Overview of Diffrent types of studies in clinical research.pptx

An overview of different types of studies in clinical research and how to properly select the type of study that suits your research question

1. Different types of studies in clinical research Dr. Ahmed Elshebiny, MD Assistant Professor of Internal Medicine, Diabetes and Endocrinology, KFU, KSA Lecturer, Internal Medicine, Menoufia university , Egypt Former Clinical Research Fellow, Joslin Diabetes Center, USA

2. Key message

3. Learning Questions What does clinical research means? What are the aspects of study design? What are the differences between clinical trials, cohort, cross-sectional, case-control studies? How can you select a proper study for your research question? What are the measures of association to calculate for a particular study?

4. Clinical research The primary medical research includes: Basic medical research Translational research Clinical research Epidemiological research Dana Farber cancer Institute[Website] at https://blog.dana-farber.org/insight/2017/12/basic-clinical-translational-research-whats-difference/ Accessed 23/5/2022 Röhrig , Bernd, et al. "Types of study in medical research: part 3 of a series on evaluation of scientific publications."  Deutsches Arzteblatt International 106.15 (2009): 262.

5. Clinical research skills Reading and understanding research articles Planning a research Literature review Writing a proposal Clinical research ethics Study design and sampling Tabulation of data Statistical analysis Understanding the results Scientific writing Management of references Communication with medical journals Systematic review and metanalysis Peer reviewing Editorial tasks

6. Research designs and level of evidence Desai, V.S., Camp, C.L., Krych , A.J. (2019). What Is the Hierarchy of Clinical Evidence?. In: , et al. Basic Methods Handbook for Clinical Orthopaedic Research. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-58254-1_2

7. Study design The plan for all procedures of the study This includes but not limited to the study type Should be well established from the start Errors if happen can’t be corrected later Confounding and bias should be minimized

8. Aspects of study design Study question Study population/sample Type of study The unit of analysis (patients) The measuring technique ( e.g., laboratory , questionnaire)….Validity and Precision Sample size

9. Important concepts Outcome versus exposure Longitudinal versus transverse Forward or backward directed studies Ranganathan, Priya. "Understanding Research Study Designs." Indian Journal of Critical Care Medicine: Peer-reviewed, Official Publication of Indian Society of Critical Care Medicine 23.Suppl 4 (2019): S305.

10. Important Definitions Population and sample Variable and data point Descriptive and inferential statistics Parameter and statistic Prevalence and Incidence Prevalence ratio (PR) , odds ratio (OR) and Relative risk (RR) Bias and confounding

11. Classification of primary research studies Koppler JH, Understanding Clinical Research: Behind the statistics , An online course , Coursera available at : https://www.coursera.org/learn/clinical-research [Accessed 24/5/2022]

12. Classification of studies in clinical research

13. Observational studies Hani Tamim , Introduction for clinical research for residents , Saudi Commission for Health specialities, 2014[Online]

14. Case report and case series Guidelines To Writing A Clinical Case Report.  Heart Views . 2017;18(3):104-105. doi:10.4103/1995-705X.217857

15. Examples of case reports and case series Study 1 Study 2

16. Cross sectional studies To learn about the characteristics of a population at one point in time like a photo “snapshot” No comparison group Produce prevalence of group characteristics

17. Cross-sectional studies Hani Tamim , Introduction for clinical research for residents , Saudi Commission for Health specialities, 2014[Online]

18. Cross sectional studies Hani Tamim , Introduction for clinical research for residents , Saudi Commission for Health specialities, 2014[Online]

19. Examples of Cross-sectional study Study 3

20. Case – control studies Koppler JH, Understanding Clinical Research: Behind the statistics , An online course , Coursera available at : https://www.coursera.org/learn/clinical-research [Accessed 24/5/2022]

21. Case-control studies Hani Tamim , Introduction for clinical research for residents , Saudi Commission for Health specialities, 2014[Online]

22. Odds ratio in case-control studies Exposure Cases Controls yes a b No C d Odds of being exposed among the cases = a/c Odds of being exposed among the controls = b/d Exposure odds ratio = (a/c)/(b/d) = (a*d)/(b*c) (Cross-product ratio)

