Measurements of Measurements of Health and Health and

diseasedisease

The simplest and most frequently The simplest and most frequently performed quantitative performed quantitative measurement in epidemiology is a measurement in epidemiology is a count of the number of persons in count of the number of persons in the group who have a particular the group who have a particular disease or a particular disease or a particular characteristics, for example, it characteristics, for example, it may be noted that to people in may be noted that to people in two college dormitories two college dormitories developed infectious hepatitis developed infectious hepatitis type A.10 students in the first one type A.10 students in the first one and 20 students in the second .and 20 students in the second .

ProportionProportion:: For a count to be descriptive For a count to be descriptive

of a group it must be seen in of a group it must be seen in proportion to it; that is must proportion to it; that is must be divided by the total number be divided by the total number in the group. The 10 hepatitis in the group. The 10 hepatitis cases would have quite cases would have quite differences significance for the differences significance for the dormitory housed 20 student dormitory housed 20 student than if it housed only500. than if it housed only500.

In In the first case the proportion the first case the proportion would be 0.5 (50%). In the second would be 0.5 (50%). In the second case the proportion would be case the proportion would be 0.02(2%) The use of denominators 0.02(2%) The use of denominators to convert counts into proportion to convert counts into proportion seems simple to mention. A seems simple to mention. A proportion is one basic way to proportion is one basic way to describe a group. It is important describe a group. It is important to enumerate appropriate to enumerate appropriate denominators in order to describe denominators in order to describe and compare groups in a and compare groups in a meaningful and useful way. meaningful and useful way.

RatioRatio Is numerical expression, Is numerical expression,

which indicates the which indicates the relationship in quantity relationship in quantity between two parts, the between two parts, the ratio of male to female is ratio of male to female is 2:1.2:1.

RateRateA rate is the quantity, A rate is the quantity, amount or degree of amount or degree of something measured something measured in in specific period of specific period of time.time.

Population at riskPopulation at risk Is that part of population that Is that part of population that

is potentially susceptible to is potentially susceptible to the disease studied.the disease studied.

For instance, men should not For instance, men should not be included in calculation of be included in calculation of carcinoma of the cervix. carcinoma of the cervix. Occupational injuries occur Occupational injuries occur only among working people only among working people (workforce).(workforce).

PrevalencePrevalence:: The number of existing cases The number of existing cases

depends on the number of depends on the number of people who develop their illness people who develop their illness in the past and have continued in the past and have continued to be ill at the present time.to be ill at the present time.

Period prevalencePeriod prevalence The The presence of particular presence of particular disease over a longer period.disease over a longer period.

IncidenceIncidence: : Is defined as the Is defined as the number (No.) of number (No.) of new new casescases of disease of disease

Incidence rateIncidence rate: : No. of new cases in the No. of new cases in the population during specific population during specific period/ no of population at period/ no of population at risk of developing the risk of developing the disease at that period . disease at that period . Incidence is the measure of Incidence is the measure of disease developing in a person disease developing in a person who did not have the disease .who did not have the disease .

Factors of`Factors of`Influencing Influencing

prevalence rateprevalence rate: : 1.The number of 1.The number of new new

casescases2.The severity of illness2.The severity of illness3.The duration of illness3.The duration of illness

Period prevalencePeriod prevalence:: The prevalence of a The prevalence of a

particular disease in a particular disease in a longer period such as one longer period such as one month , six months , one month , six months , one year or even more (life year or even more (life time prevalence)time prevalence)

Point prevalencePoint prevalence: : Is used to know how much Is used to know how much

of a particular disease is of a particular disease is present in a population at present in a population at a particular point in time , a particular point in time , example Dec. , 31, 2010.example Dec. , 31, 2010.

Incidence

Cure Death

Prevalence

Relationship between incidence and prevalence

Prevalence = Incidence × average duration of dis.

2009

31-Dec.

2010

31-Dec.

IncidenceIncidence is a measure of a is a measure of a disease developed in a person disease developed in a person who did not have the diease ( who did not have the diease ( transition from non disease transition from non disease to disease status , any person to disease status , any person in the Y ( denominator )has in the Y ( denominator )has the potential to become part the potential to become part of the group that is counted of the group that is counted in the numerator (X) in the numerator (X)

The important point in The important point in incidence is that whatever incidence is that whatever time period is used in the time period is used in the calculation must be calculation must be clearly specified , and all clearly specified , and all individuals included in the individuals included in the calculation must have calculation must have been observed ( at risk ) been observed ( at risk ) for the entire period .for the entire period .

tools used to evaluate the health tools used to evaluate the health status of the community .status of the community .

