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CHAPTER 2 introduction to evidence-based practice in evidence-based pharmacy 2nd edition
  1. Phil Wiffen1,
  2. Tommy Eriksson2,
  3. Hao Lu3
  1. 1Pain Research Unit, Churchill Hospital, Oxford, UK
  2. 2Department of Clinical Pharmacology, Laboratory Medicine, Lund University, Lund, Sweden
  3. 3Beijing United Family Hospital, Beijing, China
  1. Correspondence to Professor Phil Wiffen, Pain Research Unit, Churchill Hospital, Old Road, Oxford OX3 7LE, UK; phil.wiffen{at}

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About this chapter

This is an introduction to evidence-based practice for pharmacist. The following chapters will provide academic and practical information including tools, sources and resources for how to best practice evidence-based pharmacy. In this chapter we give some basic information and some examples of problems and limitations from studies and practices.

What do we mean by “evidence-based clinical practice?”

Evidence-based clinical practice describes the complex process of decision making and places it in the context of basing decisions on a systematic appraisal of the best evidence available.

It requires a number of skills and an ability to:

  • define criteria, such as effectiveness, safety and acceptability

  • find the evidence

  • assess the quality of the evidence

  • assess whether the results of the research are generalisable or applicable to the whole population from which the subjects have been drawn

  • assess whether the results of the research are applicable to the local or patient specific situation.

The challenge for evidence-based pharmacy is twofold. First to develop evidence-based medicine skills for use in clinical pharmacy whether in the secondary care setting on the ward or in primary care dealing with patients who present with problems or issues surrounding prescribed medicines.

The second challenge is to find the evidence to support existing practice and to inform practice developments.

Evidence-based medicine

Much has been written on this subject but two definitions are useful. The first from Professor David Sackett:1

Evidence-based medicine is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients

Sackett et al1

The authors go on to state that the practice of Evidence Based Medicine requires the integration of individual clinical expertise with the best available external clinical evidence from systematic research.

The second definition is from a team at McMaster University in Canada:

Evidence based medicine is an approach to health care that promotes the collection, interpretation and integration of valid, important and applicable patient reported, clinician observed and research derived evidence. The best available evidence, moderated by patient circumstances and preferences, is applied to improve the quality of clinical judgements.

McKibbon et al2

The Sackett definition deals with the criticism that EBM is somehow a cookbook approach, as some of its critics have argued. Clinical expertise is required by clinician and pharmacist alike; the challenge is to integrate that expertise with the best evidence available. The McKibbon definition starts from the basis of collating the evidence and then applying the evidence in the clinical setting moderated by patient circumstances and preferences. One example concerns non-steroidal anti-inflammatory drugs. There is good evidence (illustrated later) to show that non-steroidal anti-inflammatory drugs are potent analgesics in the acute pain setting, certainly better than paracetamol, dihydrocodeine or codeine, yet they are not without risk. It would be unwise to use this class of drugs in a patient who is drifting into acute renal failure or reported a history of gastric ulceration. The medicine which can provide the best outcome has to be considered in the context of the individual patient.

All this raises the question of what constitutes evidence. There have been a number of approaches to define levels of evidence. One of the earliest was presented in cancer pain guidelines developed by the US Agency for Health Care Policy and Research3 in 1994, and adapted by an EBM journal called Bandolier. (see box 1). Over recent years, a whole industry seems to have developed being led by prominent systematic reviewers. This is known as the GRADE working group. The website has a huge amount of information (

Box 1

Levels of evidence6

Type and strength of efficacy evidence

  • Strong evidence from at least one systematic review of multiple well-designed randomised controlled trials.

  • Strong evidence from at least one properly designed randomised controlled trial of appropriate size.

  • Evidence from well-designed trials without randomisation, single group prepost, cohort, time series or matched case-controlled studies.

  • Evidence from well-designed non-experimental studies from more than one centre or research group.

  • Opinions of respected authorities, based on clinical evidence, descriptive studies or reports of expert committees.

Evidence-based pharmacy practice

While systematic reviews are starting to appear about pharmacist interventions,4 good evidence is hard to find when classified according to box 1. Pharmacists have certainly written much Type V evidence, but types 1 or 2 are harder to find.

For example, Pharmaceutical Care defined by Hepler and Strand5 as ‘The responsible provision of drug therapy for the purpose of achieving definite outcomes that improve a patients quality of life’ has gained wide acceptance and is often discussed, yet the concept of Pharmaceutical Care has been poorly researched. There are now over 5000 articles on this subject, but the majority offer little more than opinions or accounts of activities involving small numbers of practitioners or patients. The demand for evidence to support activity and development could cause problems for the pharmacy profession unless there is a realignment to ensure that the research that is currently taking place is strengthened to produce evidence that is of a higher quality. On the other hand there is good systematic review evidence for the value of clinical pharmacy services in terms of saving lives, improving patient outcomes and reducing costs.4

The well-informed patient

Patients are becoming increasingly knowledgeable about their own conditions, and the treatment options available for their disease encompassing conventional and unconventional medicine. A great deal of information has always been available for patients. Many start with patient support groups that exist particularly for the more serious, long-term or life-threatening illnesses. Recent times have seen an explosion of information through the internet. The power of search engines means that information is readily available, not to mention blogs or discussion groups for almost every conceivable question.

The internet is generally non-judgmental, patients can ask the most trivial of questions and someone will be happy to answer. Unfortunately, the information usually comes without a quality rating, so requires some careful interpretation. Pharmacists who want to practice evidence-based pharmacy will be better placed to serve their clients by being aware of the potential of high-quality internet sites that can be recommended to patients. In this book, several chapters focus on tools, sources and resources for how to best practice evidence-based pharmacy.

In spite of all this, the patient is generally in the hands of the professional who often does not provide information for fear of appearing ignorant or because of busyness.

The scenario of the pharmacist simply handing over a bag of dispensed items is still far more common than we may be prepared to admit. If we do not respond to the need to be providers of quality information, then others will do it for us. An example would be when the patient is starting on diclofenac for long-term arthritis pain control from the pharmacy. The patient may have read a BBC news article titled ‘Painkiller drug diclofenac “overused” despite heart risk’, and then become concerned about whether it's still safe to use. If the pharmacist does not open the line of conversation to discuss with the patient about the need for, and the side effects of, the medication, the patient may stop using the drug due to the concerns about the adverse effects.

The limitations of evidence-based healthcare

An evidence-based approach provides some means for those providing healthcare to determine the best mix of services within limited resources. There is no guarantee, however, that benefits identified in the research setting can always be realised in practice without quality management.

Managers have the responsibility to ensure that healthcare under their supervision is supported by high-quality evidence, and that it does more good than harm. They should ensure that the overall mix of services is that which provides the greatest benefit for the population being served. These services should be of sufficiently high standard to ensure that the benefits demonstrated in research studies are in fact realised, as well as providing value for money.

The best healthcare is characterised by:

  • no ineffective or harmful interventions

  • most effective interventions available for those groups of patients most likely to benefit

  • services delivered at the highest possible quality (box 2).

The health of a given population is determined by more than healthcare, the other factors include the physical environment, social environment, lifestyle and genetics (box 3).

Box 2

Best healthcare7

  • No ineffective or harmful interventions.

  • Most effective interventions available for those groups of patients most likely to benefit.

  • Services delivered at the highest possible quality.

Box 3

Factors that determine health

  • Social environment and lifestyle

  • Physical environment

  • Healthcare

  • Genetic makeup

Governments have been slow to incorporate such concepts into their thinking, and so we continue to see departments, such as transport and social services, having no interaction with health even though there is good evidence to show they are all important in maintaining and improving the health of a nation.

Implications for the patient and professional consultation

The scenario of the patient arriving at a consultation armed with a package of information downloaded from the internet is now common. The professional and the patient bring a set of unspoken values to the decision-making process which needs to be considered. Professionals are often seeking to answer the questions which they think is in the mind of their patient, but equally often fail to ask the patient what is really bothering them. For example, a young female transplant patient may be more concerned about the growth of facial hair than to know how to take her cyclosporine at the correct time, she may in fact decide not to take the cyclosporine at all if the side effects cause embarrassment.

The setting for the discussion is a particular challenge for the pharmacist. The clinical pharmacist on a ward often finds patients willing to discuss their medication problems. The situation may be different when the scene changes to the outpatient pharmacy where a patient may have waited a long time to see the doctor, followed by a lengthy wait for the prescription to be dispensed. In this case, patients may not be interested in the information that needs to be conveyed. There are three elements to this communication:

  • information is given to the patient

  • the information undergoes interpretation by the patient

  • discussion between the pharmacist and the patient.

Sadly, the process often gets no further than the first one, and the patient then tries to remember what the important point was, and has missed the valuable information that should have been understood.

Providing evidence-based information

Information, and also the way of presenting the information to patients, must be evidence based and adapted to the situation and the patients’ needs and preferences. Pharmacists cannot provide a quality service if they do not have access to patient notes. The temptation, particularly in the outpatient setting and in community pharmacy, is to assume a diagnosis based on the prescription. In the ward setting, the pharmacist should have access to the patient notes which may contain information, such as a serious diagnosis, which the patient has not requested and does not wish to know, obviously these situations require careful handling.

The pharmacist has a duty of care to ensure that information provided to patients is backed up by reliable sources and evidence. This applies equally to the patient who requires a ‘stronger’ analgesic for a minor injury, or for advice for complex and potentially toxic treatment regimes. There may also be a need to reinforce information provided by other professionals involved in the care of the patient.

Pharmacists need to present information in a way that patients that can understand and accept. For example, if the pharmacists inform the patient that Azathioprine can cause blood disorders or bone marrow suppression, the patient can be very concerned about the adverse effect of the drug; whereas, if the patient is told to report fever symptoms, then the patient is more likely to accept and remember.

Patients will often get their information from a number of sources including the media. New drugs are often featured on news bulletins, and medical advice is freely offered in the newspaper supplements and magazines. New arrivals on the inpatient ward may get advice from their fellow patients on the relative merits of the analgesics, hypnotics or aperients available. In these situations, it is really important to have the evidence available. Clinical ignorance is perhaps acceptable when there is no knowledge to be known, but not so if the knowledge is available but unknown to the practitioner.

Reasons for getting things wrong. There may be:

  • no knowledge to know

  • knowledge not known to the practitioner

  • knowledge known, but it cannot be easily applied to the clinical situation being addressed

  • knowledge known but it is wrong.


Once a patient has been given the information, it has to be interpreted and may require time for consideration. The provision of written information may be important in the form of a label and as additional information. Such information should be readable and of the correct length. Many of the industry patient information leaflets are poor examples of how to do this. Labelling of medicines is often in a form of words which are not readily understood by a significant proportion of the population. Some of the stock phrases require some explanation such as ‘Warning. Do not drink alcohol’ or ‘ Warning. This medicine may make you sleepy, if this happens do not drive or use tools or machines’.


The relationship established between the patient and the practitioner will determine the quality of the discussion. An explanation of the medicines and some further relevant information often provides the platform for this to take place.

Practicing evidence-based clinical pharmacy

Building on the definition of evidence-based medicine quoted at the beginning of this chapter, it is possible to define evidence-based clinical pharmacy as the conscientious, explicit and judicious use of current best evidence when making decisions about individual patients. The use of the word ‘judicious’ signifies that the pharmacist must take into account the patient’s condition, values and circumstances.

Evidence and the pharmaceutical industry

The pharmaceutical industry, in general, has been slow to pick up on the evidence-based medicine movement although attitudes are now changing and a number of companies are getting involved. The approaches outlined above need to infiltrate the whole of the management of medicines, and there is much for the industry to note.

Sadly, many clinicians and pharmacists around the world gain their knowledge from the ‘drug representatives’. The industry sees the representative or drug detailer as an important part of their sales strategy. Many companies regulate the behaviour of their representatives by setting sales targets and providing incentives. These are now heavily regulated in Europe and other countries. However, it is not surprising that some reps use a variety of measures to achieve those results, and companies have little control over what happens in the field. An extreme example led to a notable quotation from a drug representative working in Mumbai8 who stated that he worked on the principle of three ‘Cs’ for persuading clinicians to prescribe. ‘My strategy is to first try to convince the doctor to support the product. If that doesn't work, I try to confuse the doctor by filling him with unnecessary technical details. If nothing else, this at least generates some curiosity in the product. If I don't succeed in this too, then I try to corrupt him. A generous quota of samples, expensive gifts, invitation to cocktail parties and what not from the company often does the job.’

