VITAL STATISTICS FAJAR AWALIA YULIANTO COMMUNITY 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 yrs 70+yrs 0-24 yrs 70+yrs yrs female male

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 PREVALENCE INCIDENCEPREVALENCE NUMERATORNumber of new cases of diseases during a specified period of time Number of existing cases of disease ar a given point of time DENOMINATORPopulation at risk FOCUSWhether the event is a new case Time of onset of the disease Presence or absence of a disease Time period is arbitrary; rather a “snapshot” in time USESExpresses the risk of becoming ill The main measure of acute diseases or conditions, but also used for chronic diseases More useful for studies of causation Estimates the probability of the population being ill at the period of time being studied Useful 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 10 n Factors determine prevalence:  The severity of illness  The duration of illness  The numberof new cases That’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 10 n 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 10 n

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 10 n 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 per population and the crude death rate for all cancers in Cote d’Ivoire is 70.5 per 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 period Estimated total population of the same age and sex group of the population in the same area during the same period 10 n

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 age Number 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) MALESFEMALES High income countries Japan France Canada USA Middle income countries Chile Argentina Peru Indonesia Low-income countries Cuba Sri Lanka Angola Sierra Leone

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 year Number of live births that occured among the population of the given geographic area during the same year 10 n

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) MalesFemales High income countries Japan Canada France USA Middle income countries Chile Argentina Peru Indonesia Low income countries Cuba Sri Lanka Angola Sierra Leone

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 WomenMen Zimbabwe Russian Fed Egypt China Mexico USA Japan

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