Lecture Series on Biostatistics No. Biostat - 5 Date: 10.08.2008 MEASURES OF MORTALITY Dr. Bijaya Bhusan Nanda, M. Sc (Gold Medalist) Ph. D. (Stat.) Topper Orissa Statistics & Economics Services, 1988 firstname.lastname@example.org
CONTENTS Introduction Determinants of Mortality Uses of Mortality data Sources of Mortality data Measures of Mortality Life Table
LEARNING OBJECTIVE They will be able to compute different indices of mortality. They will be able to spell out general determinants of mortality. They will be able to spell out usefulness of mortality indicators.
INTRODUCTIONDeath: “the permanent disappearance of all evidences of life at any time after birth” (WHO).• Mortality: • A demographic event – Average risk of dying of a person in the group during a time span. • This is one of the three determinants of population change i.e. fertility, mortality and migration.• Factors of mortality patterns: • Endogenetics (biological): • Exogenetic(environmental):
DETERMINANTS OF MORTALITY Vary over Space and TimeClassified in to three categories:Demographic structure- Age, Sex Composition etc.Social advancement- Age at marriage, Adequacy of medical facilities, General condition of nutrition, Housing and Sanitation, Literacy, Religion, Caste and Community beliefs etc.Economic development- Occupation, Standard of living/ per capita income , Type of economy etc.
USES OF MORTALITY RATE Useful for projecting the future size of the population Identify population groups that are at high risk and in need of health service Indicatives of quality of life and expectation of life at birth. Useful guides to planners Helpful to insurance companies
SOURCES OF MORTALITY DATA There are two sources:I. Direct source Registration of vital events Sample Registration Surveys National Family Health SurveysI. Indirect source Age data of two consecutive censuses may be used to estimates death rates Demographic year book: U.N. Publication World Health Organization (WHO) also provides data
MEASURES OF MORTALITY It is the quantitative and statistical devices to label the risk of mortality to which a population is exposed over a period of time. Different measures of mortality:- Crude death rate: Crude death rate (d) =( D/P)*1000 D= No. of deaths in a population during a given calendar year P= average number of persons living in the population during the year
Merits requires minimum data on mortality Easy to interpret Demerits Since the risk of death is not uniform for different segments of population (age, sex etc.) CDR is a crude measure and cant be used directly for comparing the levels of mortality in two or more countries.
Age Specific Death Rates(ASDR) DxAge specific death rate (ASDR) =nMx= n × 1000 n PxnDx = No. of death between x and x+n in the yr.nPx = No. of persons aged between x and x+n inthe middle of yr.Note: Line graph of ASDR at y-axis and age atx-axis it shows J-shape pattern for developedcountries and U-shape pattern for developingcountries because in developing countriesmortality rates are comparatively higher atyounger ages.
Infant Mortality Rate (IMR)No. of infants dying under one year of age in ayear per thousand live birth in a givengeographical region. D0 IMR= × 1000 BD0 : No. of infants who died before celebratingtheir first birthday.B : Total No. live births occurring in that yearand geographical region.
Child Mortality Rate (CMR)Defined as the total number of deaths ofchildren aged 1 to 4 yrs. per 1000 populationof the same age in a given year andgeographical region. No. of deaths of children aged 1to 4 yr in given yr and regionCDR = × 1000 tot. population aged 1 to 4 in the given yr and a given region
Neonatal Mortality Rate (NMR): No. of infants dying within the first 4 weeks or up to 28 days of life per 1000 live birth in a year and geographical region. Deaths of infants up to 4 weeks NMR = × 1000 No. of live birthsEarly Neonatal Mortality Rate (NMR): No. of infant deaths during the first seven days of life per 1000 live births in a year and geographical region.ENMR = Deaths of infants in the first week of life × 1000 No. of live births
Perinatal Mortality Rate (PMR)No. of still births/ late foetal deaths (after 28weeks of gestation) plus deaths within firstweek of life in a year and geographical regionfor 1000 births (live and still) in a year andregion. Foetal deaths after 28weeks of gestation + deaths of newborns within 7daysPMR= × 1000 No. of live births during the same year
Post Neonatal Mortality Rate (PNMR) Number of infants deaths after 28 days toless than 1yr (between 4 weeks to 52 weeks)of age per 1000 live births in a given year. No. of deaths of newborns between 4weeks or less than 1yr old in a yearPNMR= × 1000 No. of live births during the same yr
Maternal Mortality Ratio (MMR) No. of deaths of women while pregnant or within 42 days of termination of pregnancy from any cause related to pregnancy/ childbearing and child birth per 100,000 live births in a given year. Deaths of pregnant women and women after termination of pregnancy within 6 weeks from any cause related to pregnancyMMR= × 100000 No. of live births during the same year
Maternal Mortality Rate (MMRT)Number of maternal deaths while pregnantor within 42 days of termination ofpregnancy from any cause related topregnancy/ childbearing and childbirth per100,000 women in reproductive ages 15-49. No. of maternal deaths of women in age 15-49MMRT = × 1000 No. of women in age 15-49 in a given yr
Foetal Death: Deaths prior to the complete expulsion or extraction from its mother of a product of conception at any time of pregnancy. Still Birth Death of foetus after completing 28 weeks and till the time of birth. Incidence Rate Number of NEW cases of specified diseases occurring in a defined population during a specified period of time.
(Continued…………) No. of new cases of specified disease during a given periodIncidence rate = × 1000 Population at risk Prevalence Rate Number of all current cases (old and new) of a disease at one point in time in relation to defined population. No. of new and old cases of specified disease existing at a given point in time Prevalence rate = × 1000 Estimated population at the same point in time
s th ks of gestation completed Toddler Post Late Early Still Birth Death Neonatal Neonatal Neonatal Death Death Death Neonatal Death Perinatal Death Infant DeathTime Reference for Mortality in Childhood and Infancy
Limitations of Measures of Mortality The risk in a population may vary largely with various socio-economic and biological traits. The lack of reliable and requisite data presents serious problem sometimes of considerable magnitude.
Exercise: Calculate the crude and Age specific death rates of the population from the following data Age-group Population Deaths (Years) Under 10 20,000 600 10-20 12,000 240 20-40 50,000 1,250 40-60 30,000 1,050 Above 60 10,000 500
Expectation of Life The curate Expectation of life, (ex) gives the average number of completed years of life lived by the cohort l0 after age x by each of lx persons attaining that age. The complete expectation of life, denoted as exo, measures the average number of years a person of given age can be expected to live under the prevailing mortality conditions. It gives the number of years of life entirely completed and includes the fraction of the year survived in the year in which death occur, which on the average can be taken to be ½ years. exo = ex +1/2
REFERENCE An Introduction to the Study of Population, Bhaskar D. Mishra Techniques of demographic Analysis, K. B Pathak, F. Ram Fundamentals of Applied Statistics, S.C Gupta and V. K Kapoor.