DR. SHAMAZ MOHAMED

Health and diseaseWhat do mean by disease? dis/ease……that is not at ease.• “Any deviation from normal functioning or a

state of complete physical or mental well being”.• So what is health?• Health has been seen by different groups in

different prospective.• As the world changes the concepts of health also

evolved based on the new patterns of thought.

Medicine in antiquity

Dawn of Scientific medicine1500 AD was marked by various revolutions

in the field of politics, industry, religious,, medical, etc.

Thus with the advancing of revolutions, the civilizations, the medicine also evolved and thus the standard of living among people.

Sanitary awakeningRise of public health- 1840Germ theory of disease-1860- louis Pasteur-

presence of bacteria in air.Birth of preventive medicine

Modern medicine

Changing concepts of health

So what is health how do we define it ?It is one of the most difficult word to define

although we are confident of its meaning.WHO definition –

“ health is a state of complete physical, mental,

and social wellbeing and not merely absence of disease or

infirmity”

OPERATIONAL DEFINITION OF HEALTH

BROAD SENSE – a condition or quality of the human organism expressing the adequate functioning of the organism in given conditions, genetic or environmental

NARROW SENSE- a) no obvious evidence of disease, & that a person is functioning normally

A kind of equilibrium or homeostasis- organs of body are functioning adequately within themselves & in relation to one another.

NEW PHILOSOPHY OF HEALTH 1. Health is a fundamental human right 2. Health is the essence of productive life, & not

the result of ever increasing expenditure on medical care

3. Health is intersectoral 4. health is an integral part of development 5. Health is central to the concept of Quality of life 6. Health involves individual, state &

international responsibility 7. health & its maintanence is a social

responsibility 8. health is world wide social goal

Dimensions of health

Health is multi dimensional.

Each dimensions interact with each other but also has its own nature, descriptive purposes and can be treated separately

Health

Public health

Public + Health

Winslow‘s definition 1920 – “the art and science of preventing disease,

prolonging life and promoting physical and mental efficiency, through organized community efforts…….

Changing concepts of public health

Disease control phaseDuring the 19th century, disease control

phase was a matter aimed at the control of man’s physical environment.

E.g. : water supply and sewage disposalIt was largely a matter of sanitary legislation

and reforms aimed at control of mans physical environment

Health promotional phaseAt the beginning of 20th century a new concept

of health promotion began to take shape.It was initiated as personal health services such

as mother and child health services, school health services, industrial health services etc.

The 2 great movements started were

1.Basic health services through primary health centres and sub centre.

2.Community development programme through participation of whole community.

Social engineering phasesIn this phase the public health moved into more of

preventive and rehabilitative aspects of disease.With the advances of preventive medicine the

disease pattern began change from acute to chronic state. The chronic disease could not be tackled by traditional methods like isolation, immunization, nor could be explained by germ theory.

A new factor called risk factors thus came into existence. This led to probe into social factors as determinants of health.

Health for all phaseInequalities in health

1981- WHO-a target was pledged “ health for all by the year 2000”, -that is attainment for all of a level of

health that will permit all people to lead a socially and economically productive life.

HEALTH

Spectrum of health Positive health Better health Freedom from sickness Unrecognized sickness Mild sickness Severe sickness Death

Health Indicators

A question that is often asked is “how healthy is a given population”? so to measure the health status and to quantify the health

problems there is a need of health information on the health of the population, so that we can know the disease trends and compare with other populations.

The health information system is composed of several subsystems, comprehensive health information system requires the main tool that is indicators (health).

the sources of information i.e. indicators are collected by method of census, registration of vital events, notification of diseases, hospital records, surveys etc.

Definition: so as the name suggests “they are only an indication of given situation or

reflection of that situation”.

Health index is generally considered to be amalgamation of many health indicators and mostly used to measure or state the condition of health.

Many indicators are essential for the measurement of health as it is multidimensional in nature.

