Download EXPERIMENTAL EPIDEMIOLOGY

COMMUNITY
INTERVENTION TRIALS
AUTHOR
Dr. A. K. AVASARALA
MBBS, M.D.
PROFESSOR & HEAD
DEPT OF COMMUNITY
MEDICINE & EPIDEMIOLOGY
PRATHIMA INSTITUTE OF
MEDICAL SCIENCES,
KARIMNAGAR, A.P..
INDIA: +91505417
[email protected]
PROMPT
• I WISH TO DEVELOP AN
EPIDEMIOLOGY COURSE FOR
TEACHING, AS THERE IS GOOD
RESPONSE, NATIONALLY AND
INTERNATIONALLY FROM THE
FACULTY TEACHING
EPIDEMIOLOGY, FOR MY
PREVIOUS THIRTEEN
EPIDEMIOLOGY LECTURES
LEARNING OBJECTIVES
1. READER IS EXPECTED TO
LEARN THE NATURE & SCOPE
OF COMMUNITY INTERVENTIONS
2. THE PRECAUTIONS AND STEPS
IN CONDUCTING COMMUNITY
TRIALS
3. ABLE TO ANALYSE AND
INTERPRET THE RESULTS
PERFORMANCE OBJECTIVES
• READER CAN DESIGN AND
PERFORM COMMUNITY
INTERVENTION TRIALS
• HE CAN PROMOTE THE
HEALTH OF THE COMMUNITY
AS A WHOLE BY RISK FACTOR
REDUCTION TRIALS
TYPES
• PRIMARY PREVENTIVE
TYPE (COMMUNITY
INTERVENTION TRIALS (CIT)
NATURE OF STUDIES
• INTERVENTION STUDIES
• NOT JUST OBSERVATIONS
• EXPERIMENTATIONS
COMMUNITY INTERVENTION
TRIALS (CIT )
• THE MAIN PURPOSE IS TO
REDUCE THE OCCURRENCE
OF DISEASES AND DEATHS
EARLY IN LIFE IN THE WHOLE
COMMUNITY, HENCE THE
NAME.
WHY CIT ?
REDUCTION IN RISK
FACTORS
IMPACT ON
.
THE HEALTH STATUS OF
A COMMUNITY.
CHANGE TO HEALTHIER LIFESTYLE LEADS
TO
BY HIGH-RISK GROUPS
CHANGE THE
BEHAVIOR OF OTHER MEMBERS
OF THE SOCIETY
INTERVENTIONS AIMED AND FOCUSED
THE INCIDENCE OR
AFFECT COURSE OF OTHER DISEASES.
AT SPECIFIC DISEASES
ENHANCE
HEALTH ACTIVITIES
IN COMMUNITIES
THE CONFIDENCE IN THE PEOPLE
AND THEREBY THEIR INVOLVEMENT
AND ACCEPTANCE
GENERAL OBJECTIVES
•TO INCREASE HEALTH KNOWLEDGE
OF THE WHOLE COMMUNITY ,
• TO DEVELOP POSITIVE AND RIGHT ATTITUDE
•IN THE COMMUNITY
• TO
INCREASE THE PRACTICE OF POSITIVE
HEALTH BEHAVIOR OF THE WHOLE COMMUNITY
•THEREBY PREVENTING EARLY DISEASES
AND DEATHS IN THE COMMUNITY
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SPECIFIC OBJECTIVES
TO MEASURE VERIFIABLE CHANGES IN:
1. HEALTH KNOWLEDGE IMPROVEMENT
2. ATTITUDE
3. BEHAVIOR
STEPS OF CONDUCTING CIT
1.
2.
3.
4.
5.
SETTING
STUDY DESIGN
INTERVENTION METHODS
EVALUATION OF INTERVENTION
LIMITATIONS OF STUDY
IDEAL SETTING
• COMMUNITY IS THE
IDEAL SETTING
STUDY DESIGN
• QUASI - EXPERIMENTAL TYPE
THE INVESTIGATOR WILL NOT BE
HAVING AS MUCH OF A CHANCE OF
RANDOM ALLOCATION OF THE
INDIVIDUALS TO THE TWO GROUPS
AS IN CLINICAL TRIALS.
