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  • APCRC
  • West
  • NHS

What is evidence?

As a commissioner, a manager of a service, a clinician, a researcher, or a service user you may need look for the latest evidence about an area of health and social care you are involved in. This might be to inform a decision about funding, or about changes and improvements, or to inform an evaluation or an individual decision about your choices as a patient. So what does evidence mean in this context? Evidence can refer to a range of different sources of information about an intervention, service or care that could help inform a decision about it. Research papers, guidelines, evaluations, population and surveillance data, policy, health needs assessments, activity data, feedback from stakeholders, patients, carers and the public are all sources of evidence.

This toolkit aims to support you in accessing evidence from a range of sources but has a particular focus on locating evidence from research as this can be under-utilised in decision-making.

What type of evidence is best?

You may have come across the concept of an evidence hierarchy in healthcare. As it originates from the evidence-based medicine movement, it is based on the best research designs for questions about effectiveness – i.e., whether something works – which places designs such as randomised controlled trials and systematic reviews of trials, at the top. This encourages a focus only on certain types of evidence. But if we’re asking a different sort of question, that hierarchy isn’t appropriate and we might overlook useful evidence. For example, if we want to know about patients’ experiences of a service or care received, then we will need evidence from qualitative research or evaluation.

It is more helpful to consider the question you are asking and what type of evidence is likely to help you answer it, more in the style of a matrix like in Table 1 in this article. This will help you embrace all the possible evidence that might be helpful, rather than just evidence from certain types of research.

Tip: If you want help with understanding different research designs there is more detail in this guide.

Case study: What difference does evidence make?

This local case study illustrates the value of evidence in helping reduce inequalities in health and improve health outcomes in our population.

The question: What is the best approach to prevent and treat alcohol-related malnutrition in people who are homeless, or at risk of becoming homeless? What can help prevent or reverse micronutrient deficiencies in this group of people?

The evidence: A thorough search for published research involving homeless drinkers was carried out to find evidence on the type and level of nutrient deficiencies and to look at effective treatments to reduce or cure these deficiencies. The quality of the research was assessed as part of this process.

What was found: Although evidence was limited, nine studies were located which showed that there are deficiencies including vitamin B1 and many other micronutrients. Evidence also showed 25 different types of treatment for reducing malnutrition in this population. These included educating homeless people on better eating and drinking less, providing food or vitamin supplements or help with detox, or a combination of these approaches.

The conclusion: The best way to improve nutrition in this population is through provision of food, supplements or cooking facilities, either alone or in combination with other treatments. Involving participants in setting up interventions can lead to good uptake.

“Research can do more than contribute to better decisions – it can change the way we think about issues or problems and stimulate new and different ideas about services. In short, it’s vital to our capacity for innovation.”

Professor K Walshe
Associate Director of the National Institute of Health Research

“Evidence based medicine is the integration of best research evidence with clinical expertise and patient values”

Sackett D et al
Evidence-Based Medicine: How to Practice and Teach EBM, 2nd edition. Churchill Livingstone, Edinburgh, 2000, p.1