EPIDEMIOLOGY - ITS PERSPECTIVES

1
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
avasarala_at_yahoo.com
2
EPIDEMIOLOGY- PRESENT PERSPECTIVES

• A PHILOSOPHICAL STUDY OF HEALTH
• PROBLEM (SLIDES 3-11)
• AN ART OF THE POSSIBLE (SLIDES 11 - 17)
• A SCIENCE WITH WIDER APPLICATIONS
• 
  (SLIDES 18-37)
• (OXFORD TEXT BOOK OF PUBLIC HEALTH)

3
PHILOSOPHICAL STUDY
SLIDES 3 TO 11
4
EPIDEMIOLOGY

• PHILOSOPHICAL
• STUDY
• OF
• HEALTH
• PROBLEM
• (OXFORD TEXT BOOK OF PUBLIC HEALTH)

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.
5
VON KIPPLING S SIX HONEST SERVING MEN

• 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.

• WHY ?
• WHAT ?
• WHOM ?
• WHEN ?
• WHERE ?
• HOW ?

6

• 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)
7
WILLIAM FROST
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.

• IT IS
• SOMETHING BEYOND THE USUAL
  FACTS OF OBSERVATION

8
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.
9
PERSONAL EXPERIENCEAN 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.
10
PAST PERSPECTIVES

• 1873 PERKINS TREATMENT OF EPIDEMICS.
• 1927 W.H. FROST MASS PHENOMENON OF
  INFECTIOUS DISEASE.
• 1934 MASS PHENOMENON OF ANY DISEASE.

11
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, 2ND
EDITION, NEWYORK DOVEV, 1958 CHAPTER III
12
IT IS AN ART
SLIDES 12 TO 19
13
ART OF EPIDEMIOLOGY

• SKILLS OF APPROPRIATENESS,
• CREATIVITY INNOVATION
• ARE ESSENTIAL.
• IT IS THESE ESSENTIAL SKILLS THAT MAKES
  EPIDEMIOLOGY MORE THAN A METHODLOGY

14
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.
15
CREATIVITY INNOVATION

• THAT TYPE OF ART IS ESSENTIAL IN MAKING A
  EPIDEMIOLOGICAL STUDY SUCCEESSFUL AND
  PLEASING(TASTY) TO THE NEEDY.
• IT IS JUST NOT ENOUGH TO KNOW VARIOUS
  EPIDEMIOLOGICAL METHODS.
• ONE MUST APPLY THEM CREATIVELY TO OBTAIN THE
  INFORMATION NEEDED TO UNDERSTAND THE NATURAL
  HISTORY OF DIEASE.

16
ART OF LINKING CAUSES, CONDITIONS FACTORS WITH
HEALTH AND DISEASE OF POPULATION
ART OF EPIDEMIOLOGY
CAUSES CONDITIONS FACTORS
HEALTH DISEASE OF POPULATIONS
LINKING
17

• ART OF EXTRAPOLATING TWO TRIADS
• TO EXPLAIN VARIOUS INTERACTIONS

TIME
AGENT
HOST
ENVIRONMENT
PLACE
PERSON
18
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.

19
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
  ELSES WORK, BUT OUR OWN AS WELL

(OXFORD TEXT BOOK OF PUBLIC HEALTH)
20
A SCIENCE
SLIDES 20-41
21
A SCIENCE

• 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

22

• EPIDEMIOLOGY IS BOTH THE BASIC SCIENCE OF PUBLIC
  HEALTH AND ITS MOST FUNDAMENTAL PRACTICE

MAXCY
23
LANGMUIR ON EPIDEMIOLOGICAL PRACTICE
DETECTS, INVESTIGATES ANALYZES PROBLEMS
COUNT CASES MEASURE THE POPULATION AFFECTED
SURVILLANCE, EPIDEMIOLOGICAL INVESTIGATIONS
RESULTING INFORMATION APPLIED FOR PREVENTION
CONTROL
DISSEMINATION TO HELATH PLANNERS PUBLIC
EVALUATION
HEALTH PROGRAMS
HEALTH POLICY
24
OBJECTIVES OF EPIDEMIOLOGY
FOR TAKING
25
RIGHT HAND OF COMMUNITY MEDICINE
COMMUNITY MEDICINE
EPIDEMIOLOGY
BIOSTATISTICS
26
EPIDEMILOGY PROVIDESINTELLIGENCEFOR HEALTH
ACTION
INTELLIGENCE MEANS INFORMATION REGARDING THE
DETERMINANTS OF HEALTH DISEASE AND THEIR
OCCURRENCE MAGNITUDE IN POPULATIONS FOR TAKING
HEALTH ACTION
J. N. MORRIS
27
EPIDEMIOLOGICAL PURPOSE SEQUENCE

1. IDENTIFYING DISEASE/ HEALTH PROBLEM
2. LINKING WITH THE CAUSE / RISK FACTORS
3. ESTABLISHING CAUSAL RELATION- SHIP
4. DESIGNING AN INTERVENTION FOR CONTROLLING PROBLEM
5. TO EVALUATE THE EFFECTIVENESS OF INTERVENTION

(MAXCY)
28
MORRIS SEVEN USES

1. TREND STUDY
2. COMMUNITY DIAGNOSIS
3. HEALTH SERVICES EVALUATION
4. TO KNOW THE INDIVIDUAL RISKS AND CHANCES
5. SYNDROME IDENTIFICATION
6. COMPLETING THE CLINICAL PICTURE
7. SEARCHING FOR CAUSES / RISK FACTORS FOR
   ESTABLISHING CAUSAL RELATIONSHIP

29
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

30
COMMUNITY DIAGNOSIS
SOCIAL ANATOMY
SOCIAL PATHOLOGY
SOCIAL PHYSIOLOGY
QUANTIFICATION
QUALITATIVE ESTIMATION
31
COMMUNITY DIAGNOSIS

1. SOCIAL ANATOMY RACE, AGE AND
   SEX COMPOSITION, SOCIO ECONOMIC STATUS,
   POPULATION AT RISK, RESOURCES AVALAIBLE.
2. SOCIAL PHYSIOLOGY POSITIVE NEGATIVE
   LIFESTYLES, OCCUPATION, HEALTH SERVICES AWARENESS
   AND UILIZATION, NUTRITIONAL POLICES, LABOUR.
3. SOCIAL PATHOLOGY MORBIDITY, MORTALITY,
   DISABILITY, ALCHOLISM, SMOKING, CRIME VOILENCE,
   RISK PRONE BEHAVIOUR.

32
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.

33
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
COMMUNITY HEALTH
OLD DISEASES
34
HEALTH SERVICES EVALUATION

• HEALTH PLANNING FOR
• APPROPRIATE
• COST EFFECTIVE
• COMMUNITY NEED BASED
• JUDICIAL MIX OF PREVENTIVE, PROMOTIVE, CURATIVE,
  REHABILITATIVE AND PUBLIC HEALTH SERVICES

35
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
36
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

37
COMPLETING THE CLINICAL PICTURE OF DISEASE

• IN BREADTH
• 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

38
NATURAL HISTORY OF DISEASE
39
RISK ASSESMENT

• INDIVIDUAL RISK
• GENERAL POPUTLATION RISK
• PROGNOSIS FOR BY PHYSICIAN

40
CYCLE OF EXTENSION
41
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