Design and Classification of Medical and Public Health Studies�Planning of Health Survey

Prof. Haroun O. Isah

MBBS, MPH, FWACP, FIMC, CMC, Cert. Stat. Epidemiol, Cert. APM

Provost

College of Medicine & Health Sciences

Bingham University, New Karu

Nasarawa State

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Introduction

• Health survey is an important aspect of Public Health and evidence based medicine.
• It reveals a lot that cannot be shown in health facility – Iceberg phenomenon
• Use extensively
• It could take several designs/forms
• Could be urban or rural community-based, involve cluster or certain target group in the community or involve household survey

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Spectrum of Survey/Research

Depends on the study design

• Very simple:
• Questionnaire survey
• Complex, elaborate and capital intensive, requiring a

lot of technological gadgets:

• Immuno-flourecent study
• Electron microscopy
• In all, detail planning is needed

Design and Classification of Medical and Public Health Studies

Methodologies in Health Survey: Deciding Methodology – 1/2

Methodologies in Health Survey: Deciding Methodology – 2/2

CORRELATIONAL

Observational vs Experimental Studies

• Observational studies: Allow nature take its cause (investigator measures but does not intervene)
• Descriptive study: focuses on the description of the occurrence of a disease in a population
• Analytical study analyses relationships between health status and other variables
• Experimental or interventional studies: involve an active attempt to change a disease determinant(e.g an exposure or a behaviour) or the progress of a disaese (through treatment)
• The studies are based on a grp which has had the experience compared with control grp which has not had the experience.

Purpose of Descriptive Epidemiology

• To generate hypothesis
• To permit evaluation of trends in health & disease and comparisons among countries and subgroups within countries.
• To provide a basis for planning, provision and evaluation of health services
• To identify problems to be studied by analytical methods and to suggest areas that may be fruitful for investigation

Case Studies (Case Series)

• Case reports: documents unusual medical occurrence and can represent the first clues to the formulation of hypothesis, generally report a new or unique findings and previous undescribed disease.
• Case series: collection of individual case reports which may occur within a fairly short time, and experience of a group of patients with similar diagnosis.
• Advantages
• Useful for hypothesis generation
• Informative for very rare disease with few established risk factors
• Usually of short duration.
• Disadvantages
• Cannot study cause and effect relationships
• Cannot assess disease frequency

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Cross-sectional Study – 1/2

• It is also called epidemiologic study or prevalence study
• It analyses (describes)data collected on a group of subjects at one point in time rather than over a period of time i.e. they survey exposure and disease at a single point in time.
• Both exposure and outcome variables are been evaluated at the same point in time(without any inbuilt directionality)
• Most sophisticated descriptive study
• It answers the question “WHAT IS HAPPENING RIGHT NOW?”

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Cross-sectional Study – 2/2

• Advantages
• Best for determining the status quo(prevalence)
• Quick
• Relatively inexpensive
• Disadvantages
• Only a snapshot at a time leading to a misinformation
• Response rate may be low ,with result not representative of the population
• Weakest observational design, (it measures prevalence, not incidence of disease). Prevalent cases are survivors
• The temporal sequence of exposure and effect may be difficult or impossible to determine
• Usually don’t know when disease occurred
• Rare events a problem. Quickly emerging diseases a problem

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Correlational Study

• A study comparing incidence/prevalence of one event against another on a global scale
• Measures that represent characteristics of entire populations are used to describe the disease in relation to some factor of interest (such as age, calendar time, food consumption, drug use and utilization of health services)
• Advantage
• Compares events among nations
• Disadvantage
• Doesn’t compare individuals, so it might lead to overgeneralization.

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Analytical Studies

• Two basic designs:
• Case – control or retrospective study
• Cohort or prospective
• NOTE
• There must be a comparison group
• No control No conclusion(NCNC)

Case Control or Case History Study – 1/2

• A group of affected people is compared to unaffected people(the control)
• It’s a LONGITUDNAL STUDY (like cohort study) because it’s a study over a period of time.
• Subjects are selected based on a particular outcome and a study backwards in time to try to detect the causes or risk factors that may have earlier been reported in a descriptive study
• Subjects are then matched and assigned into the two groups. Subject selected on the basis of disease (e.g lung cancer).
• Sometimes called a retrospective study because of the direction of study

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Case Control or Case History Study – 2/2

Advantages & Disadvantages of Case Control

• Advantages
• It is relatively easy to carry out bcos we go back to existing records in the hospital
• It is also rapid and inexpensive
• It requires comparatively few subjects
• It can assist one in studying different etiological factors
• One does not need an ethical clearance
• There is no risk to the subject
• Disadvantages
• It introduces bias
• To select an appropriate control could be difficult
• It may be difficult to distinguish between the cause of a disease and an associated factor

