How to find a paper

1. How to find a paper • Looking for a known paper: • Field search: title, author, journal, institution, textwords, year (each has field tags) • Find a paper to answer a specific question: • A friend of yours is wondering whether she should vaccinate her 2 yr old son against measles mumps and rubella (MMR). She is concerned since she heard that the vaccine can cause autism. She wants you to help her decide.

2. Get general information quickly: • Is this drug safe for my patient? • Problem: too many articles • Problem: irrelevant articles • Problem: too few articles

3. You found a paper: is it worth reading? • Does it address an important issue? • Is it original? • Did the study test the hypothesis? • Should a different type of study been done? • Was the sample size large enough? • Were the controls appropriate? • Was the statistical analysis correct? • Were the conclusions correct? • Is there a significant conflict of interest? • Is the paper well written?

4. Problems with the study design Example: • Drug education – does it work? • Millions of $ spent on education per year • Does education reduce drug use? • What experiment would you do to test?

5. Survey class of teenagers about their use of illegal drugs Include drug education sessions in their schoolwork Survey them again to see if the % using drugs or the amount of drugs taken has gone down

6. What’s wrong with the design?

7. How would you improve the design? • Control group!

8. איך מבקרים מאמר? • Question 1: Why was the study done, and what question were the authors addressing? • Background to the research stated in the introduction • Hypothesis should be clearly stated. Stating the hypothesis in the negative = “null hypothesis” – assume there is no difference and try to disprove

9. Question 2: What type of study was done? Primary or secondary? • Primary: • Experiments (in vitro, in vivo, pre-clinical) • Clinical trials • Surveys (measure something in a group of patients, health professionals, or other sample of individuals • Secondary: • Non-systematic summary of primary studies • Systematic reviews -- summary of primary studies according to rigorous and pre-defined methodology • Meta-analyses: integration of numerical data from more than one study

10. Other types of secondary studies: • Clinical guidelines – draw conclusions from primary studies (these are usually consensus statements issued for clinicians) • Decision analyses – use primary studies to generate probability trees to help clinicians and patients make choices about management • Economic analyses: use primary studies to say whether a particular course of action is a good use of resources

11. Question 3: Was this design appropriate to the research? • Terms to look out for: • Parallel group comparison • Paired or matched comparison • Within subject comparison • Single blind • Double blind • Crossover • Placebo controlled

12. Best design depends on the field of research covered: • Therapy: efficacy of drug treatments, surgical procedures, other interventions. Best design: randomized controlled trial • Diagnosis: is a new diagnostic test valid? reliable? Best study design: cross sectional survey in which both the new test and the gold standard are performed

13. Screening: demonstrate value of test that can be applied to large populations to pick up disease at pre-symptomatic stage. Best design: cross sectional survey • Prognosis: determine what is likely to happen to someone whose disease is picked up at an early stage. Best design: longitudinal cohort study • Causation: determine whether a putative harmful agent is related to the development of illness. Best design: cohort or case-controlled study, depending on how rare the disease is. Case reports may also provide crucial information

14. Randomised controlled trials (RCT) • Allocate patients based on “flip of a coin” • Follow for specified period and analyze outcomes that you define from the outset • On average the groups should be identical – therefore differences in outcome are attributable to the intervention