Characteristics of Indicators

Reliability: They should actually measure what they are supposed to measure

Validity: The answers should be the same if measured by different people in similar circumstances

Sensitivity: They should be sensitive to even small changes in the situation concerned

Specificity: They should reflect changes only in the situation concerned

Feasibility: They should have the ability to obtain the data needed

Relevant: They should contribute to the understanding of the phenomenon of interest

Types of indicators1. Mortality indicators2. Morbidity indicators3. Disability rates4. Nutritional state indicators5. Health care delivery indicators6. Utilization rates 7. Indicators of social&mental health8. Environmental indicators9. Socio-economic indicators10. Health policy indicators11. Indicators of quality of life12. Other indicators

Mortality indicatorsDefinition: “the no deaths due to a disease in

a general population or community”.So how do we collect the information on

death?Death certificate

Mortality rates &ratios1. Crude death rate: “ Defined as no of deaths per1000

estimated mid year in one year, in a given population”

formula: Number of deaths during the year x 1000 Mid year populationThe crude death rate summarizes the population

composition &age specific death rate.

2.Expectation of life: life expectancy at birth is “the average no of years that will be lived by those born alive into a population if the current age specific mortality rates persists”.

One of the goals of HFA/2000 was to attain life expectancy of 64yrs at birth.

India in2001 attained males-64.0 yrs females-62.80 yrs

3. Infant mortality rate: “the ratio of deaths under 1year of age in a

given year to the total no of births in the same year” usually expressed as a rate per 1000 live births

It is also a sensitive indicator of prenatal care.

3. Child mortality rate: it is indicator of overall health status In early stage of childhood(1-4years) mortality rate.

it excludes infant mortality rates.4. Under -5 mortality rate: it is useful to know

what portion of total population deaths are due to particular age or disease.

High rates reflect short life expectancy rate.

5. Maternal mortality rate:6. Disease specific mortality:

Uses of mortality data:statistics on causes of death important and

widely used for no of purposes1. Indicate priorities for health action&allocation of

resources.2. In designing intervention programmes.3. In assessment& monitoring of public health

programmes.

Limitations:1. In complete reporting of deaths2. Lack of accuracy3. Lack of uniformity4. Choosing a single cause of death5. Ever changing of coding systems

Morbidity indicators

Definition: “any departure, subjective or objective from a state of physiological wellbeing”.

According to WHO expert committee on health statistics in 6th report measured morbidity in 3 units

1. Persons who were ill2. Periods of illness3. The duration of illness these aspects are measured by

morbidity rates i.e. frequency,duration,severity

Types or morbidity indicators1. Incidence and prevalence2. Attendance rates at the out patient dept3. Admission and discharge rates4. Duration of stay in hospital5. Spells of sickness or absence from school or

work

Incidence Definition: “the no of new cases occurring in a defined

population during a specified period of time”. Formula:

no of new cases of specific disease during a given time period x 1000

population at risk during that period

Incidence measures rate at which new diseases are occurring in a population and it is not influenced by the duration of disease

The use is generally restricted to acute conditions It can also measure new spells or episodes of diseases

occurring in period of time

Uses:1. To control diseases2. Study of diseases3. Efficacy of preventive and therapeutic measures

PrevalenceThe term “disease prevalence” refers

specifically to all current cases(old&new) existing at a given point time or a period of time in a given population.

Types:a) Point prevalenceb) Period prevalence

Point prevalence It is the no of all current cases of a disease at a point in a

given population. The “point” here may for all practical purposes consists of a

day, several days or even weeks depending upon the time it takes to examine the population

Formula: no of all current cases of a specified disease existing

at a given point of time x1000 Estimated population at the same point of time

Point prevalence can be made specific for age,sex,and other revalent attributes

Period prevalence It is less commonly used it measures the frequency of all

current cases existing in a defined period of time, e.g.: (annual prevalence) expressed in a defined population.

It includes cases arising before but extending into or through the year as well as those cases arising during the year

Formula: No of existing cases of a specified disease during a period of

time x 100 Estimated mid interval population at risk

Uses:1. Prevalence helps to estimate the magnitude of

health/disease problems in the community and identify potential high risk population.

2. Prevalence rates are especially useful for administrative and planning purposes e.g. hospital beds, manpower needs etc.

Relationship betweenprevalence&incidence

Prevalence depends on 2 factors the incidence and duration of illness.

