Core Topics in General & Emergency Surgery: Companion to Specialist Surgical Practice (3 page)

Kathryn A. Rigby and
Jonathan A. Michaels

The concept of evidence-based medicine (EBM) was introduced in the 19th century but has only flourished in the last few decades. Historically, its application to surgical practice can be traced back to the likes of John Hunter and the American Ernest Amory Codman, who both recognised the need for research into surgical outcomes in an attempt to improve patient care.

In mid-19th century Paris, Pierre-Charles-Alexander Louis used statistics to measure the effectiveness of bloodletting, the results of which helped put an end to the practice of leeching. Ernest A. Codman began work as a surgeon in 1895 in Massachusetts. His main area of interest was the shoulder and he became a leading expert in this topic as well as being instrumental in the founding of the American College of Surgeons. He developed his ‘End Result Idea’, a notion that all hospitals should follow up every patient it treats ‘long enough to determine whether or not its treatment is successful and if not, why not?’ in order to prevent similar failures in the future.
²
Codman also developed the first registry of bone sarcomas.

In the UK, one of the most important advocates of EBM was Archie Cochrane. His experiences in the prisoner of war camps, where he conducted trials in the use of yeast supplements to treat nutritional oedema, influenced his belief in reliable and scientifically proven medical treatment. In 1972 he published his book
Effectiveness and Efficiency
. Cochrane advocated the use of the randomised controlled trial (RCT) as the gold standard in the research of all medical treatment and, where possible, systematic reviews of these trials. One of the first systematic reviews of RCTs was of the use of corticosteroid therapy to improve lung function in threatened premature birth. Although RCTs had been conducted in this area, the message of the results was not clear from the individual studies, until the review overwhelmingly showed that corticosteroids reduced both neonatal morbidity and mortality. Had a systematic review been conducted earlier, then the lives of many babies could have been saved, as the review clearly showed that this inexpensive treatment reduced the chance of these babies dying from complications of immaturity by 30–50%.
³
In 1992, as part of the UK National Health Service (NHS) Research and Development (R&D) Programme, the Cochrane Collaboration was founded.

Subsequently, in 1995, the first centre for EBM in the UK was established at the Nuffield Department of Clinical Medicine, University of Oxford. The driving force behind this was the American David Sackett, who had moved to a new Chair in Clinical Epidemiology in 1994 from McMaster University in Canada, where he had pioneered self-directed teaching for medical students.

From these roots, interest in EBM has exploded. The Cochrane Collaboration is rapidly expanding, with review groups in many fields of medicine and surgery. EBM is not limited only to hospital-based medicine but is increasingly seen in nursing, general practice and dentistry, and there are many new evidence-based journals appearing.

While clinical experience is invaluable, the rapidly changing world of medicine means that clinicians must keep abreast of new advances and, where appropriate, integrate research findings into everyday clinical practice. Neither research nor clinical experience alone is enough to ensure high-quality patient care; the two must complement each other. Sackett et al. identified five steps that should become part of day-to-day practice and in which a competent practitioner should be proficient:
⁴

This chapter discusses the steps that are necessary to identify, critically appraise and combine evidence, to incorporate the findings into clinical guidance, and to implement and audit any necessary changes in order to move towards EBM in surgery. Many of the organisations and information sources that are relevant to EBM are specific to a particular setting. Therefore, the emphasis in this chapter is on the health services within the UK, although there are comparable arrangements and bodies in many other countries. Links to a number of these are given in the Internet resources described at the end of the chapter.

In 1991, there was still a widely held belief that only a small proportion of medical interventions were supported by solid scientific evidence.
⁵
Jonathan Ellis and colleagues, on behalf of the Nuffield Department of Clinical Medicine, conducted a review of treatments given to 109 patients on a medical ward.
⁶
The treatments were then examined to assess the degree of evidence supporting their use. The authors concluded that 82% of these treatments were in fact evidence based. However, they did suggest that similar studies should be conducted in other specialities. The importance of evidence-based health care in the NHS was formally acknowledged in two government papers,
The new NHS
⁷
and
A first class service
.
⁸
These led to the development of the National Service Frameworks and the National Institute of Clinical Excellence (NICE).

