• An alternative model of pre-hospital care for 999 patients who require non-emergency medical assistance

      Blodgett, Joanna M; Robertson, Duncan; Ratcliffe, David; Rockwood, Kenneth (2017-05)
    • Alternatives to direct emergency department conveyance of ambulance patients: a scoping review of the evidence

      Blodgett, Joanna M; Robertson, Duncan; Pennington, Elspeth; Ratcliffe, David; Rockwood, Kenneth (2021-01)
    • Asthma: an overview of prehospital care

      Scholes, Steven (2008-12)
      Asthma exacerbations are characterized by progressive increase in shortness of breath, decrease in expiratory airflow, productive or non-productive cough, wheezing and feeling of chest tightness. Emergency hospital admissions for asthma are costly and it is estimated 75% are avoidable through effective asthma management and routine care. This article addresses asthma management in prehospital care explaining relevant underlying pathophysiology of asthma exacerbations to provide clinicians with a greater understanding of asthma and its pharmacological and ventilatory management. Abstract published with permission.
    • COPD: an overview of prehospital care

      Scholes, Steven; Hedges, Nicola (2009-12-18)
      Chronic obstructive pulmonary disease (COPD) is the name for a collection of lung diseases including chronic bronchitis, emphysema and chronic obstructive airways disease. It is a debilitating airways disease which presents to the ambulance service with varying severity and is characterized by airflow obstruction which is usually progressive, not fully reversible and does not change markedly over several months. It may coexist with other comorbidities such as cardiovascular disease, making diagnosis of exacerbations difficult. COPD management in the prehospital environment is focused on effective recognition and the early application of pharmacological intervention to alleviate symptoms using current Joint Royal Colleges Ambulance Liaison Committee Guidelines. Abstract published with permission.
    • Creating a safety net for patients in crisis: paramedic perspectives towards a GP referral scheme

      Blodgett, Joanna M; Robertson, Duncan; Ratcliffe, David; Rockwood, Kenneth (2017-01)
      Abstract published with permission. An innovative policy implemented by a UK Ambulance Service allows paramedics to refer patients to a GP Acute Visiting Service scheme. Initial evidence suggests that this alternate route of care can decrease hospital admission rates, decrease A&E waiting time and provide substantial savings for the NHS. However, there are many unrecognised barriers to referral that are not captured by the quantitative analysis. The goal of this qualitative-observational study was to gain insight into the GP referral scheme from a paramedic's perspective. All notes were transcribed, coded and analysed using a Grounded Theory approach. Four main themes emerged: 1) barriers to referral including wait time, process, and lack of confidence, experience and training 2) approaching the patient with the GP referral scheme in mind 3) frustrations with GP decision making and 4) awareness/understanding of the scheme's impacts. This study provided valuable insight into the paramedic's perspective of the GP referral scheme. Maximising understanding of the scheme, investigating the GP's perspective in decision making and ensuring knowledge and accountability of paramedics, GPs and the public were identified as solutions to strengthen and increase referral rates and scheme success.
    • End-of-life care within the paramedic context