23. Examples of case-control study

24. Cohort studies( Longitudinal, Follow-up) Hani Tamim , Introduction for clinical research for residents , Saudi Commission for Health specialities, 2014[Online]

25. Prospective Cohort studies Koppler JH, Understanding Clinical Research: Behind the statistics , An online course , Coursera available at : https://www.coursera.org/learn/clinical-research [Accessed 24/5/2022]

26. Retrospective Cohort studies Koppler JH, Understanding Clinical Research: Behind the statistics , An online course , Coursera available at : https://www.coursera.org/learn/clinical-research [Accessed 24/5/2022]

27. Cohort studies Hani Tamim , Introduction for clinical research for residents , Saudi Commission for Health specialities, 2014[Online]

28. Examples of Cohort studies

29. Exercise 1 You are a clinical researcher Your hypothesis: People who smoke shisha are more likely to get lung cancer than people who do not smoke shisha. Exposure: smoking shisha Outcome: lung cancer Which of the following will be the most appropriate study type to prove or discard your hypothesis? Cross-sectional study Case-control study Prospective cohort Clinical trial

30. Exercise 1 You are a clinical researcher Your hypothesis: People who smoke shisha are more likely to get lung cancer than people who do not smoke shisha. Exposure: smoking shisha Outcome: lung cancer Which of the following will be the most appropriate study type to prove or discard your hypothesis? Cross-sectional study Case-control study Prospective cohort Clinical trial

31. Clinical trials

32. Randomization and blinding Randomization is important Blinding: Single , double and triple blinding Ethics: Prior knowledge, Informed consent, stoppage rules Hani Tamim , Introduction for clinical research for residents , Saudi Commission for Health specialities, 2014[Online]

33. Examples of Clinical trials

34. Probability sampling

35. Non-Probability sampling

36. Systematic review & Metanalysis

37. Systematic review & Metanalysis

38. Meta-analysis Koppler JH, Understanding Clinical Research: Behind the statistics , An online course , Coursera available at : https://www.coursera.org/learn/clinical-research [Accessed 24/5/2022]

39. Stages of A systematic review Form a clinical question(PICO) Register your Review(PROSPERO website) Systematic search of published and unpublished studies Decide which to include and exclude( 2 authors) Assess the risk of bias ( 2 authors) Analysis ( including the publication bias +- meta regression) Write up for publication

40. Bias in clinical research Bias is the systematic error that occurs in the design, conduct, or analyses of a study, which results in a wrong measure of association. Selection Bias Information bias Confounding Hani Tamim , Introduction for clinical research for residents , Saudi Commission for Health specialities, 2014[Online]

41. Assessment of Bias in systematic review

42. Take home message It is crucial to choose a proper study design with minimization of bias and confounding as required. Cross-sectional studies are important in detecting prevalence and the patient is seen at one point in time, but it is liable to bias and is less generalizable. It does not have control groups and is mainly descriptive. Case-control studies recruit the sample based on the outcome and look retrospectively for exposures. Cohort studies and clinical trials are very similar with the only difference being that the exposure in a clinical trial is assigned by the researchers. Systematic reviews and metanalysis have the highest levels of evidence that can be used to derive clinical practice guidelines

43. Suggested reading Hani Tamim , Introduction for clinical research for residents , Saudi Commission for Health specialities, 2014[Online] Koppler JH, Understanding Clinical Research: Behind the statistics , An online course , Coursera available at : https://www.coursera.org/learn/clinical-research [Accessed 24/5/2022] Ranganathan, Priya. "Understanding Research Study Designs."  Indian Journal of Critical Care Medicine: Peer-reviewed, Official Publication of Indian Society of Critical Care Medicine  23.Suppl 4 (2019): S305. Ranganathan, Priya, and Rakesh Aggarwal. "Study designs: Part 1–An overview and classification."  Perspectives in clinical research  9.4 (2018): 184. Röhrig , Bernd, Jean-Baptist Du Prel , and Maria Blettner . "Study design in medical research: part 2 of a series on the evaluation of scientific publications."  Deutsches Ärzteblatt International  106.11 (2009): 184. Röhrig , Bernd, et al. "Types of study in medical research: part 3 of a series on evaluation of scientific publications."  Deutsches Arzteblatt International  106.15 (2009): 262.