By vital statistics we refer to By vital statistics we refer to data collected from ongoing data collected from ongoing recording ,registration of all recording ,registration of all vital events ( birth, vital events ( birth, deaths ,fetal deaths ,marriages deaths ,fetal deaths ,marriages and divorces .and divorces .

The physician is responsible for The physician is responsible for filling the certificates of death , filling the certificates of death , birth and fetal death birth and fetal death

Vital statisticsVital statistics::

Measures of Measures of fertilityfertility: :

Fertility refers to actual Fertility refers to actual bearing of children .bearing of children .

Crude Birth Rate Crude Birth Rate (CBR)(CBR)

K) populationyear mid ( Average)year a (during births live of .No

Crude Birth Rate Crude Birth Rate (CBR)(CBR) : :Is the No. of live Is the No. of live births per 1000 population births per 1000 population of certain locality and of certain locality and year .year .

1000localityyear mid

year andlocality certain of births live of .No

General fertility General fertility raterate

45yrs)- 15 ( agebearin child of women of No. Total

)year a (during births live of No.

Age specific Age specific fertility ratefertility rate

age specified theof women of No. Totalagecertain a of women thebirth to live of No.

Total Fertility Total Fertility RateRate::

The average No. of The average No. of children that would be children that would be born to women born to women surviving until surviving until menopause.menopause.

Birth rate is generally high in Birth rate is generally high in developing countries including developing countries including Iraq , due to :Iraq , due to :

1- high fertility rates due social 1- high fertility rates due social and traditional motives .and traditional motives .

2- poor family planning facilities 2- poor family planning facilities 33–– factors related to marriage factors related to marriage

( the youngest age of marriage ( the youngest age of marriage is associated with long is associated with long childbearing period .childbearing period .

MORTALITY RATESMORTALITY RATES

A mortality rate is a measure A mortality rate is a measure of the frequency of of the frequency of occurrence of death in a occurrence of death in a defined population during a defined population during a specified interval .specified interval .

Crude Death Rate ( CDR)Crude Death Rate ( CDR) ==

year same theof (MYP) populationYear Mjd

causes and ages allfor deaths of No. Total

Age specific death rateAge specific death rate : : Mortality at specific age Mortality at specific age group .group .

Infant Mortality Infant Mortality RateRate

The infant is the baby in the The infant is the baby in the first year of life (the baby first year of life (the baby below one year of agebelow one year of age((

Infant Mortality Rate : It is Infant Mortality Rate : It is the number of deaths of the number of deaths of infants (below one year) per infants (below one year) per 1000 live births in a certain 1000 live births in a certain locality (or country) and year locality (or country) and year

Infant Mortality Rate Infant Mortality Rate IMRIMR

Κyear &locality same thebirths live of .No Totalyear &locality certain ain age ofyear 1under Deaths of .No

What is the infant What is the infant mortality rate in Iraq mortality rate in Iraq during the year 2013 ????during the year 2013 ????

Neonatal Mortality Rate Neonatal Mortality Rate NMRNMR

Is the number of deaths Is the number of deaths of infants during their of infants during their first month (or 4 weeks) first month (or 4 weeks) per 1000 live births in a per 1000 live births in a certain locality and year certain locality and year

Post Post –– neonatal Mortality neonatal Mortality RateRate

Is the number of deaths Is the number of deaths of infants from one of infants from one month to one year of month to one year of age per 1000 live births age per 1000 live births in a certain locality (or in a certain locality (or country) and year.country) and year.

Children 1-4 years Children 1-4 years MortalityMortality

It is age specific mortality of It is age specific mortality of preschool children and so preschool children and so called preschool child called preschool child mortality . It is the number of mortality . It is the number of death of children aged 1-4 death of children aged 1-4 years per 1000 children of the years per 1000 children of the same age group in a given same age group in a given locality or country and year locality or country and year

Stillbirth RateStillbirth Rate Stillbirth is a viable fetus Stillbirth is a viable fetus

delivered after the 28delivered after the 28thth week of week of pregnancy without showing any pregnancy without showing any sign of life after being completely sign of life after being completely expelled from mother expelled from mother

Stillbirth rate is the number of Stillbirth rate is the number of fetal deaths after the 28fetal deaths after the 28thth week of week of pregnancy per 1000 liveborn in a pregnancy per 1000 liveborn in a locality and year locality and year