In surgery there is a limited body of evidence from high-quality RCTs. For an RCT to be ethical there needs to be a clinical equipoise. That is, there needs to be a sufficient level of uncertainty about an intervention before a trial can be considered. For example, it would be unethical to conduct an RCT in the use of burr holes for extradural haematomas, because the observational data alone are so overwhelming as to the high degree of effectiveness that it would be unethical to deny someone a burr hole to prove the point.

Many surgeons feel unhappy with having to explain to a patient that there is clinical uncertainty about a treatment, as patients have historically put their trust in surgeons' hands. This reluctance to perform RCTs and the belief that they would be difficult to carry out has led to practices that are poorly supported by high-quality evidence. For example, there is widespread use of radical prostatectomy to treat localised prostatic carcinoma in the USA, despite a distinct lack of evidence to support this procedure.
⁹

New technologies in surgery may be driven into widespread use by market forces, patients' expectations and clinicians' desire to improve treatment options. For example, with laparoscopic surgery, many assumed that it must be ‘better’ because it made smaller holes, there was less pain involved and therefore patients left hospital sooner. It was only after many hospitals had instituted its use that concerns were raised about its real benefits and the adequacy of training in the new technology. In 1996, a group of surgeons from Sheffield published a randomised, prospective, single-blind study that compared small-incision open cholecystectomy with laparoscopic cholecystectomy.
¹⁰
They demonstrated that in their hands the laparosopic technique offered no real benefit over a mini-cholecystectomy in terms of the postoperative recovery period, hospital stay and time off work, but it took longer to perform and was more expensive.
¹⁰
There were, however, other factors that may have influenced the results from this study, including surgeon experience, and mini-cholecystectomy has not been widely adopted.

The MRC Laparoscopic Groin and Hernia Trial Group undertook a large multicentre randomised comparison between laparoscopic and open repair of groin hernias.
¹¹
The results demonstrated that the laparoscopic procedure was associated with an earlier return to activities and less groin pain 1 year after surgery but it was also associated with more serious surgical complications, an increased recurrence rate and a higher cost to the health service. They suggested that laparoscopic hernia surgery should be confined to specialist surgical centres. NICE have since published guidelines which recommend that laparoscopic surgery is now one of the treatment options for the repair of inguinal hernias.

Some would argue that surgery, unlike drug trials, is operator dependent and that operating experience and skill can affect the outcome of an RCT, and cite this as a reason for not undertaking surgical trials. Although operator factors can introduce bias into a trial, the North American Symptomatic Carotid Endarterectomy Trial has shown that such problems can largely be overcome through appropriate trial design.
¹²
Only surgeons who had been fully trained in the procedure, and who already had a proven low complication rate, were accepted as participants in the trial.

These examples illustrate a clear need for high-quality research to be undertaken into any new technology to assess both its efficacy and its cost-effectiveness before it is introduced into the healthcare system.

However, concerns have been raised about EBM. Sceptics have suggested that it may undermine clinical experience and instinct and replace it with ‘cookbook medicine’ or that it may ignore the elements of basic medical training such as history-taking, physical examination, laboratory investigations and a sound grounding in pathophysiology. Another fear is that purchasers and managers will use it as a means to cut costs and manage budgets.

Nevertheless, EBM can formalise our everyday procedures and highlight problems. It can provide answers by ensuring that the best use is made of existing evidence or it can identify areas in which new research is needed. Although it has a role in assessing the cost-effectiveness of an intervention, it is not a substitute for rationing and often results in practice that, despite being more cost-effective, has greater overall cost.
¹³

EBM requires a structured approach to ensure that clinical interventions are based upon best available evidence. The first stage is always to pose a clinically relevant question for which an answer is required. Such a question should be clear, specific, important and answerable. One way of formulating questions is to think of them as having four key elements (PICO):

Therefore, the question ‘What is the best treatment for cholecystitis?’ needs to be much more clearly formulated if an adequate, evidence-based approach is to be used. A much better question would be ‘For adult patients admitted to hospital with acute cholecystitis (the
population
), does early open cholecystectomy, laparoscopic cholecystectomy (the
interventions
) or best medical management (the
comparison
) produce the lowest mortality, morbidity and total length of stay in hospital (the
outcomes
)?’ Even this may require more refinement to define further the exact interventions and outcomes of interest.

Once such a question has been clearly defined, a number of further stages of the process can follow: