Introduction

Evidence-based medicine is a combination of principles and methods. When put into action, these ensure that medical decisions, guidelines and policies are based on the current best evidence about the effects of different forms of treatment and healthcare in general. With respect to medicines, it draws heavily on information from the benefit and risk (efficacy and safety) evaluation.

The concept of evidence-based medicine started in the 1950s. Before then, medical decisions were mainly based on medical training, clinical experience, and journal reading. However, studies showed that medical treatment decisions differed significantly between individual healthcare professionals (Soler & Smith, 2013). The basis was formed for implementing systematic methods to collect, evaluate and organise research data - leading to evidence-based medicine. Since its implementation, evidence-based medicine has been recognised by doctors, pharmaceutical companies, patients, Regulatory Authorities, and the general public.

Evidence-based medicine, as explained by Sackett et al. (1996), includes the conscientious, explicit and judicious use of the best evidence at the current time point. In other words, the evidence must be selected and used carefully, at the right time. Evidence is used to decide how to provide the best possible treatment to a given patient. To do this, the decision maker needs to look at knowledge from their own clinical experience along with the best evidence from controlled studies and research. Combining clinical experience and controlled studies in the decision-making process is important. Without clinical experience, the risk related to a given treatment may end up causing unwanted effects. A decision made with no clinical experience may also be wrong for an individual patient, as the population in a clinical trial might be different from the patient being treated.

The following lessons are about the factors and decisions affecting evidence-based medicine. A common approach to evidence-based medicine is based on a 5 step model:
1. Defining a clinically relevant question
2. Searching for the best evidence.
3. Assessing the quality of the evidence.
4. Acting on the evidence to form a clinical decision.
5. Evaluating the process.

Step 1 is relevant in situations where, for example, a patient consults a doctor with a complicated medical problem. The doctor then needs to search for information to find the correct diagnosis. To do so, the doctor needs to define a clinically relevant question. This might include consideration of the population affected (i.e. disease specific), the medical treatment, and the intended outcome.

Having decided upon the clinically relevant question, step 2, a search for the best evidence, must now take place. The person searching for the best evidence needs to be able to critically evaluate the quality of the information found. This is what is meant by step 3, assessing the quality of the evidence. To help with the practical use of evidence-based medicine in daily practice, review databases are available to bring information together. Information that is found can be ranked using the ‘evidence pyramid’ shown in Figure 1.

A critical assessment and ranking of the information found is important. The person looking at the information must think about its relevance to the question posed. They must also consider the benefit and risk. Often, generic (non-specific) guidelines and policies exist for whole disease areas, based on the combined evidence. Even though such guidelines are generic, the high degree of evidence is likely to help the decision-making process. Having established the framework, the evidence needs to be used to decide on a particular treatment for the patient, i.e. step 4. After doing so, the choice made needs to be critically evaluated to assess whether the intended outcome was achieved, i.e. step 5.