      Wilson, Caitlin (2020-11-09)
      Edited by Tania Blackmore (2020), Palliative end of life care for paramedics provides a comprehensive overview of palliative and end-of-life care within the context of paramedic practice. This recently published book is in its first edition and is available in paperback (£29.99) or eBook (£24.99) format. It sits alongside similar publications from the College of Paramedics such as Law and ethics for paramedics and Independent prescribing for paramedics. Some of you may have noticed that these book topics reflect a selection of the paramedic e-Learning modules, which are freely available for College of Paramedic members through the e-Learning for Healthcare Hub website or via My ESR for NHS employees. The subjects covered in the ‘Paramedic – End of Life and Palliative Care’ e-Learning module loosely reflect those covered in this book; however, the book covers everything in much more detail, and includes many references to current supporting evidence, providing the reader with a greater background understanding of palliative care. The team of authors is a well-balanced mixture of academic and clinical health professionals, with three from a paramedic background and three end-of-life care specialists. The front cover of the book indicates that this book is supported by the College of Paramedics, which hints at its incredible relevance for paramedics and emergency ambulance technicians practising in the UK. Sometimes when being taught by specialists outside of the ambulance service, they impart an immense amount of specialist knowledge, yet prehospital clinicians have to decide for themselves how much is actually within their scope of practice and therefore applicable to their clinical role. Although, the editor includes a (very valid and important) disclaimer at the beginning of the book that ‘healthcare professionals should always follow local procedures and be aware of their own scope of practice’, this process of critical appraisal and judgement on applicability is made much easier by the book's close alignment with UK paramedic practice and the frequent references to the JRCALC Clinical Guidelines 2019 (Association of Ambulance Chief Executives (AACE), 2019). In fact, in that way, it is similar to the Emergency birth in the community book that I reviewed in a past issue of the Journal of Paramedic Practice (Wilson, 2019), which was supported by the AACE and JRCALC. The book takes the reader on a logical journey beginning with the broader historical, social and cultural debates about death and dying in chapter 1, followed by the various definitions of palliative care in chapter 2. Chapters 3 and 4 provide an overview of palliative care emergencies and how to recognise them, followed by guidance on symptom management. Subsequently, chapter 5 focuses on softer skills such as communication, while chapter 6 provides an overview of caring for the dying patient, delirium, medication management and discussions surrounding what may constitute a ‘good death’. Chapters 7 and 8 address the topics of ethics and professional resilience, before chapter 9 ties everything together under the title ‘the paramedic as an end of life care specialist’. A clear favourite within this book was chapter 4, which covers symptom management and seemed so applicable that it may join my ever-growing collection of ‘keep-in-helmet-bag’ books. I also really liked the many visuals, such as the image displaying the relative strength of opioids and others illustrating pain pathways and causes of vomiting and nausea. The authors have also included many educational tables, which in chapter 3 provided useful information on manifestations, relevant considerations and treatment for various palliative care emergencies such as neutropenic sepsis, superior vena cava syndrome and terminal haemorrhage. Although it will be impossible for me to remember all of these details, it will be easy to refer to these tables when thinking through differential diagnoses or reflecting on patient encounters. A great learning tool within this book are the case studies included at the end of most chapters. These cases add a practical element to the book and allow the reader to reflect upon what has been discussed in the chapter. However, many of the case studies and associated questions are complex in nature and although they are likely to have more than one right answer, there will definitely be wrong answers. I wonder if, in subsequent editions, the authors could include potential answers or discussions at the end of the book to ensure that readers are following along the right lines. I found the book to be a bit of a slow starter, as the authors use chapters 1 and 2 to introduce the reader to a wide variety of palliative care policies and frameworks in the UK. Although presented in a structured way, it is at times difficult to see how they fit together and which ones apply to paramedics. For those readers finding themselves similarly confused, I would suggest first turning to chapters 3 or 4 and then revisiting the earlier chapters to learn about the broader picture of palliative care. I think working through this book would make a useful exercise for continued professional development (CPD) as part of a paramedic portfolio or even the associate ambulance practitioner programme. In fact, the title, Palliative and end of life care for paramedics may be slightly misleading: this book is by no means solely suitable for qualified paramedics; emergency ambulance staff in other roles such as emergency medical technicians or clinical advisors within the emergency operations centre would definitely benefit from reading this book, although would have to adapt some of the advice to their own scope of practice. Overall, this book is written in simple and easy-to-understand language, provides excellent tips for further reading and cites relevant and up-to-date references throughout—what's not to love? Well, very little to be honest. I have already recommended this book to several colleagues and feel my own care of patients approaching the end of their life has improved since reading this book. I certainly feel more confident and will likely turn back to this book to answer any prehospital palliative care questions I may face in the future. The best way to summarise this book is by expressing my full agreement with the statement on the back cover: ‘it is essential reading for [prehospital clinicians] hoping to better understand the complexities of caring for patients approaching the end of life’. Abstract published with permission.
    • Exploratory study into the views of paramedics on paramedic prescribing