Mumbai Pharma Rep Three ‘Cs’ policy:

  • convince

  • confuse

  • corrupt.

Of course, we may argue that the developed world has left these tactics behind and all is controlled by codes of practice. There have been some studies around these issues, and one interesting piece of work carried out as a Masters thesis in Australia9 would suggest all is not as sound as we might like to think. There is clear indication that while representatives provided information on indications, dosage and administration, minimal information was provided in other areas, particularly those associated with product risk. Presentations were often not judged to be balanced and were found to contain inaccuracies. The study was carried out in Melbourne and a sample of medical practitioners was asked to audio-tape their encounters with pharmaceutical representatives as well as complete a one-page questionnaire for each interview. The study had ethical approval and the GP involved and the representative were required to complete a consent form. The representative was given time to read the consent letter and to discuss this with the GP prior to agreeing to take part. The author recognised that it was difficult to get a representative sample from this approach and that the presence of recording could have led to an improved practice from the pharmaceutical representative. The recordings, all made one-to-one were then transcribed and analysed.

Seven GPs (out of 15 invited) made some 16 recordings. Twenty-four representatives were asked to participate, 16 agreed. The recordings covered 14 different pharmaceutical companies and, on average, four drugs were presented (range 1–14) in each encounter. The average length of interviews was almost 13 min (range 4–32 min). Several interesting points emerged from this small study. For example, 73% of the words are spoken by the representatives. A number of inaccuracies against approved product information were recorded. In some cases the information was clearly wrong, for example (correct answers are in brackets):

Oestradiol patches. Rep: ‘its not metabolised by the liver’ (mainly liver metabolism).

Azelic acid. Rep: ‘you can use this product and go out into the sun. There is no photsensitivity’ (BNF side effects: rarely photosensitive, but it does exist).

Anecdotal evidence was used in six encounters to support claims. For example, one representative is quoted as saying ‘I used it (oral steroid combination) for a while. It really is very good I think’. Another regarding the appetite suppressant dexflenfluramine ‘the patients report that they stop at the second chocolate biscuit now …instead of the eighth or ninth’.

Many practitioners use the pharmaceutical company representative as a source of drug information, yet in this study, the following problems were encountered:

  • Information was only provided on indications, dosage, administration and availability.

  • There was little, if any, information on contraindications, warnings, adverse drug reactions or special groups.

  • Omission of risk information was most obvious.

  • Thirteen of the thirty-three details contained at least one inaccuracy.

  • Product comparisons were often used and the competitor product was displayed in a way that was not helpful.

WHO advocates the provision of factual and supportable information for appropriate drug use as a right for health workers and consumers. It also supports balanced information provision where positive claims must be balanced by information on side effects, contraindications and warnings.

Medicolegal implications

Iain Chalmers, Director of the UK Cochrane Centre, argues that patients should sue when available research is not put into practice.10 He reiterates the issue that HAs and trusts have a duty to seek the relevant information for themselves and not expect it to come down the line as if by magic.

Evidence is a term widely used in the legal system, and it is likely that the concept of evidence-based medicine will influence medicolegal claims. While interventions will need to show that they are supported by ‘a reasonable body of medical opinion’, there will be the need to show that procedures and protocols are firmly underpinned with quality evidence.


Evidence-based practice is a key skill for pharmacists that needs planned and careful integration into daily activities. Such a concept can be time efficient as only those articles which are of high quality need to be read (unless of course for fun or interest). This knowledge then needs to be applied in practice at the ward level and also in dealing with individual patients.

Evidence-based Pharmacy was first published as a textbook by Phil Wiffen in 2001. The first chapter was published in Eur J Hosp Pharm 2013;20:308–12


  • Phil Wiffen is editor-in-chief of EJHP and also teaches methodology for EBM and systematic reviews.

  • Tommy Eriksson is Professor in Clinical Pharmacy and Program Director of the MSc pharmacy programme at Lund University in Sweden.

  • Hao Lu is a clinical pharmacist based at the Beijing United Family Hospital in China.



  • Competing interests None.

  • Provenance and peer review Commissioned; internally peer reviewed.