endorsed for irritable bowel syndrome include loperamide, especially where IBS is associated with diarrhoea, antispasmodics and peppermint oil and polyethylene glycol for associated constipation. Where there is uncertainty over the diagnosis or if symptoms are refractory, a referral should be made to secondary care. Several second-line therapies including tricyclic antidepressants, selective serotonin re-uptake inhibitors, linaclotide, lubiprostone and plecanatide. There is also a discussion of new and emerging treatments together with a recognition of the value of cognitive behavioural therapy, gut-directed hypnotherapy and general psychological therapies.

Probiotics
One area new to the guideline is the acknowledgement of a potential pathological role of an altered microbiome and which has led to interest in the use of probiotics as a potential treatment for IBS. For the guideline, the authors updated a 2018 meta-analysis on the efficacy of probiotics and found that compared to placebo, a combination of probiotics, had a significant effect on global symptoms or abdominal pain (relative risk, RR = 0.79, 95% CI 0.70–0.89). This effect was also significant for individual species including lactobacillus, Bifidobacterium and Escherichia. Based on these data, the guidance recommended that patients wishing to use probiotics should take them for up to 3 months to assess the potential benefit.
The guideline concludes that irritable bowel syndrome is a multifactorial disorder that requires a positive diagnosis and the implementation of both non- and pharmacological therapy to improve symptoms and quality of life.

Citation
Vasant DH et al. British Society of Gastroenterology guidelines on the management of irritable bowel syndrome. BMJ 2021