SELECTION OF REFERENCE
AND INTERVENTION
POPULATIONS
• DESIRABLE TO HAVE ALMOST
IDENTICAL REFERENCE AND
INTERVENTION POPULATIONS
TO GET THE VALID RESULTS
OUT OF COMMUNITY TRIALS.
NESTED OR EMBEDDED
DESIGN
REFERENCE POPULATION
Pooled intervention
EMBEDDED DESIGN
EMBEDDED TYPE WILL HELP
• IN REDUCING SECULAR
DIFFERENCES
• IN REDUCING CONFOUNDING
BIAS AS THE BOTH KNOWN
AND UNKNOWN VARIABLE
FACTORS WILL BE EQUALLY
DISTRIBUTED IN BOTH THE
POPULATIONS.
REFERENCE POPULATION
THE ONE WITH WHICH THE
RESULTS OBTAINED FROM
THE TRIAL ON THE
INTERVENTION POPULATION
ARE COMPARED, ANALYZED,
INTERPRETED AND UTILIZED
FOR PREPARING PUBLIC
HEALTH POLICY.
INTERVENTION POPULATION
• THE EXPERIMENTAL POPULATION
RANDOMLY SELECTED FROM A
COUNTRY OR REGION AND
ALMOST IDENTICAL AND
COMPARABLE WITH THE
REFERENCE (CONTROL)
POPULATION IN POSSESSING ALL
ITS CHARACTERISTICS.
UNDERSTANDING SOCIETAL
CONDITIONS
•
•
•
•
•
•
COMMONNESS OF TERRITORY,
MORTALITY PATTERN,
MORBIDITY PATTERN,
FERTILITY PATTERN,
CUSTOMS ,
SECULAR TRENDS
COLLECTING BASE LINE
INFORMATION
• PREPARING THE BASE LINE
LEVELS OF RISK FACTORS,
MORTALITY RATES
INTERVENTION CONCEPT
• IDEA IS TO BRING ABOUT THE
ATTITUDINAL CHANGE IN THE
PEOPLE TO ALTER THEIR
NEGATIVE LIFE STYLES AND TO
SUSTAIN.
• THIS CAN BE ACHIEVED BY
MEANS OF THE FOLLOWING
SOCIAL SKILL LEARNING
TECHNIQUES.
INTERVENTION BY SOCIAL
COGNITION/LEARNING
SOCIAL COGNITION/LEARNING
WHEREIN THE CHANGE OF
BEHAVIOR CAN BE ACHIEVED
THROUGH INTENSIVE
EXPOSURE TO IMPORTANT
MODELS LIKE POP STARS,
PLAYERS.
INTERVENTION BY REASONED
ACTION AND PLANNED
BEHAVIOR
WHERE THE CHANGE CAN BE
BROUGHT ABOUT BY ADAPTING THE
INFORMATION GIVEN BY CREDITABLE
PERSON FIRST AND SUSTAINING IT BY
SELF MANAGEMENT LATER I.E. BY
LEARNING THE NECESSARY SKILLS.
INTERVENTION BY
PERSUASIVE COMMUNICATION
• CONTINUOUS PERSUASIVE
COMMUNICATION TO THE
PEOPLE THROUGH MASS MEDIA
LIKE MOVIES, TELEVISION ETC
TO CONVINCE THEM TO ADOPT
POSITIVE LIFE STYLES CAN
ALSO BRING ABOUT A CHANGE
IN LIFE STYLE.
PRECEDE-PROCEED MODEL
INTERVENTION
The PRECEDE process
• Predisposing,
• Reinforcing, and
• Enabling
• Constructs in
• Educational-environmental
• Diagnosis and
• Evaluation)
PROCEED process follows with
implementation, process, and impact
and outcome evaluation.
SOCIAL MARKETING
INTERVENTION
• PREVENTIVE HEALTH SERVICES ARE
THE PRODUCTS TO BE MARKETED
AND THE TARGET AUDIENCE, COSTS
AND BENEFITS HAVE TO BE DEFINED.
• PROPER MESSAGES HAVE TO BE
DEVELOPED AND EFFECTIVE
CHANNELS FOR ACCEPTANCE HAVE
TO BE SELECTED.