Given the assumption that the population is stable and incidence&duration are unchanging, the relationship between incidence & prevalence can be expressed as

P = I x De.g. I =10 cases/1000 population/year D = 5 years P = 10x5=50 per1000 population

Conversely it is possible to derive I and D as follows P = I x D I = P / D D = P / I longer the duration of the disease the greater is its prevalence e.g. tuberculosis

Disability rates Since death rates have not changed markedly in recent

years despite massive health expenditure, disability rates have come into use to supplement mortality& morbidity indicators. The disability rates are based on the premise or notion that health implies a full range of daily activities.

So what do we mean by disability? According to WHO- “any restriction or lack of ability to perform an

activity in the manner or within the range considered normal for a human being”.

Concept of disability:

Disease accident

Impairment loss of foot

Disability cannot walk

Handicap unemployed

The commonly used disability rates fall into two groups:

1. Event type indicators2. Person type indicators Event type indicators:

a) no of days of restricted activitiesb) Bed disability ratesc) work loss days within a specified period

Person type indicators:

1. Limitation of mobility2. Limitation of activity

Sullivan's index: this index (expectation of life free of

disability) is computed by subtracting from the life expectancy the probable duration of bed disability &inability to perform major activities.

HALE( health-adjusted life expectancy): HALE is based on life expectancy at

birth but includes an adjustment for life spent in poor health.

It is most easily understood as the equivalent no of years in full health that a new born can expect to live based on current rates of ill health and mortality.

DALY (disability-adjusted life year): DALY measures the burden of disease in a

defined population and effectiveness of the interventions.

DALY expresses years of life lost to premature death and years lived with disability adjusted for the severity of the disability.

“one DALY is one lost year of healthy life” however their use is limited because

necessary data are not available or do not exist.

Nutritional status indicators It is a positive health indicator. Among many only

3 are considered important as indicators of health status they are:

1. Anthropometric measurements of pre-school children2. Heights of children at school entry3. Prevalence of low birth rate

Anthropometric measurements:

Anthropometric measurements are weight, length, diameters, skin fold thickness, perimeters etc

Height: height in children is a stable measurement of growth as opposed to body weight, where as weight reflects only the present health status of child, height indicates the event in the past also.

Prevalence of low birth rate: birth-weight should be taken preferably within one hour of

birth before post natal weight loss has occurred.Low birth weight means child less than 2.5 kg

significance: high incidence, association with mental retardness,mortality

&morbidity rates, human wastage high cost of special care etc.

In any community mother & children constitute a priority group compromising of 70% of population. In INDIA women of child bearing age(15-44yrs)constitutes 19% & children under 15yrs 40% of population. So they are major consumers of health services of all forms.

Health care delivery indicators The frequently used indicators in this category are:1. Doctor-population ratio2. Doctor- nurse ratio3. Population- bed ratio4. Population per traditional birth attendant

These indicators reflect the equity of distribution of health resources in different parts of the country, and of the provision of health care.

Utilization rates It is expressed as the proportion of people in need of a service who

actually receive it in a given period, usually a year. they give some indication of the care needed by the

population and therefore the health status of the population. examples:

a) Proportion of infants who are fully immunized against 6EPI diseases

b) Bed occupancy ratesc) Average length of stay in hospital. the above list is neither all inclusive nor all exhaustive, it

depends on the services provided.

Indicators of social & mental health

Thee are indirect measures of health.

These includes rates of suicides, homicide, other acts of violence and crimes, road traffic accidents, juvenile deliquency,alcohol and drug abuse, smoking, battered baby etc.

Environmental indicators Environmental indicators reflect the quality of physical and

biological environment in which disease occur and in which the people leave.

They include indicators relating to pollution of air and water, solid wastes, exposure to toxic substances, radiation etc.

In the year 2000 access to safe water in developing countries was around 78% compared to cent percent in developed ones.

Adequate sanitation in developing countries as accessed by around 52% compared to 100%in developed countries.

The stipulated norms for safe water is 40litres/day/capita and one hand pump for every 250 persons.

