8/12/2010 descriptive epidemiology nursing 1 comunicación y gerencia

8/12/2010 Descriptive Epidemiology Nursing1

Comunicación y Gerencia

8/12/2010Descriptive Epidemiology Nursing2

Descriptive epidemiologyDescriptive epidemiology

Associate ProfessorAssociate ProfessorFamily & Community Medicine DepartmentFamily & Community Medicine Department

King Saud UniversityKing Saud University


Learning Objectives:Learning Objectives:

By the end of this lecture students will be able to:By the end of this lecture students will be able to:

• Describe Person, Place and Time characteristics of Describe Person, Place and Time characteristics of

disease occurrence.disease occurrence.

Identify the uses of descriptive epidemiologyIdentify the uses of descriptive epidemiology


Descriptive epidemiologyDescriptive epidemiology describes the describes the

distributiondistribution of health-related events by time, of health-related events by time,

place, and personal characteristics in order to place, and personal characteristics in order to

answer: answer:

when (time), when (time),

where (place), where (place),

who (person).who (person).


I- Time Variation of disease occurrenceI- Time Variation of disease occurrence• Annual occurrence, seasonal occurrence, and Annual occurrence, seasonal occurrence, and

daily or even hourly occurrence of disease may daily or even hourly occurrence of disease may occur.occur.

• Knowing time trend of a disease will help health Knowing time trend of a disease will help health professionals establish professionals establish controlcontrol measures. measures.

Time trend include:Time trend include:Secular trend (long-term)Secular trend (long-term)Periodic (cyclic variationPeriodic (cyclic variation)) Rapid fluctuation (short time)Rapid fluctuation (short time)


Secular (long-term) trends:Secular (long-term) trends:

Graphing the annual cases or rate of a disease over a Graphing the annual cases or rate of a disease over a

period of period of yearsyears (Decades or centuries) shows long- (Decades or centuries) shows long-

term or secular trends in the occurrence of the term or secular trends in the occurrence of the

disease.disease.

We commonly We commonly useuse these trends to these trends to suggestsuggest or or predictpredict

the future incidence of a disease. the future incidence of a disease.


Secular (Long-term trend) is influenced by

population features e.g.

– Change of degree of susceptibility e.g. by

immunization

– Socioeconomic

– Environmental sanitation and

– Nutritional status of a population.

8/12/2010Descriptive Epidemiology Nursing8

Death rate for Tuberculosis, 1860-1960, United States, Source: US Bureau of the Census, Historical Statistics of the United States; Colonial Times to 1970 (Washington, D.C: Government Printing Office, 1975), Part 1 pp58,63. Note: Data between 1860 and 1900 for Massachusetts only.


Changing TB mortality Changing TB mortality

In the last century, In the last century, declinedecline in TB mortality was due to: in TB mortality was due to:

– better housing, ventilationbetter housing, ventilation

– improved nutritionimproved nutrition

– medical care (streptomycin reduced deaths in UK by medical care (streptomycin reduced deaths in UK by

51% 1948-1971). 51% 1948-1971).


Recently, TB rates are increasing. why?Recently, TB rates are increasing. why?

EnvironmentalEnvironmental: (poor nutrition, housing, hygiene,

sociopolitical; wars).

HostHost changes: increased susceptibility (e.g.

HIV/AIDS infection), travel, migration,..

AgentAgent changes: Development of drug resistant

strains of TB.


Periodic (cyclic variation)Periodic (cyclic variation)

Where disease occurrence for a period then

increase again in cycliccyclic pattern


SeasonalitySeasonality:

By graphing the occurrence of a disease by week or By graphing the occurrence of a disease by week or

month over the course of a month over the course of a yearyear or more we can show or more we can show

its seasonal patternits seasonal pattern

Example:Example:

Cases of Cases of influenzainfluenza increases in winter. increases in winter.

Food poisoning and Food poisoning and diarrheadiarrhea increase in summer. increase in summer.


Rapid fluctuation Rapid fluctuation ((short time)

Usually occur in the form of point source Usually occur in the form of point source

epidemicsepidemics that appear abruptly and that appear abruptly and

ends abruptly either natural or due to ends abruptly either natural or due to

intervention.intervention.

e.g. food poisoning e.g. food poisoning


II- Place characteristicsII- Place characteristics

Disease may vary by: Disease may vary by:

• place of residence, place of residence,

• birth place, birth place,

• place of employment,place of employment,

• School district, School district,

• hospital unit, etc.hospital unit, etc.


Place characteristicsPlace characteristics

Analyzing data by place can give an idea of Analyzing data by place can give an idea of

where the where the agentagent that that causescauses a disease lives and a disease lives and

multiplies, multiplies,

whatwhat may carry or transmit it, and may carry or transmit it, and

howhow it spreads. it spreads.

Use Use spot mapspot map to locate the possible to locate the possible sourcesource or or riskrisk

factors.factors.


GeographyGeography

The location of certain place determine its

climatic conditions e.g. temperature,

humidity, wind,… which favour certain

agents and vectors.

e.g. malaria, Yellow fever,..

