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13 studyprotocol 2006

How to write a clinical study protocol

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13 studyprotocol 2006

  1. 1. How to write a study protocol EPIET, Lazareto, Menorca September 2005
  2. 2. Study protocol What is it? • Describes every step of a study • Answer relevant questions - public health problem important? - study question relevant to problem? - objectives consistent with study question? - study design achieves objectives? - sufficient power? - public health impact of the findings?
  3. 3. Study protocol: Why do it? • Check - can objectives be achieved? - is study feasible? • Ensure collect crucial information • Lay down rules for all partners (quality) • Obtain approval of ethical committee(s) • Apply for funds
  4. 4. Study protocol How to start ? • Get – good examples – ideas from similar published studies – ideas from colleagues • Use a checklist of items to include • Obtain requested format (grant application)
  5. 5. Protocol outline 1. Presentation (cover page) 2. Background and justification 3. Objectives 4. Methods 5. Ethical considerations 6. Project management 7. Timetable 8. Resources 9. References 10. Appendices
  6. 6. 1. Presentation • Title – short, accurate, concise • Investigators • Main centres • Steering committee • Summary of the protocol
  7. 7. 2. Background and justification • Statement of problem, study justification − importance of subject area • magnitude, frequency − gaps in existing knowledge − principal question(s) to be addressed − contribution of results to existing knowledge − public health use of results • Review relevant literature
  8. 8. 3. Objectives • Should answer the study question • S.M.A.R.T. Principal objective • Must be achieved • Dictates design and methods Secondary objectives • Of interest, but not essential
  9. 9. Principal objective • To determine if sharing a haemodialysis machine with an HCV infected patient is a risk factor for HCV infection. Secondary objective: • To identify failures in procedures designed to prevent cross-infection via haemodialysis machines 3. Objectives example 1
  10. 10. 3. Objectives example 2 • To estimate the current mortality, among the Internally Displaced Population present in the settlements at the time of the survey, in each of the three states of Greater Darfur region
  11. 11. Hypotheses • Translation of the objectives in terms that allow statistical testing
  12. 12. Hypotheses • Translation of the objectives in terms that allow statistical testing “The incidence of HCV infection in haemodialysis patients is higher in patients sharing machines with HCV infected patients than in patients not sharing machines with HCV infected patients”
  13. 13. Hypothesis • The current crude mortality rate in IDPs in Darfur is above 1 death per 10,000 per day CMR > 1/10,000/day
  14. 14. Protocol outline 1. Presentation 2. Background and justifications 3. Objectives 4. Methods 5. Ethical considerations 6. Project management 7. Timetable 8. Resources 9. References 10. Appendices
  15. 15. 4. Methods • Procedures to achieve objectives – what will be done? – how? • Information used to judge validity
  16. 16. 4. Methods • Study design − cohort, case-control, cross-sectional… − brief justification • Study population − definition − criteria for inclusion and exclusion − mechanisms of recruitment − accessibility, follow up, representativeness
  17. 17. 4. Methods • Sampling design − frame: district, household, persons,… − method: random, cluster, stratified,… − randomisation procedures − replacement procedures (in case of refusal) • Sample size − sample size, power calculations based on principal objective − feasibility
  18. 18. 4. Methods • Selection and definition − exposures: risk factors, protective factors, confounding factors − outcomes: definition of case and the control group • Items to be measured – scales used • e.g: smoking ? lung cancer - smoking: definition, quantification, categories - lung cancer: case definition, control group definition
  19. 19. CC study of sporadic cases of Salmonella Enteritidis infection • Exposure – consumption of custard slices • Case – a person living in South-West Wales with a laboratory confirmed infection due to S.Enteritidis in June and July 1991 • Case finding – through Public Health Laboratory; weekly notifications • Control – persons living in SW Wales in same neighborhood as cases • Control finding – random selection of people using telephone’s directory
  20. 20. Methods Data analysis plan • Structured in terms of objectives • Hypotheses tested, dummy tables • Statistical tests used, adjustment, standardisation
  21. 21. Methods Data analysis plan • Define – indicators you will need to reach objectives – data you will need to collect • Better estimates of sample size for analysis of sub groups
  22. 22. Methods Data analysis Dummy table: Food specific attack rates of Salmonella infection in a day care centre, Paris, May 1999 ill n total n AR % RR 95%CI ice-cream yes ice-cream no fruit cake yes fruit cake no pudding yes pudding no
  23. 23. Methods Data analysis Case-control study, risk factors for brucellosis in France Cases Controls OR Exposed Unexp Exposed Unexp Age group < 15 15 – 25 26 - 60 > 60 Sex M F Occupation Travel Cheese
  24. 24. 4. Methods Data collection • How − interview, observation, record review • By whom − interviewers: selection, training − level of supervision • Tools − questionnaires, recording materials − questionnaires: self or interviewer administered, face to face or telephone interview • Procedures for taking samples
  25. 25. 4. Methods Data handling • Coding − during data collection, afterwards? − by whom? • Processing − software, hardware − entry • during the study, afterwards? • single entry, double entry? • Validation and data cleaning
  26. 26. 4. Methods Pilot studies, pre-testing • No study without test − Feasibility of sampling − Data collection, measurement methods − Questionnaire • Describe how to test
  27. 27. 4. Methods Limitations • Identification of potential sources of biases − selection bias − information bias • How to deal with them − possibilities for correcting − how they will affect the results
  28. 28. Protocol outline 1. Presentation 2. Background and justifications 3. Objectives 4. Methods 5. Ethical considerations 6. Project management 7. Timetable 8. Resources 9. References 10. Appendices
  29. 29. 5. Ethical considerations • Informed consent • Confidentiality, record anonymity • Data storage and protection • Ethical committee
  30. 30. 6. Project management • Participating institutes and persons • Responsibilities and tasks of each partner • Data ownership
  31. 31. 7. Timetable Planning/organisation of the study • questionnaire design, recruitment, purchases • permission • obtain funding “Pilot study” Final study • data collection • analysis • presentation of results and write up
  32. 32. 8. Resources • Extent of this section depends on target audience • Specify − available sources − requested sources • Keep budget − reasonable − detailed − well justified
  33. 33. 9. References • Limit number of references to key articles • Follow recommended style • Vancouver www.library.soton.ac.uk/infoskills/vancouver.shtm l
  34. 34. 10. Appendices • Methodological appendices • List of definitions • Questionnaires • Introductory letters to study participants • Forms for informed consent …..
  35. 35. Common problems • Too ambitious: too many questions • Insufficient attention to literature • Poor justification − why is it important to answer this question? − what impact does it have on public health? • Poorly formulated objectives • Inappropriate analysis • Inadequate description • Absence of pilot
  36. 36. Study protocol and now…. • Good Luck !

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