EPIDEMIOLOGY ITS PERSPECTIVES & APPLICATIONS 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].
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EPIDEMIOLOGY ITS PERSPECTIVES & APPLICATIONS
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]
EPIDEMIOLOGY PRESENT PERSPECTIVES
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A PHILOSOPHICAL STUDY OF HEALTH PROBLEM (SLIDES 3-11)
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AN ART OF THE POSSIBLE (SLIDES 11 - 17)
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A SCIENCE WITH WIDER APPLICATIONS (SLIDES 18-37) (OXFORD TEXT BOOK OF PUBLIC HEALTH)
PHILOSOPHICAL STUDY
SLIDES 3 TO 11
EPIDEMIOLOGY
PHILOSOPHICAL STUDY OF HEALTH PROBLEM Philosophy is that ill health is non-randomly distributed in the nature in clusters making things easier to study its various presentations. It is not just the methodology of describing its distribution and determinants. It is more than a methodology.
(OXFORD TEXT BOOK OF PUBLIC HEALTH)
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VON KIPPLING ‘S SIX HONEST SERVING MEN
WHY ?
WHAT ?
WHOM ?
WHEN ?
WHERE ?
HOW ?
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PHILOSOPHICAL APPROACH THERE IS NO SITUATION IN LIVES OF THE PEOPLE WHERE ONE CANNOT OBTAIN INFORMATION EMPLOYING THESE SIX HONEST MEN WISELY. THIS IS GENERALIZED UNIVERSAL PHILOSOPHICAL LIFE APPROACH UTILIZED IN EPIDEMIOLOGY.
EPIDEMIOLOGICAL APPROACH IS ALSO TYPICALLY PHILOSOPHICAL THE ONLY WAY TO ASK SOME QUESTIONS
ONE WAY OF ASKING OTHERS
NO WAY AT ALL TO ASK MANY (MORRIS)
WILLIAM FROST
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IT IS SOMETHING BEYOND THE USUAL FACTS OF OBSERVATION MOST OF THE TIMES , WE MAY FIND DIFFICULTY IN KNOWING THE CAUSE OF ILLNESS INSPITE OF HAVING LOT OF KNOWN AND OBSERVED FACTS. THE SECRET MAY LIE SOMEWHERE IN THE NATURE (ENVIRONMENT). TACT AND SKILL ARE REQUIRED TO THINK PHILOSOPHICALLY TO DETECT THIS SECRET. IT IS LIKE MEDICAL DETECTION AND NEEDS CREATIVE THINKING AND GENIUS LIKE SHERLOCK HOLMES.
EPIDEMIOLOGY IS APPLIED COMMON SENSE (BRETT & CASSENS ) COMMON SENSE MUST ALWAYS PREVAIL IN EPIDEMIOLOGICAL DEALINGS
.
IT IS AN INTELLIGENT WAY OF STUDYING HEALTH PROBLEM AND NEEDS COMMONSENSE.
SINCE DISEASES USUALLY OCCUR IN CLUSTERS AND IN CERTAIN PLACES, WE APPLY COMMON SENSE IN SEARCHING FOR THEIR CAUSES IF CAUSE IS NOT SECURED, WE SEARCH FOR RISK FACTORS.
PERSONAL EXPERIENCE AN EXAMPLE FOR TIMELY COMMONSENSE SOMETIMES PLACE DISTRIBUTION ALSO GIVES CLUES ABOUT A DISEASE A PERSONAL EXPERIENCE OF MINE WHILE INVESTIGATING MALARIA EPIDEMIC OF 40 FEVER CASES AND 11 DEATHS IN A VILLAGE NEAR VISAKHAPATNAM STEEL PLANT SERVES AS AN EXAMPLE. SIX CHILDREN WITH ENLARGED SPLEENS AND FEVER FOUND THERE ARE EXPECTED TO BE SUFFERING FROM MALRIA. BUT AFTER SEEING THE ADDRESS OF ONE CHILD WHO CAME FROM WEST BENGAL, INDIA WHICH IS ENDEMIC FOR VISCERAL LEISHMANIASIS, A DOUBT CAME TO MY MIND THAT WHY IT COULD NOT BE KALA AZAR.