Disease variation by Place may be due to:Disease variation by Place may be due to:

8/12/2010

19

Descriptive Epidemiology Nursing


GeologyGeology

The structure of The structure of soilsoil affects disease affects disease

occurrence e.g. occurrence e.g.

Hardness of water ----- CVDHardness of water ----- CVD

Radioactive materials ------ leukemiaRadioactive materials ------ leukemia


Chemical and physical environmentChemical and physical environment

Iodine deficiency in the soil (oasis) ---goiterIodine deficiency in the soil (oasis) ---goiter

Sulpher dioxideSulpher dioxide ------- chronic bronchitis------- chronic bronchitis


Environmental sanitationEnvironmental sanitation

Filth diseases in poor sanitation Filth diseases in poor sanitation Good sanitation decrease diarrhoeal Good sanitation decrease diarrhoeal

diseasesdiseases


Availability of Health ServicesAvailability of Health Services

Vaccination ---prevent infectious diseasesVaccination ---prevent infectious diseases

Health Education ---- healthy behaviourHealth Education ---- healthy behaviour

Detection and treatment of infectious Detection and treatment of infectious

diseases ------- limit spread.diseases ------- limit spread.


III- Person characteristicsIII- Person characteristics::

In descriptive epidemiology, we also organize or In descriptive epidemiology, we also organize or

analyze data by “person” characteristics analyze data by “person” characteristics

such as:such as:

age, sex, race, religion, marital status, age, sex, race, religion, marital status,

socioeconomic status,…..socioeconomic status,…..


Age:Age:

Age is probably the single most important “person” Age is probably the single most important “person”

attribute, because almost every health-related event attribute, because almost every health-related event

or state varies with age.or state varies with age.

Age affects:Age affects:

• Type of disease:Type of disease: e.g. e.g.

Neonates ----- congenital anomalies and birth traumaNeonates ----- congenital anomalies and birth trauma

Elderly ------ Degenerative diseases, CVDElderly ------ Degenerative diseases, CVD


Severity of disease:Severity of disease:

– Whooping cough is severe under one yearWhooping cough is severe under one year

– Pneumonia is fatal in early 2 monthsPneumonia is fatal in early 2 months

– Fracture is severe in old ageFracture is severe in old age


Clinical form of disease:Clinical form of disease:

Thyroxine deficiency ---- cretinism in youngThyroxine deficiency ---- cretinism in young

----Myxodema in adults----Myxodema in adults

T.B. ------T.B. ------ Miliary in childrenMiliary in children----- Pulmonary in adults----- Pulmonary in adults

Explanation of disease variation by age may be explained by Explanation of disease variation by age may be explained by

exposure to risk factors or exposure to risk factors or

degree of immunity or susceptibility degree of immunity or susceptibility

response to a causative agent..


Sex:Sex:

Some diseases are sex-linked due to:Some diseases are sex-linked due to:

• anatomic differences e.g. cancer cervix , cancer anatomic differences e.g. cancer cervix , cancer

prostate or,prostate or,

• genetic differences between the sexes e.g. genetic differences between the sexes e.g.

Haemophilia.Haemophilia.

• Other diseases are related to occupations and Other diseases are related to occupations and

environmental exposure which differ in both environmental exposure which differ in both

sexes. e.g. accidents and lung diseasessexes. e.g. accidents and lung diseases


Ethnic and racial groups:Ethnic and racial groups:

Ethnic group: any group of people who have lived Ethnic group: any group of people who have lived

together long enough to acquire common together long enough to acquire common

characteristics, either biologically or socially.characteristics, either biologically or socially.

Some races are susceptible to specific diseases e.g. Some races are susceptible to specific diseases e.g.

sickle cell anaemia in Negros due to genetic sickle cell anaemia in Negros due to genetic

predisposition predisposition

Some races got immunity due to long exposureSome races got immunity due to long exposure


Familial tendencyFamilial tendency Clustering of some diseases within

certain families may be due to:

– Genetic factors, or

– common exposure to the same dietetic,

social, psychological and environmental

influences.


Religion Religion

Religion usually determine the behaviour of

its followers

Prohibition of alcohol ----- liver disease

Male circumcision------ cancer cervix


Study of disease frequency with marital Study of disease frequency with marital status indicates that:status indicates that:– Mental illnesses are more likely to affect Mental illnesses are more likely to affect

single individuals.single individuals.– Breast cancer affects more females who Breast cancer affects more females who

remain single or marry late, remain single or marry late, – Cancer cervix is more common among Cancer cervix is more common among

early married females.early married females.

Marital StatusMarital Status


Death rates are lower for married than for single. This may be due to:

Persons who live dangerously tend to live single.

Persons in poor health tend to remain single. There are differences in habits and way of life

of single and married people; feeding outdoor,…

Marital StatusMarital Status


Thank YouWebsite http://faculty.ksu.edu.sa/73234/default.aspx

[email protected]

8/12/2010 descriptive epidemiology nursing 1 comunicación y gerencia

Documents

hourly occurrence of

time trend

seasonal occurrence

cyclic pattern slide

comunicacin y gerencia

secular trends

secular longterm trends

changing tb mortality