How to write a study protocol

EPIET, Lazareto, Menorca

September 2005

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?

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

Study protocolHow 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)

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. References10. Appendices

1. Presentation

• Title– short, accurate, concise

• Investigators

• Main centres

• Steering committee

• Summary of the protocol

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

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

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

3. Objectivesexample 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

Hypotheses

• Translation of the objectives in terms that allow statistical testing

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”

Hypothesis

• The current crude mortality rate in IDPs in Darfur is above 1 death per 10,000 per day

CMR > 1/10,000/day

Protocol outline

1. Presentation2. Background and justifications3. Objectives4. Methods5. Ethical considerations6. Project management7. Timetable8. Resources9. References10. Appendices

4. Methods

• Procedures to achieve objectives– what will be done?– how?

• Information used to judge validity

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

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

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

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

MethodsData analysis plan

• Structured in terms of objectives

• Hypotheses tested, dummy tables

• Statistical tests used, adjustment, standardisation

MethodsData 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

MethodsData 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

MethodsData 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

4. MethodsData 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

4. MethodsData handling

• Coding during data collection, afterwards? by whom?

• Processing software, hardware entry

• during the study, afterwards?• single entry, double entry?

• Validation and data cleaning

4. MethodsPilot studies, pre-testing

• No study without test

Feasibility of sampling

Data collection, measurement methods

Questionnaire

• Describe how to test

4. MethodsLimitations

• Identification of potential sources of biases selection bias information bias

• How to deal with them possibilities for correcting how they will affect the results

Protocol outline

1. Presentation 2. Background and justifications 3. Objectives 4. Methods 5. Ethical considerations 6. Project management 7. Timetable 8. Resources 9. References10. Appendices

5. Ethical considerations

• Informed consent• Confidentiality, record anonymity• Data storage and protection• Ethical committee

6. Project management

• Participating institutes and persons

• Responsibilities and tasks of each partner

• Data ownership

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

8. Resources

• Extent of this section depends on target audience

• Specify available sources

requested sources

• Keep budget reasonable

detailed

well justified

9. References

• Limit number of references to key articles

• Follow recommended style

• Vancouver

www.library.soton.ac.uk/infoskills/vancouver.shtml

10. Appendices

• Methodological appendices• List of definitions• Questionnaires• Introductory letters to study participants• Forms for informed consent

…..

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

Study protocoland now….

• Good Luck !