PAST PERSPECTIVES
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1873 – PERKINS – TREATMENT OF EPIDEMICS.
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1927 – W.H. FROST – MASS PHENOMENON OF INFECTIOUS DISEASE.
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1934 – MASS PHENOMENON OF ANY DISEASE.
EPIDEMIOLOGY DESCRIBES FURNITURE OF EARTH
GOOD DEAL OF EPIDEMIOLOGY HAS A LITTLE TO DO WITH THE TESTING OR REFUTATION OF HYPOTHESIS BUT IS CONCERNED WITH THE DESCRIBING WHAT HAS BEEN CALLED THE “FURNITURE OF EARTH” STEBBING LS, PHILOSOPHY AND THE PHYSISTS, 2 ND EDITION, NEWYORK DOVEV, 1958 CHAPTER III
IT IS AN ART
SLIDES 12 TO 19
ART OF EPIDEMIOLOGY
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SKILLS OF APPROPRIATENESS, CREATIVITY & INNOVATION ARE ESSENTIAL.
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IT IS THESE ESSENTIAL SKILLS THAT MAKES EPIDEMIOLOGY MORE THAN A METHODLOGY
EPIDEMIOLOGICAL STUDY SHOULD BE LIKE MOTHER’ S TASTY FOOD EVERYONE CAN PROCURE ALL THE NICE FOOD ITEMS AND CAN ALSO LEARN VARIOUS COOKING METHODS BUT CANNOT MAKE A TASTY FOOD LIKE MOTHER BECAUSE MOTHER SELECTS THE RIGHT FOOD ITEMS (APPROPRIATENESS)YOU LIKE AND COOK THEM IN THE CORRECT WAY YOU ENJOY AND SERVES YOU WITH AFFECTION.
CREATIVITY & INNOVATION
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THAT TYPE OF ART IS ESSENTIAL IN MAKING A EPIDEMIOLOGICAL STUDY SUCCEESSFUL AND PLEASING(TASTY) TO THE NEEDY.
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IT IS JUST NOT ENOUGH TO KNOW VARIOUS EPIDEMIOLOGICAL METHODS.
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ONE MUST APPLY THEM CREATIVELY TO OBTAIN THE INFORMATION NEEDED TO UNDERSTAND THE NATURAL HISTORY OF DIEASE .
ART OF EPIDEMIOLOGY
ART OF LINKING CAUSES, CONDITIONS & FACTORS WITH HEALTH AND DISEASE OF POPULATION
CAUSES
LINKING
CONDITIONS HEALTH & DISEASE OF FACTORS POPULATIONS
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ART OF EXTRAPOLATING TWO TRIADS TO EXPLAIN VARIOUS INTERACTIONS TIME AGENT PLACE HOST ENVIRONMENT PERSON
ART OF THE POSSIBLE
NOTHING CAN BE PROVED OR ESTABLISHED 100% AS IN LABORATORY EXPERTIMENT AS IT IS POPULATION BASED.
ONLY MAXIMUM PROBABILITY CAN BE TRIED.
SO ONE SHOULD BE MODEST AND REALISTIC AND KNOW THE LIMITATIONS WHILE CARRYING OUT THE EPIDEMIOLOGICAL STUDIES.
ART OF POSSIBLE
• •
ALL THE FRUITS OF SCIENTIFIC WORK, IN EPIDEMIOLOGICAL OR OTHER DISCIPLINES, ARE AT BEST ONLY THE TENTATIVE FORMULATIONS OF A DISCRIPTION OF NATURE.