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Cohort Study – 1/2

• A cohort is a grp of people who have something in common and remain part of a group over an extended time
• A group of people exposed to a suspected etiological agent are compared with a matched control who have not been similarly exposed. Subject selected on the basis of exposure (aetiological factor; cigarette smoking)
• Follow-up over a period to compare the outcome
• Also a longitudinal study or prospective study

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Cohort Study – 2/2

Advantages and Disadvantages of Cohort Study

• Advantages
• There is no bias
• The risk can be calculated bcos the incidence can be calculated
• It is effective for studying rare exposures
• It allows the study of the natural history of the disease
• It assists in determining the temporal relationship between the etiological factor & the disease
• Disadvantages
• It takes a long time
• It is expensive
• Large no of subjects are needed
• There could be changes in the standard methods or diagnostic criteria

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Experimental Studies

• Studies in which 1 group is deliberately subjected to an experience compared with a control group with no similar experience
• The gold standard in medicine because it proves causality
• Can be controlled or uncontrolled

Uncontrolled Experimental Studies

• Intervention is not compared with a control
• The aim is to confirm that the Intervention made a difference

Controlled Experimental Studies

• In this study, a drug or procedure is compared to:
1. Another drug
2. Procedure
3. Placebo
4. Previously accepted tx
• The aim is to prove the difference due to treatment
• Blind trial-single or double
• Control could be:
• METHODOLOGY
2. Concurrent or parallel: randomized or non- randomized(quasi)
3. Sequential control: self controlled or cross over
4. External control

B. STUDY POPULATION

• Clinical trials
• Field trials
• Community trials

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Experimental Studies: Advantages & Disadvantages

Advantages

• Best study type
• Greatest prove of causality
• Gold standard for other design
• Least bias
• Proves best treatment or procedure efficacy

Disadvantages

• Greatest expense
• Long duration
• Unproven facts adopted by community can hinder study acceptance

Typical Progression of Study Design in Clinical Research

Planning of Health Survey

Practical Issues and Considerations

• Purpose of a health survey
• Practical issues and consideration – general
• Community entry
• Constituting a survey team
• Training of survey team
• Data collection
• Specimen collection
• Supervision
• Logistic challenges
• Data management
• Conclusion

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Performing Community Assessment

Steps in Involved – 1/3

• Step 1: Develop a Community Partnership
• Identify stakeholders
• Form a Community Partnership
• Assess partnership’s individual and organizational capacity
• Identify benefits and risks
• Step 1 Planning Worksheet – Community Partnership Organizational Chart
• Step 2: Determine your focus
• Identify and prioritize community public health needs
• Define the problem
• Create realistic and achievable goals and objectives
• Step 2 Planning Worksheet – Issues, problems, goals and objectives

Steps in Involved – 2/3

• Step 3: Identify the Information (Data) needed
• Articulate the primary questions you would like to answer
• Identify what type of data to be collected
• Identify data sources
• Step 3 Planning Worksheet – Questions, data types and Data sources
• Step 4: Determine how to get the information (Collect Data)
• Identify what new data will need to be collected
• Select the appropriate data collection method(s)
• Revisit steps 1 – 3 to make sure you’re on track
• Step 4 Planning Worksheet – Data Collection Plan

Steps in Involved – 3/3

• Step 5: Determine how to understand the information (Analyze Data)
• Check the data
• Go back to the primary assessment questions
• Reduce the amount of data
• Analyze the data
• Verify findings
• Interpret findings and draw conclusions
• Step 5 Planning Worksheet – Data Analysis Plan
• Step 6: Determine how to use and communicate results
• Identify assessment products
• Identify target audiences
• Present your findings
• Determine next steps
• Celebrate and acknowledge your work!
• Step 6 Planning Worksheet – Ways to report the results to target audiences

What a Health Survey Helps to Achieve

• Provides an understanding/basis of observations
• Enable the prediction of the occurrence of events
• Increase knowledge on the subject investigated
• Helps establish facts and provide logical scientific basis for policies which may have previously been based on impressions/assumptions
• Provide solutions to problems relating to health care practice.
• Provides ways of improving care modalities
• Enable the exploration of ways of maximizing the use of health resources in order to improve the health status of the community.

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Practical issues

• How feasible is the survey?

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• With respect to:
• Study area and population
• Time frame and financial implications
• Socio-cultural challenges

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• Involve the community in the planning and implementation

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Community Entry – 1/2

• Advocacy visits – Government, Community leaders, Opinion leaders, Political leaders, Religious heads, Youth leaders, Market leaders
• Ensure appropriate community entry – can make or mar the research
• Identify the community leaders
• Beware of intra-community conflicts
• Relating the research purpose to community leaders
• Build trust

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Community Entry – 2/2

• Know the culture of the people - norms
• Acceptable dressing code
• Mode of greeting or exchanging pleasantries
• Sincerity of purpose
• Avoid making promises that you cannot achieve – expectations from government
• Have excellent communication skills
• Be open minded
• Remain calm in the midst of hostility