Perinatal Mortality RatePerinatal Mortality Rate Perinatal period :is the period around Perinatal period :is the period around

labour fom 28labour fom 28thth week of pregnancy to week of pregnancy to the end of first week after labourthe end of first week after labour

Perinatal Mortality Rate: It is the Perinatal Mortality Rate: It is the number of death occurring in the number of death occurring in the perinatal periodperinatal period , from 28, from 28thth week of week of pregnancy to the end of first week pregnancy to the end of first week after labourafter labour per 1000 liveborn in a per 1000 liveborn in a given locality and yeargiven locality and year

Maternal Mortality Rate Maternal Mortality Rate MMRMMR

Maternal mortalityMaternal mortality means death means death of mother due to causes related of mother due to causes related to pregnancy labour and to pregnancy labour and puerperium .Risk is more with puerperium .Risk is more with abortion and ectopic pregnancy abortion and ectopic pregnancy and during child birth and early and during child birth and early puerperium puerperium

Maternal MortalityMaternal Mortality RateRate :Is the :Is the number of deaths of mothers due number of deaths of mothers due to causes related to pregnancy to causes related to pregnancy labour and puerperium per labour and puerperium per 100000 live born in a given 100000 live born in a given locality and yearlocality and year

Maternal Mortality Rate Maternal Mortality Rate MMRMMR==

000001yeasr andlocality same in the births live Total puerperium andlabour pregnancy to

related causes toduemother ofdeath of No.

Case Fatality Rate (CFR)Case Fatality Rate (CFR) It is the number of deaths of a It is the number of deaths of a

particular disease per 100 cases particular disease per 100 cases in a certain locality and year .in a certain locality and year .

In outbreaks of a disease in a In outbreaks of a disease in a confined community case confined community case fatality rate is the number of fatality rate is the number of deaths per 100 diagnosed cases deaths per 100 diagnosed cases during a definite period of time during a definite period of time (period of outbreak) (period of outbreak)

Case Fatality Rate Case Fatality Rate (CFR)(CFR)==

1000areaor periodcertain ain disease that of cases All

diseasecertain a from deaths All

Cause Specific Mortality Cause Specific Mortality Rate CSMRRate CSMR

It is used for chronic disease for It is used for chronic disease for example pulmonary T.B. where example pulmonary T.B. where accurate number of cases accurate number of cases occurring within the year is not occurring within the year is not available and so case fatality rate available and so case fatality rate can not be obtainedcan not be obtained

1000locality andyear same theMYPofdiseasecertain a from deaths All

Proportionate Mortality Proportionate Mortality Rate PMRRate PMR

Is the percent or proportion of Is the percent or proportion of the number of deaths of a the number of deaths of a particular disease to total particular disease to total death in a certain locality (or death in a certain locality (or community or group of the community or group of the population )and yearpopulation )and year

Exercise No.1Exercise No.1

Total midyear Total midyear populationpopulation

8000080000

No. of live birthsNo. of live births 20002000Population aged Population aged

45 years and 45 years and moremore

2000020000

Reported fetal Reported fetal deathsdeaths

3232

Maternal deathsMaternal deaths11Total deathTotal death648648

Death under 1 Death under 1 yearyear

4242

Death of person Death of person 45+ years45+ years

300300

Death due to heart Death due to heart diseasedisease

9898

Death due to Death due to cancercancer

6060

Death due to Death due to strokestroke

4848

Cases of heart Cases of heart diseasedisease

10001000

Cases of cancerCases of cancer12001200

CalculateCalculate 1.Crude Birth Rate1.Crude Birth Rate 2.Crude Death Rate2.Crude Death Rate .3.Infant Mortality Rate .3.Infant Mortality Rate 4.Maternal Mortality Rate4.Maternal Mortality Rate 5.Age Specific Mortality Rate 45+5.Age Specific Mortality Rate 45+ 6.Proportionate Mortality Rate due to 6.Proportionate Mortality Rate due to

strokestroke 7.Cause Specific Death Rate due to 7.Cause Specific Death Rate due to

cancercancer

Exercise No.2Exercise No.2

Assume that in a population of Assume that in a population of 100000 persons 20 have 100000 persons 20 have disease X in 1 year 18 die disease X in 1 year 18 die from that disease what are from that disease what are the mortality rate of that the mortality rate of that disease? and what is the case disease? and what is the case fatality rate? and what does fatality rate? and what does this means to you ? this means to you ?