      Duffy, Iain; Jones, Colin (2017-07)
      Abstract published with permission. The purpose of this paper is to establish the views of a group of Paramedics on Paramedic prescribing. Although at the time of writing the proposal to the Commission on Human Medicines they rejected prescribing for Paramedics, work is still ongoing with various bodies to move forward with the application. A focus group of a small number of Paramedics was held, and the researcher performed a review of relevant literature. The development of the role of paramedic from an ambulance driver to a highly skilled and knowledgeable healthcare professional was discussed. It was established that the profession's close links with higher education institutions would be pivotal if paramedics are to be given prescribing rights. The study concluded that paramedics believe they should be able to become independent prescribers, as it would help further their career, giving the profession added credibility. As paramedics already give a rounded healthcare approach to their patients, this would only be enhanced by prescribing rights, as a ‘complete’ health care attitude could be established.
    • Heliox in acute severe asthma in the A&E setting: a review

      Scholes, Steven (2013-09-29)
      Heliox (HeO2) is a mixture of helium and oxygen, often mixed in 80:20 or 70:30 ratios for use in medicine and clinical investigations. Heliox has been available for use in the UK since 2002 and is supplied as Heliox 21 (21% oxygen and 79% helium) by BOC Gases for medical use in asthma, croup, chronic obstructive pulmonary disease and other medical procedures. Heliox use in asthma exacerbations remains largely experimental owing to the limited number of randomized controlled trials. This review aims to critically analyse the efficiency of Heliox use in acute asthma exacerbations in the Accident and Emergency (A&E) setting, evaluate its effectiveness as a medium for nebulization, and assess potential benefits to clinical practice. Prehospital application will also be discussed in moderate-severe asthma exacerbations. It is envisaged that the factors relating to Heliox use in asthma are focused to provide an additional therapy to the current choice of therapies for prehospital clinicians. Abstract published with permission.
    • How accurate is the prehospital diagnosis of hyperventilation syndrome?

      Wilson, Caitlin; Harley, Clare; Steels, Stephanie (2020-11-09)
      Background: The literature suggests that hyperventilation syndrome (HVS) should be diagnosed and treated prehospitally. Aim: To determine diagnostic accuracy of HVS by paramedics and emergency medical technicians using hospital doctors' diagnosis as the reference standard. Methods: A retrospective audit was carried out of routine data using linked prehospital and in-hospital patient records of adult patients (≥18 years) transported via emergency ambulance to two emergency departments in the UK from 1 January 2012–31 December 2013. Accuracy was measured using sensitivity, specificity, positive and negative predictive values (NPV/PPVs) and likelihood ratios (LRs) with 95% confidence intervals. Results: A total of 19 386 records were included in the analysis. Prehospital clinicians had a sensitivity of 88% (95% CI [82–92%]) and a specificity of 99% (95% CI [99–99%]) for diagnosing HVS, with PPV 0.42 (0.37, 0.47), NPV 1.00 (1.00, 1.00), LR+ 75.2 (65.3, 86.5) and LR− 0.12 (0.08, 0.18). Conclusions: Paramedics and emergency medical technicians are able to diagnose HVS prehospitally with almost perfect specificity and good sensitivity. Abstract published with permission.
    • Hyperventilation syndrome: diagnosis and reassurance

      Wilson, Caitlin (2018-09)
      Abstract published with permission. This article provides an overview of hyperventilation syndrome (HVS). Hyperventilation is to breathe in excess of metabolic requirements; in the absence of an underlying organic cause, it is defined as HVS. Alternative terms used in literature are panic or anxiety attack, panic or anxiety disorder, dysfunctional breathing and breathing pattern disorder. This article explores HVS signs and symptoms beyond the familiar clinical signposts of tachypnoea, chest tightness, paraesthesia and anxiety. It will also discuss differential diagnoses and pre-hospital treatment of HVS, focusing on reassuring patients and assisting them in establishing a good respiratory pattern. Patients with HVS use a significant amount of hospital and emergency service resources, ideally placing paramedics to diagnose and treat HVS in the pre-hospital setting to avoid unnecessary and costly hospital admissions. Further research is needed to evaluate the pre-hospital prevalence and diagnostic accuracy of HVS, identify clear diagnostic criteria and design screening tools.
    • Implementation of a prealert to improve in-hospital treatment of anticoagulant-associated strokes: analysis of a prehospital pathway change in a large UK centralised acute stroke system

