HEALTH FREQUENCY MEASURES Dr. dr. Siswanto, MSc. dr. Holipah

SESSION OBJECTIVES Demonstrate to measure morbidity and mortality Explain the role of morbidity and mortality

SUB TOPIC TOPICMORTALITYDEFINITION MORTALITY FREQUENCE MEASURESMORBIDITY PREVALENCE RATE INCIDENCE RATE

RATE VS RATIO

INCIDENCE RATE the most common way of measuring and comparing the frequency of disease in populations Incidence rate expresses the probability or risk of illness in a population over period of time Since incidence is a measure of risk, when one population has a higher incidence of disease than other, we say that the first population has a higher risk of developing of disease than the second

The formula for calculating an IR 1 The numerator of an incidence rate should reflect new cases of disease which occurred or were diagnosed during the specified period. ( not include cases which occurred or were diagnosed earlier ) 2 The denominator is the population at risk.This mean that person who are included in the denominator should be able to develop the disease 3 The denominator should represent the population from which the cases in the numerator arose

EXAMPLE In 2012, 733 new cases of Tuberculosis were reported among the Malang civilian population. The 2012 mid-year population was estimated to be 246,552. Calculate the 2012 tuberculosis IR What does it mean ? Who are person have probability to get the disease ( Tuberculosis) ? Is the denominator representative for the population ? In 2012, 733 new cases of Tuberculosis were reported among the Malang civilian population. The 2012 mid-year population was estimated to be 246,552. Calculate the 2012 tuberculosis IR What does it mean ? Who are person have probability to get the disease ( Tuberculosis) ? Is the denominator representative for the population ?

PREVALENCE Example : In a survey of patient at a sexually transmitted disease clinic in Malang. 180 of 300 patients is interviewed use of a condom at least during 2 months before the interview. The period prevalence of condom use ( 2 months) = 180 / 300 X 100 = 60 % Example : In a survey of patient at a sexually transmitted disease clinic in Malang. 180 of 300 patients is interviewed use of a condom at least during 2 months before the interview. The period prevalence of condom use ( 2 months) = 180 / 300 X 100 = 60 %

Comparison of prevalence and incidence INCIDENCE Numerator : new cases occurring a given time period The numerator of incidence consists only of persons whose illness began during a specified interval PREVALENCE Numerator : all cases present during a given time period Prevalence includes all persons ill from a specified interval regardless of when the illness began. It include not only new cases but also old cases

The factor that link incidence and prevalence Inc vs Prev Diseases that are short-lived, because they are rapidly cured or are fatal at an early stage, will have a relatively low prevalence compared with their incidence Inc vs Prev Diseases with a low mortality and low cure rate, leaving people with the disabling effect of the disease will have a high prevalence compared with their incidence Inc vs Prev

EXAMPLE Two survey were done of the same community 12 months apart. Of 5000 people surveyed the first time, 25 had antibodies to histoplasmosis. 12 months later, 35 had antibodies, including the original 25. Prev at the second survey = 35/5000 X1000 = 7/1000 Two survey were done of the same community 12 months apart. Of 5000 people surveyed the first time, 25 had antibodies to histoplasmosis. 12 months later, 35 had antibodies, including the original 25. Prev at the second survey = 35/5000 X1000 = 7/1000 Incidence during the 12-month period = ??? CALCULATE Incidence during the 12-month period = ??? CALCULATE

ATTACK RATE ( AR) AR is a variant of an incidence r, applied to a narrowly define pop observed for a limited time, such as during an epidemic. AR is a variant of an incidence r, applied to a narrowly define pop observed for a limited time, such as during an epidemic.

Example Of 75 persons who attended a picnic, 46 subsequently developed gastroenteritis. AR =

SECONDARY ATTACK RATE ( SAR) SAR is a measure of the frequency of new cases of a disease among the contacts of known cases.

Example 7 cases of hepatitis A occurred among 70 children attending a child care center. Each infected child came from a different family. The total number of persons in the 7 families was 32. One incubation period later, 5 family members of the 7 infected children also developed hepatitis A. Calculate AR SAR

AR = 7/70 X 100 = 10 % SAR = 5/25 X 100 = 20 %

MORTALITY RATES NOTICE : Death are usually accurately measured compared with morbidity data.

Disadvantage of a CMR is that it takes no account of the fact that the chance of dying varies according to age, sex, race, socioeconomic class and other factors. It is usually not appropriate to use CMR for comparing different time periods different geographic areas.

EXAMPLE The death rate of people living in a new housing estate with many young families will be very much lower than that in a old housing estate where many retired people chose to live.

INFANT MORTALITY RATE NOTICE : IMR is often used as a measure of overall health status when comparing different countries. ( Why ?? ) ( Indicator health status of a community) East Java ( 2003) IMR = 42 /1000 LB Indonesia ( 2001) IMR = 50/ 1000 LB

Is the IMR rate a proportion ? No, it is a ratio but not a proportion. Relate to the socioeconomic status of an area or country ( Poverty )

Case Fatality Rate NOTICE : CFR is a measure of the severity of a disease, in term deaths.

CRUDE MORTALITY RATE The crude mortality rate is the mortality rate from all causes of death for a population.

CAUSE – SPESIFIC MORTALITY RATE mortality rate from a specified cause for a population The numerator is the number of deaths attributed to a specific cause The denominator remains the size of the population at the midpoint of the time period

AGE-SPECIFIC MORTALITY RATE mortality rate limited to a particular age group The numerator is the number of deaths in that age group the denominator is the number of persons in that age group in the population Some specific types of age-specific mortality rate are neonatal, post neonatal, and infant mortality rates

INFANT MORTALITY RATE one of the most commonly used measures for comparing health services among nations The numerator is the number of deaths among children under 1 year of age reported during a given time period, usually calendar year The denominator is the number of live births reported during the same time period. The infant mortality rate is usually expressed per 1,000 live births

NEONATAL MORTALITY RATE The neonatal period is defined as the period from birth up to but not including 28 days The numerator of the neonatal mortality rate therefore is the number deaths among children under 28 days of age during a given time period The denominator of the neonatal mortality rate, like that of the infant mortality rate, is the number of live births reported during the same time period

POSTNEONATAL MORTALITY RATE The post neonatal period is defined period from 28 days of age up to but not including 1 year of age The numerator of the post neonatal mortality rate therefore is the number of deaths among children from 28 days up to but not including 1 year of age during a given time period The denominator is the number of live births reported during the same time period.

MATERNAL MORTALITY RATE The maternal mortality rate is really a ratio used to measure mortality associated with pregnancy The numerator is the number of death assigned to cause related to pregnancy during a given time period The denominator is the number of live births reported during same time period

SEX-SPECIFIC MORTALITY RATE A sex-specific mortality rate is a mortality rate among either males or females 1 Both numerator and denominator are limited to the one sex 2

RACE-SPECIFIC MORTALITY RATE mortality rate limited to a specified racial group 1 Both numerator and denominator are limited to the specific race 2

COMBINATIONS OF SPECIFIC MORTALITY RATE Mortality rates can be further refined to combinations that are cause-specific, age- specific, sex-specific, and/or race-specific COMBINATION the mortality rate attributed to HIV among 25 – to 44- year-olds in the united states in 1987 was 9,820 deaths among 77.6 million 25- to 44- year-olds, or 12.7 per 100,000. This is a cause- and age-specific mortality rate, because it is limited to one cause (HIV infection) and one age group (25 to 44 years EXAMPLE

The factors that influence mortality morta lity Sex Marriage status Health services status Age Urban or rural Socioeco nomic status Education level

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