THIS TENTATIVENESS OF OUR KNOWLEDGE DOES NOT PREVENT PRACTICAL APPLICATIONS BUT SHOULD KEEP US SCEPTICAL AND CRITICAL, NOT ONLY OF EVERYONE ELSE’S WORK, BUT OUR OWN AS WELL (OXFORD TEXT BOOK OF PUBLIC HEALTH)
A SCIENCE
SLIDES 20-41
A SCIENCE
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IT FOLLOWS ALL THE BASIC TENETS OF SCIENCE IT HAS AN ORDER AND DEFINITE PURPOSE IT HAS SEQUENCE, RELAVANCE, INFERENCE AND IS SYSTEMATIC IT FOLLOWS ETHICS IT HAS WIDER & ACCEPTABLE APPLICATIONS
EPIDEMIOLOGY IS BOTH THE BASIC SCIENCE OF PUBLIC HEALTH AND ITS MOST FUNDAMENTAL PRACTICE
MAXCY
LANGMUIR ON EPIDEMIOLOGICAL PRACTICE
SURVILLANCE, EPIDEMIOLOGICAL INVESTIGATIONS COUNT CASES & MEASURE THE POPULATION AFFECTED DETECTS, INVESTIGATES & ANALYZES PROBLEMS DISSEMINATION TO HELATH PLANNERS & PUBLIC RESULTING INFORMATION APPLIED FOR PREVENTION & CONTROL EVALUATION HEALTH PROGRAMS HEALTH POLICY
OBJECTIVES OF EPIDEMIOLOGY DISEASE LOAD AIM OF EPIDEMIOLOGY FOR TAKING H E A L T H A C TI O N CAUSE EDUCATION AL & RESEARCH
RIGHT HAND OF COMMUNITY MEDICINE
COMMUNITY MEDICINE EPIDEMIOLOGY BIOSTATISTICS
EPIDEMILOGY PROVIDES INTELLIGENCE FOR HEALTH ACTION
INTELLIGENCE MEANS INFORMATION REGARDING THE DETERMINANTS OF HEALTH & DISEASE AND THEIR OCCURRENCE & MAGNITUDE IN POPULATIONS FOR TAKING HEALTH ACTION J. N. MORRIS
EPIDEMIOLOGICAL PURPOSE & SEQUENCE
1.
2.
3.
4.
5.
IDENTIFYING DISEASE/ HEALTH PROBLEM LINKING WITH THE CAUSE / RISK FACTORS ESTABLISHING CAUSAL RELATION- SHIP DESIGNING AN INTERVENTION FOR CONTROLLING PROBLEM TO EVALUATE THE EFFECTIVENESS OF INTERVENTION (MAXCY)
MORRIS’ SEVEN USES
1.
2.
3.
4.
5.
6.
7.
TREND STUDY COMMUNITY DIAGNOSIS HEALTH SERVICES EVALUATION TO KNOW THE INDIVIDUAL RISKS AND CHANCES SYNDROME IDENTIFICATION COMPLETING THE CLINICAL PICTURE SEARCHING FOR CAUSES / RISK FACTORS FOR ESTABLISHING CAUSAL RELATIONSHIP
TREND STUDY
1.
STUDYING THE PAST HISTORY FOR RISE AND FALL 2.
STUDYING ITS CHANGING BEHAVIOUR 3.
MAKING FUTURE PREDICTIONS 4.
GIVING EARLY WARNINGS OR FEED BACK
COMMUNITY DIAGNOSIS
SOCIAL ANATOMY SOCIAL PHYSIOLOGY SOCIAL PATHOLOGY COMMUNITY DIAGNOSIS QUALITATIVE ESTIMATION QUANTIFICATION
COMMUNITY DIAGNOSIS
1.
2.
3.
SOCIAL ANATOMY : RACE, AGE AND SEX COMPOSITION, SOCIO ECONOMIC STATUS, POPULATION AT RISK, RESOURCES AVALAIBLE.
SOCIAL PHYSIOLOGY : POSITIVE &NEGATIVE LIFESTYLES, OCCUPATION, HEALTH SERVICES AWARENESS AND UILIZATION, NUTRITIONAL POLICES, LABOUR.