      Ashton, Christopher; Sammut-Powell, Camilla; Birleson, Emily; Mayoh, Duncan; Sperrin, Matthew; Parry-Jones, Adrian (2020-05-17)
      Intracerebral haemorrhage (ICH) has the worst outcomes of all stroke subtypes, with a case fatality at 1 month of 30%–40% and only 20% regaining independence.1 Improving the implementation of existing evidence-based and guideline-recommended interventions may lead to improved outcomes.2 10%–20% of acute ICH occurs in patients taking oral anticoagulants and this is associated with a high risk of early haematoma expansion.3 4 Rapid treatment to normalise coagulation reduces this risk and may improve outcomes.4 5 The first critical step in achieving this is for suspected stroke patients on anticoagulants to undergo immediate brain imaging, allowing ICH to be identified quickly and anticoagulant reversal therapy initiated. Our regional centralised acute stroke system within Greater Manchester and Eastern Cheshire serves a population of 2.85 million and although suspected stroke patients collected by ambulance <48 hours post onset are transported to a hyperacute stroke unit (HASU), only those within 4 hours of onset are prealerted. We conducted a service evaluation to determine whether an additional prealert and emergency transport for suspected stroke on anticoagulants 4–48 hours post onset facilitated rapid imaging and hence reversal of anticoagulation after ICH on HASU arrival. A proposed prealert for anticoagulant-associated suspected strokes was agreed by the Greater Manchester Stroke Operational Delivery Network and introduced on 13 March 2018. The change in practice was disseminated by the North West Ambulance Service (NWAS) to all prehospital clinicians. https://bmjopenquality.bmj.com/content/9/2/e000883. This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/ DOI http://dx.doi.org/10.1136/bmjoq-2019-000883
    • Implementing a paediatric early warning score into pre-hospital practice

      Rolls, Martin (2019-06-01)
      Aim: This study addressed a desire by ambulance clinicians for additional education in the examination and assessment of the unwell child; it also explored whether ambulance clinicians could use a paediatric early warning score (PEWS) safely and effectively in the pre-hospital arena. Methods: A small-scale study introduced a validated PEWS into pre-hospital practice. The paediatric observations priority score (POPS) combines physiological observations with clinicians’ review. POPS uses a range of proxy measures such as work of breathing, alertness, gut feeling and known high-risk factors, to further refine the scoring. Based on a sample of over 24,000 patients, POPS has been validated for use in emergency departments (EDs). POPS can identify potentially critically unwell children as well as those fit for discharge without hospital admission, the fundamental purpose of an ED. Study participants were surveyed before and after the trial period in order to examine self-reported scores in confidence and competence levels for the child in pain, the breathless child, the child with a decreased level of consciousness, the febrile child and the seriously injured child. Completed patient report forms (PRFs) were returned to the principal investigator for further analysis. PRFs were re-distributed among participants for rescoring. Once rescoring was completed, the PRFs were returned to the principal investigator for calculation of interrater reliability. Participants remained anonymous for the survey. Results: Interrater reliability (Kappa coefficient) was calculated as 0.401, which is considered moderate agreement. As POPS rose, variance decreased. Lower POPS had variance, but these patients were lower acuity. Equal scoring in the main was reliable. Conclusion: For a cohort of ambulance clinicians, POPS was found to be safe and effective. Self-reported levels in confidence and competence improved in all patient presentations when comparing before and after the trial period (Table 1). Table 1. Comparison of mean scores for confidence and competence before and after trial period, stratified by patient presentation. Comparison of mean scores Confidence Competence Before After Diff (+/-) Before After Diff (+/-) Pain 5.01 6.34 1.33 4.17 7.49 3.32 Breathless 5.13 6.52 1.39 6.54 7.62 1.08 Decreased level of consciousness 5.93 6.47 0.54 6.04 7.58 1.54 Febrile 6.92 7.06 0.14 6.85 8.20 1.35 Seriously injured 5.95 6.44 0.49 5.99 7.60 1.61 Abstract published with permission.
    • Infections of the heart and how they relate to the ambulance service

