1. Sifting through the evidence Sarah Fradsham

3. Types of Evidence Primary Literature Observational studies Case Report Case Series Case Control Study Cohort Study Experimental studies Randomized controlled trial ? Double blinded

4. Types of Evidence Secondary Literature Synthesizes, filters and evaluates the primary research literature. Systematic reviews Meta- analyses Evidenced based practice guidelines

5. Case Report A detailed description of a single case A way of communicating something new that has been learnt from clinical practice. Unusual presentations or complications of a known condition. New condition New way of managing a common condition First line of medical evidence. As individual cases and no control they have no statistical significance.

6. Case series Collection of case reports on the treatment of individual patients Likely with the same condition First line medical evidence As with a single case report they have little statistical validity

7. Case Control Study Patients with a specific condition are compared against people who do not have that condition. Retrospective analysis of any factors or exposures that may be associated with the development of the condition. Reliant on medical records and patient recall. Less reliable as showing even if a relationship is shown cannot prove that one factor caused the other.

8. Cohort Study Identify a group of patients already with a particular exposure or taking a particular treatment. Follow over time and compare to a similar group without exposure or treatment. Observational Not as reliable as randomised controlled trials.

9. Randomized Control Trial Carefully planned Introduce a treatment or exposure to a particular defined group of patients. Control group Blinded/ Randomisation to reduce bias- single or double blinded Can provide sound evidence of cause and effect

10. Secondary literature Systematic reviews differ from traditional review articles and the conclusions are evidenced based rather than commentary. Start with a clear question Rigorous and thorough literature review to identify, appraise and synthesize relevant studies Appraise the evidence before combing and analysing data Assess individual studies for validity Meta-analyses – Type of systematic overview Use specific methodological and statistical techniques to combine quantitative data

11. Levels of Evidence Levels of evidence 1+++ High quality meta-analyses/ systematic reviews of RCTs or RCTs with very low risk of bias 1+ Well conducted meta- analyses of RCTs/ systematic reviews of RCTs or RCTs with low risk of bias 1- as above with high risk of bias 2++ High quality systematic reviews of case control or cohort studies 2+ Well conducted case control or cohort study with low risk of confounding 2- Case control or cohort study with a high risk of confounding and a significant risk the relationship is not causal 3- Non analytical studies i.e case reports 4- expert Opinion

12. Refining search results Initial screening of titles Review of abstracts Review of full text Each stage should be done by more than one person and results compared. If disagreement about a paper then it should be included and go to the wider group for review and decision. Keep a record of how many papers at each stage and the reasons for exclusion.

13. Inclusion/ Exclusion Be specific – otherwise you’ll end up with hundreds of papers! Remember your PICO question- – Population- Dying patients- Last days/ weeks? – Intervention- Clinically assisted hydration – Control- No clinically assisted hydration – Outcome- quality of life/ symptom control/ length of life Don’t include things just because they sound interesting! Looking for good quality evidence- review articles/ case reports not high level evidence- ? Exclude Review articles vs systematic reviews May need to consider volume of evidence out their before deciding on exclusion criteria.

14. Putting it into practice