EVALUATION OF INTERVENTION
• ENDPOINTS TO BE MEASURED
1. CHANGES IN KNOWLEDGE, ATTITUDE AND
PRACTICE
2. MEANS AND PREVALENCES OF RISK
FACTORS
3. SYMPTOMS/SIGNS/PAIN REDUCTION
4. SPECIFIC MORBIDITY (OBTAINED FROM
PRACTITIONERS, HOSPITALS, AVAILABILITY
OF MEDICAL SERVICES AND TREATMENT)
5. SPECIFIC MORTALITY RATES OF THE MOST
COMMON DISEASES
6. TOTAL MORTALITY IN THE BOTH
COMMUNITIES
EVALUATION METHODS
• POPULATION SURVEYS ARE
CARRIED OUT BOTH IN THE
REFERENCE AND INTERVENTION
POPULATIONS SIMULTANEOUSLY
THRICE I.E. BEFORE, DURING
AND AFTER THE INTERVENTION.
TECHNIQUES OF MEASUREMENT
• QUESTIONNAIRES – ORAL WRITTEN,
OR COMPUTERIZED ONES ARE USED
DURING THE SURVEYS
• *ANALYTICAL METHODS –
LABORATORY TESTS FOR PHYSICAL
AND BIOCHEMICAL PARAMETERS BY
TRAINED PERSONNEL DONE BEFORE
AFTER CIT TO AVOID OBSERVER
VARIATION
ROSENTHAL EFFECT
• THE INDIVIDUAL’S NATURE OR
PREFERENCE TO ENHANCE OR
REDUCE THE VALUE OF THE
ENDPOINT WHILE TESTING OR
READING THE LABORATORY
FINDINGS BECAUSE OF HIS
PERSONALITY INFLUENCE HAS
ALSO TO BE TAKEN CARE OFF.
CEILING EFFECT
• CEILING EFFECT IS SAID
TO BE PRESENT IN THE
COMMUNITY WHEN A
PART OR WHOLE OF THE
COMMUNITY POSSESSES
PERSONS AT HIGH RISK.
PRECAUTIONS:
1. NET CHANGES ARE MEASURED
UNIFORMLY IN A STANDARDIZED
AND SIMILAR MANNER IN BOTH THE
REFERENCE (CONTROL) AND
INTERVENTION POPULATIONS
2. INITIAL DIFFERENCES BETWEEN
THE TWO POPULATIONS HAVE TO
BE GIVEN DUE CONSIDERATION.
THESE MAY BE DUE TO CHANCE OR
REGRESSION TO THE MEAN.
INTENTION TO TREAT
PRINCIPLE
• THE “INTENTION TO TREAT”
PRINCIPLE, THAT IS, ONCE
RANDOMIZED, ALWAYS
ANALYZED – IS TO BE
STRICTLY FOLLOWED
NET CHANGE MEASUREMENT
I0
R1
RELATIVE
CHANGE
RISK
FACTOR
LEVEL
R0
BASE-LINE
I1
FINAL SURVEY
MULTIVARIATE
REGRESSION MODEL
• FORMULA:
Y = AGE + TIME1 +TIME2
+(COMMUNITY * TIME1)
+(COMMUNITY * TIME2)
FACTORS AFFECTING THE
EVALUATION:
1. DELAY OF THE DEVELOPMENT OF
THE RISK FACTORS HINDERS THE
EVALUATION
1. INTENSITY AND DENSITY OF
INTERVENTION DETERMINES THE
EVALUATION STRATEGY
1. STATISTICAL POWER OF THE
SAMPLES DETERMINES EVALUATION
THE SUCCESS OF CIT
1. THE SOCIETAL CONDITIONS AND
ENVIRONMENT
2. AVAILABILITY OF THE OTHER HELPING
SOCIAL HEALTH STRUCTURES
3. POSITIVE PREVENTIVE CLIMATE
4. THE NEED FOR THE TRIAL MUST BE
FELT BY THE COMMUNITY AS A DIRE
NECESSITY
5. PRACTICAL FEASIBILITY, FINANCIAL
AND TIME CONSTRAINTS
LIMITATIONS-1
• THE RANDOMIZATION CAN NOT
BE ACHIEVED STRICTLY
The sampling method may be
having inherent error or the
sampled communities may be
having inherent differences which
can, of course, be minimized with
difficulty.