      Savage, Leon (2015-08)
      Abstract published with permission. Background: In the pre-hospital environment, the treatment of acute coronary syndrome (ACS) is at the forefront of most clinicians’ priorities when symptoms include non-traumatic chest pain. As ACS is a leading cause of preventable deaths, less emphasis is placed on other potentially life-changing conditions that are associated with non-traumatic chest pain. Objectives: This article discusses the three main groups of cardiac infections (pericarditis, myocarditis, and endocarditis). It then discusses how they can be identified in the pre-hospital setting and how the ambulance service can contribute to the subsequent diagnosis of patients presenting with these conditions. Discussion: Pericarditis is a relatively common cause of non-traumatic chest pain. It has symptoms that can be found in the pre-hospital environment such as specific ECG changes and symptoms that can be identified during an initial consultation. Myocarditis has a low incidence rate as well as a wide variety of symptoms that can be associated with other common ailments. It is a very hard condition to determine in the pre-hospital environment. Endocarditis in the intravenous drug user population is a significant condition and has a high mortality rate.
    • Joint Royal College Ambulance Liaison Committee Airway Working Group commentary

      Jackson, Mike (2010-03)
      The publication of the paper by the Joint Royal College Ambulance Liaison Committee Airway Working Group (JRCALC AWG) will no doubt start a fierce debate among the paramedic and medical professions about prehospital intubation. Prehospital intubation performed by paramedics is a profession-defining skill, has been practised by paramedics in the UK for over 20 years, and has been a mainstay of prehospital airway management. In a survey of paramedics in the USA, prehospital intubation was ranked as a more important skill than defibrillation and patient assessment.1 Most of the literature reviewed by the JRCALC AWG was from the USA and included studies of drug-assisted intubation. Wang and associates2 examined 592 attempts at intubation in one year and found 536 of these to be successful (90.5%); another study of 264 paediatric prehospital intubations reported a much higher success rate of 99%,3 Bulger and colleagues4 in Seattle reported a success rate of 98.4% and in Bellingham, Washington, Wayne and Friedland5 reported a 95.5% success rate. It must be said that there are significant differences in the training and education of paramedics between the USA and the UK. The national standard curriculum for emergency medical technicians in the USA6 states that paramedics require only five successful intubations before graduation, whereas in the UK until recently paramedics needed to achieve 25 successful intubations. It is recognised that achieving intubation of the trachea does not necessarily mean the individual is proficient or competent in the skill of intubation. However, it must also be noted that achieving 25 intubations provides the paramedic with a higher degree of proficiency and competency than those achieving five. Limited capacity in the clinical placement circuit and the increased use of supraglottic devices for anaesthetic procedures in hospital means that paramedics are having difficulty in achieving the target of 25; as a result the accreditation bodies no longer demand that the 25 target is met, although there is still a need to learn the skill. In the future it is likely that training opportunities will be even more difficult to secure, and so the profession now finds itself at a crossroads. We need to look at what is right and what is safe for the patient, and importantly what is achievable by the profession. This will mean looking for alternative ways of achieving competence, for example, human simulation laboratories or looking at alternative airways. Recent evidence suggests that increasing the intubation experience of paramedics leads to better prehospital outcomes.7 Further evidence suggests there is no difference between experienced paramedics and doctors in performing successful intubation in prehospital cardiac arrest.8 Therefore, rather than removing the skill of intubation for all paramedics the focus should be on ensuring a proportion, for example, those in senior or advanced roles, are given the opportunity to acquire the necessary experience. If we adopt this approach the more exposure these clinicians will have the more proficient they will become, and this will result in improved outcomes. The JRCALC AWG has recognised this as a possible solution to the current problem. Ambulance services would be able to structure their response model to reflect this clinical provision and use these senior clinicians appropriately, not only to provide the expertise but also to supervise and lead on patient care at critical incidents. By using these senior clinicians the impact upon operational performance and resources will be minimised. With the training and revalidation problems we face the time is right for newly qualified paramedics and existing ones unable to maintain their intubation skills to adopt an alternative to intubation. Supraglottic airway devices are an alternative to intubation, but the suggestion by the JRCALC AWG that we should simply replace prehospital intubation by paramedics with supraglottic devices needs to be debated and researched. There is little evidence to support the effectiveness of supraglottic devices in prehospital non-fasted patients. Research to date has focussed primarily on the use of these devices in hospitals. We have no evidence to suggest that these devices are safe outside of hospitals; thus we need further research about their effectiveness. It is a gold standard in trauma that drug-assisted intubation is the best way to intubate the patient, and it is accepted that this should only be done by skilled operatives who perform the procedure regularly. However, although the JRCALC AWG agrees there is little evidence that prehospital intubation without anaesthetic drugs improves patient outcomes, there is also little evidence (especially from the UK) that prehospital intubation in patients in cardiac arrest is harmful. There are many examples in medicine in which treatment is given when it has not been proved to be effective, but the treatment continues as there is no evidence it is harmful. As there is no UK evidence that prehospital intubation by paramedics is harmful, the profession needs to continue this practice for patients in cardiac arrest—but with the skill performed by experienced senior and advanced paramedics working in a robust governance framework to ensure revalidation and maintenance of these skills. In the meantime, we need to explore the use of alternative devices including supraglottic devices, to decide if they are safe as an alternative to prehospital intubation especially for cardiac arrest, and to see if they will improve patient outcomes., https://emj.bmj.com/content/27/3/171.long. This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/ DOI http://dx.doi.org/10.1136/emj.2009.090381
    • Kerbside consultations: advice from the advanced paramedic to the frontline