SOCIAL PATHOLOGY : MORBIDITY, MORTALITY, DISABILITY, ALCHOLISM, SMOKING, CRIME & VOILENCE, RISK PRONE BEHAVIOUR.
COMMUNITY DIAGNOSIS
MUST BE DYANAMIC IN A WORLD OF CHANGE, EPIDEMIOLOGIST HAVE A SPECIAL DUTY TO OBSERVE THE IMPACT “UPON THE PEOPLE” AND THE WAY WE LIVE TO DIAGNOSE WHERE WELL -BEING IS INCREASING AND WHERE LOSING OUT, TO PROBE FOR UNINTENDED CONSEQUENCES , TO IDENTIFY TRENDS AND TO THINK AHEAD.
ONION PRINCIPLE
JUST LIKE THE LAYERS OF THE ONION, THE OLD DISEASES WANE AND GIVE PLACE TO NEWONES.
INFECTIOUS ONES WILL BE REPLACED BY NON – INFECTIOUS ONES TO BE REPLACED LATERBY PERSONAL AND BEHAVIORAL PROBLEMS.
ONE MUST BE AWARE OF THIS PHENOMENON BEFORE DIAGNOSING THE OLD DISEASES COMMUNITY HEALTH
HEALTH SERVICES EVALUATION
HEALTH PLANNING FOR
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APPROPRIATE COST EFFECTIVE COMMUNITY NEED BASED JUDICIAL MIX OF PREVENTIVE, PROMOTIVE, CURATIVE, REHABILITATIVE AND PUBLIC HEALTH SERVICES
SYNDROME IDENTIFICATION LUMPERS & SPLITTERS
GROUPING AND DIVIDING THE SYMPTOM- COMPLEXES AND NAMING THEM AS SYNDROMES IS THE STARTING POINT FOR THE STUDY OF NATURAL HISTORY OF ANY DISEASE
SEARCH FOR CAUSES
SEVERAL CAUSES
SINGLE DISEASE SINGLE CAUSE
SEVERAL DISEASES SEARCH FOR CAUSE IN INTERRELATED DISEASES MAY YIELD CLUES FOR NEW CAUSES / RISK FACTORS
COMPLETING THE CLINICAL PICTURE
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IN BREADTH OF DISEASE HOSPITAL STUDIES HAS TO BE BROADEND WITH SIMULTANEOUS COMMUNITY STUDIES AS THEY POORLY REPRESENT THE HELTH EVENT IN GENERAL POPULATION. MERE DEPENDENCE ON STUDIES CONDUCTED IN HOSPITAL OR ANY HEALTH FACILITY SETTING IS BIASED BECAUSE THEY DO NOT INCLUDE THE PREPATHOGENIC AND FOLLOW-UP PHAGES OF THE DISEASE STUDIED.
• • • • • • •
IN DEPTH GOING TO THE BOTTOM, THE DEEEPER PART OF THE ICEBERGH TO STUDY THE EARLIER PART OF DISEASE, WHICH IS EITHER STOPPABLE OR ATLEAST PREVBENTABLE BY SEARCHING FOR PRECURSORS OF THE DISEASE DISPOITIONS DUE TO DISEASE ASYMPTOMATIC DISEASE SUBCLINICAL CASES LATENT CASES CARRIER STATE
NATURAL HISTORY OF DISEASE
RISK ASSESMENT
INDIVIDUAL RISK GENERAL POPUTLATION RISK PROGNOSIS FOR BY PHYSICIAN
CYCLE OF EXTENSION
DISEASE IN MAN MAN
TB
INFLUENCING ENVIRONMENT
SCOPE AND JURISDICTION
STRICTLY SPEAKING, THERE IS NO LIFE SCIENCE, WHERE EPIDEMIOLOGICAL APPROACH AND PRINCIPLES CANNOT BE APPLIED
FROM WOMB TO TOMB EPIDEMIOLOGY IS APPLICABLE
PREVENTIVE PAEDIATRICS PREVENTIVE GERIATRICS PREVENTIVE CARDIOLOGY CLINICAL EPIDEMIOLOGY