Socio-economic indicators These are also indirect measures of health They include:1. Rate of population increase2. Per capita GNP3. Level of unemployment4. Dependency ratio5. Literacy rates6. Per capita calorie availability

Indicators of quality of lifeIt is defined as a subjective component of

well being.“a composite measure of physical, mental,

and social wellbeing as perceived by each of individual or by group of individuals”.

quality of life is difficult to define and even more difficult to measure, so various attempts are made to reach a composite index from no of health indicators.

Physical quality of life index:

this is a composite index. It consolidates 3 indicators namely 1. Infant mortality2. Life expectancy at age one3. literacy

For each component the performance of individual countries is placed on a scale of 0 to 100. where 0 represent absolute worst performance and 100 absolute best performance. The composite index is calculated by averaging the 3 indicators giving equal weight to each of them. The resulting PQLI is thus scaled again from 0 to 100.

The ultimate objective is to attain a PQLI of 100

Human development index: Human development index(HDI) is defined as

“a composite index combining indicators representing 3 dimensions

1. Life expectancy at birth2. Knowledge (adult literacy rate &mean year of schooling)3. Income (GDP/capita in purchasing power parity in US) the concept of HDI reflects

achievements in the most basic human capabilities like leading long life ,being knowledgeable and enjoying decent standard of living.

To construct the index ,fixed minimum and maximum values have been fixed for each of these indicators

Life expectancy at birth: 25 yrs and 85 yrs Adult literacy rates : 0% and 100% Combined gross enrolment ratio : 0% and 100% GDP per capita : $100 and $40000 The HDI ranges between 0 to 1.

For any component of HDI indices can be formulated by the formula:

(actual X1 value) - (minimum X1 value) (maximum X1 value) – (minimum X1 value)

The mean of all the 3 indicators are calculated and the final HDI score is got

Health policy indicators The single most political commitment is allocation

of adequate resources. Here the relevant indicators are:

I. Proportion of GNP spent on health servicesII. Proportion of GNP spent on health activities like

water supply& sanitation, nutrition etcIII. Proportion of total health resources devoted to

primary health care.

Other indicatorsA. Social indicators: these are divided into 12

categories by UN statistical office i.e.population,family, family and house hold ,learning and educational services,earning,distribution of income,consumption,and accumulation, social security and welfare services,healthservices &nutrition environment, public order and safety, leisure and culture, and social stratification and mobility.

2. Basic need indicators: these are used by ILO these include calorie consumption, access to water, life expectancy,illetaracy,doctors and nurses per population etc.

3. Health for all indicators(HFA): for monitoring progress towards the

goal of health for all by 2000AD , the WHO has listed the following 4 categories of indicators:

4. Millennium development goal indicators: this millennium goal was adopted by the

UN in the year 2000. It provides an opportunity for concerted action to improve global health. The goals are listed below:

Iceberg of diseaseDisease in a community may be compared with an

iceberg. The floating tip of the iceberg represents what the

physician sees in the community. i.e. .clinical cases.The vast submerged portion of the iceberg

represents hidden mass of disease. i.e. presymptomatic and undiagnosed cases and carriers in the community.

The waterline represents the demarcation between apparent and inapparent disease.

Concept of disease

Concepts

Disease

Prevention

Controls

Disease A condition in which body health is impaired

a departure from a state of health an alteration of the human body interrupting the performance of vital functions.Ecological : a maladjustment of the human

organism to the environmentSociological a social phenomenon occurring in

all societies.

WHOHas defined health not diseaseHas many shades Disease – without ease – is a physiological

/psychological dysfunctionIllness is a subjective state of the person who

feels aware of not being well.Sickness is a state social dysfunction

(sickness role)

Concepts of Causation

Germ theory of disease

Multifactorial Causation Pettenkofer 1819-1901

Modern Day Civilization DisordersNon Communicable DiseasesCHD CVA COPD Mental Illness etc

Web Causation 'Multiple causation' is the canon of

contemporary epidemiology, and its metaphor and model is the 'web of causation.'

