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How to write a study protocol EPIET, Lazareto, Menorca September 2005.

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Presentation on theme: "How to write a study protocol EPIET, Lazareto, Menorca September 2005."— Presentation transcript:

1 How to write a study protocol EPIET, Lazareto, Menorca September 2005

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 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 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 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 1. Presentation Title –short, accurate, concise Investigators Main centres Steering committee Summary of the protocol

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 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 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 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 Hypotheses Translation of the objectives in terms that allow statistical testing

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 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 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 4. Methods Procedures to achieve objectives –what will be done? –how? Information used to judge validity

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 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 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 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 telephones directory

20 Methods Data analysis plan Structured in terms of objectives Hypotheses tested, dummy tables Statistical tests used, adjustment, standardisation

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 Methods Data analysis Dummy table: Food specific attack rates of Salmonella infection in a day care centre, Paris, May 1999

23 Methods Data analysis Case-control study, risk factors for brucellosis in France

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 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 4. Methods Pilot studies, pre-testing No study without test Feasibility of sampling Data collection, measurement methods Questionnaire Describe how to test

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 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 5. Ethical considerations Informed consent Confidentiality, record anonymity Data storage and protection Ethical committee

30 6. Project management Participating institutes and persons Responsibilities and tasks of each partner Data ownership

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 8. Resources Extent of this section depends on target audience Specify available sources requested sources Keep budget reasonable detailed well justified

33 9. References Limit number of references to key articles Follow recommended style Vancouver www.library.soton.ac.uk/infoskills/vancouver.shtm l

34 10. Appendices Methodological appendices List of definitions Questionnaires Introductory letters to study participants Forms for informed consent …..

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 Study protocol and now…. Good Luck !


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