VITAL STATISTICS

FAJAR AWALIA YULIANTOCOMMUNITY RESEARCH PROGRAM1

There is no complete agreement for all epidemiologists for the term used in this field

What will be described afterward is common term that usually used, taken from Last’s Dictionary of Epidemiology

POPULATION AT RISK

An important factor in calculating measures of disease frequency is the correct estimate of the numbers of people under study

a study of carcinoma of the cervix

0-24 yrs

25-69 yrs

70+yrs

0-24 yrs

70+yrs

25-69 yrs

femalemale

POPULATION AT RISK

The people who are susceptible to a given disease are called the population at risk, and can be defined by demographic, geographic or environmental factors

Examples: Occupational injuries occur only among working people, avian influenza occurs only among people handling cattle

INCIDENCE AND PREVALENCE Incidence represents the rate of occurence of

the new cases arising in a given period in a specified population

Prevalence is the frequency of existing cases in a defined population at a given point in time

DIFFERENCES BETWEEN INCIDENCE AND PREVALENCEINCIDENCE PREVALENCENUMERATOR Number of new cases of diseases

during a specified period of timeNumber of existing cases of disease ar a given point of time

DENOMINATOR Population at risk Population at risk

FOCUS Whether the event is a new case Time of onset of the disease

Presence or absence of a diseaseTime period is arbitrary; rather a “snapshot” in time

USES Expresses the risk of becoming illThe main measure of acute diseases or conditions, but also used for chronic diseasesMore useful for studies of causation

Estimates the probability of the population being ill at the period of time being studiedUseful in the study of the burden of chronic diseases and implication for health services

If the incident cases are not resolved, but continue over time, then they become existing (prevalent) cases, prevalence=incidence x duration

If the population at risk undefined, the case numbers still useful to express the magnitude of the health events, e.g during epidemic

Attack rate ~ Incidence, used during the disease outbreak in a narrowly-defined popilation over a short period of time

Attack rate can be calculated as the number of people affected divided by the number exposed

PREVALENCE

P = (Number of people with the disease or condition at a specified time / Number of people in the popilation at risk at the specified time) X 10n

Factors determine prevalence: The severity of illness The duration of illness The numberof new casesThat’s why prevalence study do not usually provide

strong evidence of casuality

INCIDENCE

I = (number of new events in a specified period / Number of persons exposed to risk during this period) X 10n

The numerator strictly tefers only to first events of disease

CUMULATIVE INCIDENCE

Unlike incidence, it measures the denominator only at the beginning of a study

CI = Number of people who get a disease during a specified period / Number of people free of the disease in the population at risk at the beginnig of the period X 10n

CASE FATALITY

Is a measure of the disease severity and is defined as the proportion of cases with a specified disease or condition who die within a specified time

CF = (Number of deaths from diagnosed cases in a given period / Number of diagnosed cases of the disease in the same period) X 100

USING AVAILABLE INFORMATION TO MEASURE HEALTH AND DISEASE

DEATH RATE (CRUDE MORTALITY RATE) CMR = (Number of deaths during a specified

period/ number of persons at risk of dying during the same period) X 10n

The main disadvantage that it does not take into account the fact that the chance of dying varies according to age, sex, race, socioeconomic class and other factors

The following formulation will be diminishing the limitation of CMR

STUDY QUESTION

The crude death rate for all cancers in Japan is 241.7 per 100 000 population and the crude death rate for all cancers in Cote d’Ivoire is 70.5 per 100 000 population. Is the death rate in Japan higher than in Cote d’Ivoire?

AGE SPECIFIC DEATH RATES Can be expressed for specific groups in a

population which are defined by age, race, sec, occipation or geographical location, or for specific causes of death

Total number of deaths occuring in a specific age and sex group f the population in a defined area during a specified periodEstimated total population of the same age and sex group of the population in the same area during the same period

10n

PROPORTIONATE MORTALITY The number of deaths from a given cause per

100 or 1000 total deaths on the same period Proportionate mortality does not express the

risk of members of a population contracting or dying from a disease

INFANT MORTALITY*

It measures the rate of death in children during the first year of life, the denominator being the number of live births in the same year

Number of deaths in a year of children less than 1 year of ageNumber of live births in the same year

1000

CHILD MORTALITY RATE*

Is based on deaths of children aged 1-4 years

Injuries, malnutrition and infectious diseases are common causes of death in this age group

Describes the probability (expressed per 1000 live births) of a child dying before reaching 5 years of age

Child mortality rate in selected countries,2003 (per 1000 live births) MALES FEMALES

High income countriesJapanFrance CanadaUSA

4569

4557

Middle income countriesChileArgentinaPeruIndonesia

10193645

9163237

Low-income countriesCubaSri LankaAngolaSierra Leone

817

276297

613

243270

MATERNAL MORTALITY RATE Refers to the risk of mothers dying from

causes associated with delivering babies, complications of pregnancy or childbirth

Number of maternal deaths from puerperal causes in a given geographic area in a given yearNumber of live births that occured among the population of the given geographic area during the same year

10n

ADULT MORTALITY RATE

Define as the probability of dying between the ages of 15 and 60 years per 1000 population

Adult mortality rates in selected countries, 2004 (per 1000 population) Males Females

High income countriesJapanCanadaFranceUSA

9291

132137

45576081

Middle income countriesChileArgentinaPeruIndonesia

133173184239

6690

134200

Low income countriesCubaSri LankaAngolaSierra Leone

131232591579

85119504497

LIFE EXPECTANCY*

Defined as the average number of years an individual given age is expected to live if current mortality rate continue

Life expectancy atbirth for men and women in selected countries Women MenZimbabweRussian FedEgyptChinaMexicoUSAJapan

34727074778086

37596670727579

ALHAMDULILLAH

Wish every science become virtue, and every mistake become the lesson