      Jackson, Mike; Jones, Colin (2012-09)
      Abstract published with permission. Aim To observe the issues, benefits and challenges of providing dynamic telephone clinical advice to frontline clinicians by advanced paramedics of the North West Ambulance Service NHS Trust. Method In order to focus on the key issues the study used a mixed method approach. A group of 11 advanced paramedics took part in two focus groups which was then followed up with a questionnaire to frontline clinicians. Using focus groups in the research not only allows for the possibility of multiple realities but also for participant validation. Using a qualitative approach allowed theory to develop and emerge which was then codified into themes and the data was then used to develop a questionnaire for frontline clinicians who had received clinical advice in the past in order to provide an element of quantitative data. Findings Five themes emerged from the stud: function, responsibility, barriers, education and support. Conclusion The study finds that clarity is required in relation to responsibilities and clinicians would benefit from a structured model to communicate information over the telephone—we believe the introduction of remote advice has improved patient safety and support to staff and has created opportunity for additional learning.
    • Managing neck breathing patients in the prehospital setting: review of best practice

      Brooke, Mike; Brown, Andrea (2010-11)
      An increasing number of patients with long-term tracheostomies or laryngectomies are being managed in the community. However, recent evidence suggests that many clinicians from both the hospital and prehospital setting lack sufficient skills and knowledge to safely manage them in emergency situations. This article describes the anatomical and pathophysiological variations that may be encountered in tracheostomy and laryngectomy patients, and relates them to the adaptations that may be required when managing this group of patients in the prehospital setting. Abstract published with permission.
    • Paramedic application of ultrasound in the management of patients in the prehospital setting: a review of the literature

      Brooke, Mike; Walton, Julie; Scutt, Diane (2010-07-28)
      ABSTRACT Objectives Recently, attempts have been made to identify the utility of ultrasound in the management of patients in the prehospital setting. However, in the UK there is no directly relevant supporting evidence that prehospital ultrasound may reduce patient mortality and morbidity. The evidence available to inform this debate is almost entirely obtained from outside the UK, where emergency medical services (EMS) routinely use doctors as part of their model of service delivery. Using a structured review of the literature available, this paper examines the evidence to determine ‘Is there a place for paramedic ultrasound in the management of patients in the prehospital setting?’ Method A structured review of the literature to identify clinical trials which examined the use of ultrasound by non-physicians in the prehospital setting. Results Four resources were identified with sufficient methodological rigour to accurately inform the research question. Conclusion The theoretical concept that paramedicinitiated prehospital ultrasound may be of benefit in the management of critically ill patients is not without logical conceptual reason. Studies to date have demonstrated that with the right education and mentorship, some paramedic groups are able to obtain ultrasound images of sufficient quality to positively identify catastrophic pathologies found in critically ill patients. More research is required to demonstrate that these findings are transferable to the infrastructure of the UK EMS, and in what capacity they may be used to help facilitate optimal patient outcomes. https://emj.bmj.com/content/27/9/702.long This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/ doi: 10.1136/bmj.h535