Sensitization of Target Population

• Necessary for the community to understand the purpose of the study and their own roles
• Do not assume understanding by community leaders will always go down to the people
• Specify the target population
• Understanding of the principle of random selection of respondents
• Find time to clear their doubts to avoid running into ‘trouble’ during the research

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Constituting Survey Team – 1/2

• Source for recruiting personnel
• Pressure to use people nominated by politicians, community heads.
• Competence – predetermine requirements / qualifications
• Quality of research team members should not be compromised – it determines the quality of the research
• Look out for those with Experience in research - Community based work
• Local RAs and ‘imported’ RAs
• As much as possible use locally available RAs without compromising quality.
• Understand the culture
• Confidentiality may be threatened with local RAs

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Constituting Survey Team – 2/2

• Command respect in that area vs Trustworthiness
• Team leadership qualities
• Establish clear criteria for each level of research personnel before recruiting.
• Hierarchal definition: Coordinator, Field/Data managers, Logistician, Supervisor(s), RAs, ‘trackers, etc
• Role specification
• Do not hire someone you cannot fire

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Training of Survey Team - 1/2

• Adequate preparation
• Develop Training Manual
• Arrange appropriate venue
• Pretest of data collection tool – using similar population to that for the main study
• Do not compromise quality of training
• Training RAs on communication skills as important as the technical skills training
• Assess trainees (through tests)
• Train a little more than required and select the best

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Training Research Team – 2/2

• Make provision for back-up RAs (dropout during survey, poor performance, etc.)
• Make provision for practical field training (expose interviewers to scenario close to study area and population)
• Payment of trainees during training – desirable
• Training period to be as close as possible to time of commencing data collection
• Ensure standardization in translation of data collection tools to local language and adaptation to local context
• Special attention to Medical jargons and foreign culture and tradition in the research tools
• Prepare the RAs for the types of people they will have encounter with.
• Define role and line of communication

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Data collection – 1/2

• Define clearly the geographical area for the study (Use of EA / Community maps)
• Make adequate arrangement to access hard to reach areas (hilly places, flood prone areas)
• Dressing Kits for rainy season should be considered
• Household identification and sensitization
• Important to take care of cultural sensitivities in deploying research assistants
• Prepare to deal with households not within sample and wishing to participate in the study
• How to handle opinion leaders that are not included in the sampled population
• Tracking of respondents can be a challenge (movement to farm, markets, office and shops)

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Data collection – 2/2

• Best time for getting respondents at home and best time to get cooperation from respondents
• Obtaining consent from respondents – oral versus written consent (Thumb print, Signature, Witness)
• For women, permission from husbands may have to be sought
• Incentives vs inducement
• Interview respondents with enough privacy and confidentiality
• Avoid crowding around respondents
• Strike a balance between use of locally recruited interviewers and interviewers too familiar with respondents
• Field challenges on the definition of household
• Time taken for data collection should be as short as possible (do not exceed 45 mins as much as possible)

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Specimen Collection

• Specimen collection from patients – urine, stool, blood, etc. Ensure matching of specimen with the correct respondent’s code (proper labeling).
• Prepare for the challenges Invasive procedures in the community
• It is common for respondents to resist taking blood for tests. (Increases refusal rate).
• Challenges of collection of samples from the community; storage and transportation
• Prepare to take care of rumors and taboos related to specimen collection
• Usual request for hematinic by respondents in view of ‘blood taken’
• Hazardous waste handling & disposal

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Supervision

• Proper supervision is key to community based research
• Supportive supervision is critical
• Supervision should be thorough to:
• Check Interviewers’ pranks
• Interviewers challenges
• For spot check on data collection process and verification data already collected
• Supervisors need to go through collected data early to allow for early revisit where necessary
• Supervisory visits should be more on weak interviewers and hard to reach areas
• Supervisors to be expected at any time ‘I will be back’
• Supervisors role in easing RAs challenges with difficult respondents
• Supervisors role in re-stocking supplies on the field

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Logistics Challenges

• Reaching the communities
• Use of trackers

• Making appropriate transport arrangement

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• Seasonal difficulties with community based research
• Raining season vs farming
• Festivities
• Market days

Data Management

• Data collection on forms (hard copies)
• Use of IT equipment for data collection on the field
• Prompt data collection, collation and transfer to data entry points
• Detection of inconsistency and errors
• Identification of best software package: Epi-Info, STATA, SPSS
• Development of data base
• Test run the data base
• Supervision of data entry
• Put checks in the data base
• Ensure data quality
• Explore options of data entry – Single, double
• Identify options for data storage

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Feedback, Referral and Follow-up

• Identify the stakeholders and mode of the feedback
• Feedback is important for community acceptance of decision/policy that resulted from the research and for acceptance of future studies.
• Determine the medium for the feedback
• Some community members may require investigation – ethical
• Referral or follow-up for further treatment - provision for it within the study
• What happens to control group - benefits

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Ethical Consideration

• Obtaining ethical clearance
• Permission and consent
• Protection of study subject
• Protection of information
• Use of information