Natural history & characteristics

Natural HistoryProgression of diseaseBiological CharacteristicsBiologyReservoirtransmission

Natural History

Appropriate exposure or accumulation ofagent

Incubation period or latency periodHow much time from the start of the

disease process until disease?All diseases have a defined period of time

before symptoms occur.Called subclinical disease.Can be seconds, days, months or years

Biological Characteristics

Infectivity The ability of an agent to cause infection in a

susceptible host. Measured by % of exposed people who become ill.

Pathogenicity Ability of agent to induce disease. Measured by % of infected persons who develop clinically apparent disease.

Virulence Severity of disease after infection occurs

Biological Characteristics

ReservoirThe habitat in which the agent normallylives, grows and multiplies.

Humans, Animals, EnvironmentMode of transmissionHow is the disease spread?

Direct contact, airborne, vehicle-borne,

vector-borne

Pre pathogenesis PhasesPreliminary onset of disease

Disease agent has not entered host

Factors favoring its interaction with host exist in environment “ Man in the midst of disease”

Pathogenesis phase

Entry of the disease in susceptible host

Agent FactorsSubstance, living or non-living or a force,

tangible or intangible the excessive presence or relative lack of which may initiate or perpetuate a disease process.

Biological InfectivityPathogenicity Virulence

HostDemographic

Biological

Social and Economic

Lifestyle

Environment Physical BiologicalPsychosocial

Risk FactorsAn attribute or exposure that is

significantly associated with the development of diseaseObservable or identifiable Additive MultilipicativeCausativeContributoryPredictive Modifiable and immutable

Risk Group Target groups or risk groups

Biological gradient

Physical situation

Socio cultural situation

Concepts of Control Disease Control

Incidence Duration of Disease Effects of infection Financial burdenPrimary or secondary or both

Concepts of ControlDisease Elimination

Termination of all transmission of infection by extermination of the infectious agent absolute process

Disease EradicationInterruption of transmission of disease from

large geographic areas

MonitoringIs the performance and analysis if routine

measurements aimed at detecting changes in the environment or health status of population

Continuous oversight of activities to ensure that they are proceeding according to plan

SurveillanceThe continuous scrutiny of the factors that

determine the occurrence and distribution of diseases and other conditions of ill healthChanging trends in health status Feed back to modify policyPublic health disasters warning

Physician see

what the physician does not see

Iceberg of disease

pre-symptomatic disease

symptomatic disease

Tools of dental public health

Epidemiology Biostatics Social sciences Principles of administration Preventive dentistry

Dentist’s role in public health

1. Proposal to build a new school building 2. Fluoridate the drinking water supply3. Expansion of recreational facilities for

children4. Building a community health centre.5. To discuss community health problems.

Procedural steps in dental public health

1. Survey 2. Analysis programme planning3. Programme operation4. Financing5. Programme appraisal

Difference between PRIVATE PRACTICE & PUBLIC HEALTH

DENTIST

Characteristic Private Practice Public Health Dentistry

1. Target Individual Community or group of individuals

2. Collection of information History & clinical examination Analysis of available health &

morbidity records

3. Special investigation Radiograph, blood test, biopsies,

Exfoliative cytology

Epidemiological surveys

4. Conclusion Diagnosis Situational analysis of health status

and needs and utilization of

services

5. Remedial measures Treatment plan based on diagnosis

patient attitudes and affordability

Action plan based on demands,

available resources and priorities

Characteristic Private Practice Public Health Dentistry

6. Major emphasis Curative Promotive & Preventive

7. Essential requirements for

success

Patient consent and co-operation Community participation

8. Service provider Dentist alone or sometimes with

assistant

Health team professionals, Para

professionals, community

volunteers.

9. Intervention appropriate dental procedure Promotive & Preventive measure at

individual and community level.

10. Supportive disciplines Psychology Sociology, social psychology,

Education, Epidemiology and

Biostatistics.

Characteristic Private Practice Public Health Dentistry

11. Organization & management Not relevant Very relevant

12. Perspective Immediate Long term

13. Evaluation & Results Relief of symptoms and restoration

of function

Formal programme evaluation

14. After care Recall, further sittings Continuing care, self care

15. Funding By the patient Generally by government or local

authorities.