LIMITATIONS-2
• CHANGES IN MORTALITY AND
MORBIDITY TAKE SEVERAL YEARS
TO OCCUR
Though it is true to larger extent
particularly with the non-infectious
diseases, biochemical/ risk factors
changes may be seen comparatively
earlier in the intervention community.
EFFECT OF IMMIGRATION INTO
AND EMIGRATION
• IMMIGRATION INTO AND EMIGRATION
FROM ANY OF THE TWO COMMUNITIES
UNDER TRIAL WILL AFFECT THE
EVALUATION AND TRIAL OBJECTIVES.
• ONLY THE LIVING PART OF THE
COMMUNITY CAN SERVE AS THE
USEFUL DENOMINATOR FOR CORRECT
ASSESSMENT. HENCE MIGRATION
FACTOR HAS TO BE GIVEN DUE
CONSIDERATION.
PERSONAL EXPERIENCE
COMMUNITY FLUORIDATION
FOR DENTAL CARIES 1990
• START / DURATION: 1992,
5 YEARS
• POPULATION: 8000, SHIELANAGAR,
VISAKHAPATNAM,
• INTERVENTION: FLOURIDATION OF
MUNICIPAL WATER SUPPLIES.
NORTH KARELIA PROJECT
• START / DURATION: 1972;
10YEARS INTERVENTION.
• POPULATION: 180000
INHABITANTS, AGES 25–59
YEARS.
• INTERVENTION: COMPREHENSIVE
COMMUNITY INTERVENTION,
REDUCTION OF ARDIOVASCULAR
RISK FACTORS.
CORONARY RISK FACTOR
STUDY (CORIS)
• START / DURATION: 1979; 4 YEARS
OF INTERENTION.
• POPULATION: 11700 WHITE
PERSONS, AGES 15 – 64 YEARS.
• INTERVENTION: COMPREHENSIVE
COMMUNITY INTERVENTION, SMALL
MASS MEDIA AND INTERPERSONAL
(HIGH INTENSE) INTERVENTION;
REDUCE CHOLESTOAL BP, SMOKING
STRESS, INCREASE PHYSICAL
ACTIVITY.
STANFORD FIVE CITY PROJECT
• START / DURATION: 1980;
5 YEARS INTERENTION.
• POPULATION: 122800, AGES
12 – 74 YEARS.
• INTERVENTION: COMPREHENSIVE
COMMUNITY INTERVENTION,
REDUCE CHOLESTEROL, BP,
SMOKING, WEIGHT, INCREASE
PHYSICAL ACTIVITY.
MINNESOTA HEART HEALTH
PROGRAM
• START / DURATION: 1980: 5 – 6 YEARS
OF INTERVENTION.
• POPULATION: 231000 ADULTS.
• INTERVENTION: IMPROVE HEALTH
BEHAVIOUR, REDUCE CHOLESTROL,
7 MG/DL, BP 2MMHG, SMOKING 3%,
INCRESE PHYSICAL ACTIVITY 50KCAL
/DAY, REDUCE CARDIOVASCULAR
DISEASE MOBIDITY AND MORTALITY
15%.
PAWTUCKET HEART HEALTH
STUDY
• START / DURATION: 1981,
7 YEARS INTERVENTION.
• POPULATION: 72000 WORKING
CLASS PEOPLE.
• INTERVENTION: COMMUNITY
ACTIVATION
CONCLUSIONS
• DUE TO OUR INTERVENTIONS,
REDUCTION IN HARMFUL
LIFESTYLES/RISK FACTORS
WILL OCCUR THEREBY
LEADING TO THE REDUCTION
IN MORBIDITY, MORTALITY OR
DISABILITY RATES.
REFERENCES
• Brian Mac Mahan - Epidemiology:
principles & methods
• Roger Detels, James Mc Even-Oxford
Text Book of Public Health
• Maxcy-Rosenau-Last, Public Health &
Preventive medicine
• Brett & Cassens- Public Health
Medicine,National Student Series.