MEASURES OF MORTALITY AND OTHER DISEASE IMPACT Flashcards
Refers to the presence of disease in a population.
Morbidity
The state of being susceptible to
Mortality
Frequently Used Measures of Mortality
Crude death rate
Cause-specific death rate
Proportionate mortality
Death-to-case ratio
Neonatal mortality rate
Postneonatal mortality rate
Infant mortality rate
Maternal mortality rate
MORTALITY FREQUENCY MEASURES
MORTALITY RATE
MORTALITY INDICES
Types of MORTALITY RATE
ANNUAL DEATH RATE
SPECIFIC DEATH RATE
CASE FATALITY RATE
PROPORTIONATE MORTALITY
Types of MORTALITY INDICES
YEARS OF POTENTIAL LIFE LOST
DISABILITY ADJUSTED LIFE YEAR
Measure of the number of deaths in a particular population per unit of time
Mortality rate
Serves as a measure of“disease severity”
Mortality rate
Helps us to measure whether treatment for a disease has become more effective over time
Mortality rate
Can serve as surrogates for incidence rates when disease
being studied is a severe and lethal one
Mortality rate
are important to determine the risk of people dying from a health event
Denominators
can decrease mortality rates but also detect more cases now that might
have gone undetected before.
Improved public health programs and campaigns
The estimated total number of deaths in a population of a given sex and/or age, divided by the total number of this population, expressed per 100,000 population, for a given year, in a given country, territory, or geographic area.
Annual death rate (mortality rate) from all causes
Denominator of Annual death rate (mortality rate) from all causes
No. of persons in the population midyear
Specific death rate (annual death rate w/ restriction)
- Age-specific mortality rate
- Disease-specific mortality rate
- Cause-specific mortality rate
- Other demographics:gender,race,etc.
The denominator of Age-specific mortality rate example:
No. of children in the population younger than 10 years of age at midyear
The denominator of Age-specific mortality rate example:
No. of children in the population younger than 10 years of age at midyear
The denominator of Disease-specific mortality rate example:
No. of persons in the population at midyear
The denominator of Cause-specific mortality rate example
No. of children in the population younger than 10 years of age at midyear
Percentage of people who have a certain disease and
who die within a certain time after disease diagnosis
Case-Fatality rate
Use date of diagnosis as a surrogate measure for date of disease onset
Case-Fatality rate
What percentage of people who have a certain disease die within a certain time after their disease was diagnosed?
Case-Fatality rate
The denominator of Case-Fatality rate
No. of individuals with the specified disease
Mortality rate: Numerator
Number of death from all causes or number or death from specific cause of death.
Mortality rate: Denominator
Entire population at risk of dying from the disease.
CASE-FATALITY RATE: Numerator
Restricted to deaths only from specific disease.
Technically not a rate, but a percentage
CASE-FATALITY RATE: Denominator
Limited to those who already have the disease of concern (Measure the severity of disease).
Describes the proportion of deaths in a specified population over a period of time,attributable to different causes
Proportionate mortality (proportion, not a rate)
Each cause is expressed as a percentage of all deaths
Proportionate mortality (proportion, not a rate)
Of all deaths in the United States, what proportion was caused by cardiovascular disease?
Proportionate mortality
T or F | Proportionate mortality ≠ Risk of dying
True
T or F | If there is a change in Proportionate Mortality from certain disease, it may be due to changes of some other disease.
True
Measure of premature mortality,or early death
Years of Potential Life Lost (YPLL)
Recognizes that death occurring in the same person at younger age clearly involves a greater loss of future productive years than death occurring at an older age
Years of Potential Life Lost (YPLL)
Reference range should correspond roughly to the life expectancy of the population being studied
Years of Potential Life Lost (YPLL)
Reference range of USA
75 years of age
Reference range of Philippines
72.12 average years of life
YPLL can assist in three important public health functions: E
YPLL can assist in three important public health functions:
Establishing research and resource priorities
surveillance of temporal trends in premature mortality
and Evaluating the effectiveness of program interventions.
YPLL can assist in three important public health functions:
Establishing research and resource priorities
surveillance of temporal trends in premature mortality
and Evaluating the effectiveness of program interventions.
Another index of disease burden
Disability-Adjusted LifeYear (DALY)
Formula:years of life lost to premature deaths + years
lived with a disability of specified severity and duration
Disability-Adjusted LifeYear (DALY)
1 DALY =
1 lost year of healthy life
In epidemiology,___ is defined as the proportion of persons who are unaffected at the beginning of a study period,but who experience a risk event during the study period.
risk
The risk event may be death, disease, or injury, and the people at risk for the event at the beginning of the study period constitute a _____
cohort
Proportion of persons who are unaffected at the beginning of a study period, but who experiences risk event DURING the study period
Risk
Constitutes the people at risk for the event at the
BEGINNING of the study period
Cohort
Susceptible population:
Susceptible population:
- Risk related to infectious disease
- People without antibody protection
Subsets of the population:
- People who die
- People who are ill
- People who are infected
- People who are exposed
– proportion of clinically ill persons who die
Case fatality ratio
– proportion of infected persons who are clinically ill
Pathogenicity of the organism
- Represents the instantaneous rate of mortality at a certain
age measured on an annualized basis
Force of mortality (FOM)
Number of events that occur in a defined time period divided by the average number of people atrisk (ideally: midyear) for the event during the period under study
Rate
Often used to measure risk
Rate
Number of deaths occurring among the population of a given geographical area during a given year,among a population of 1,000 people
Crude Death Rate
because all ages are represented
“Crude”
When death rate is expressed as describing reality at an
instant in time (probability of death over a short period)
Instantaneous death rate /hazard rate
if event in the numerator occurs more than once during the study
Incidence density –
if event in the numerator occurs more than once during the study
Incidence density
therefore reflects changes in the population by using the midperiod population as an estimate of the average population at risk
Rate
- Number of incident cases over a defined study period
- Divided by the population atrisk atthe midpoint of that study period
Incidence rate
- Actually a proportion and not a rate
- Proportion of persons with a defined disease or condition atthe time they are studied
Prevalence rate
Expressed as per 1,000 /per 10,000 /per 100,000 pop
Incidence Rate
Expressed as a percentage %
Prevalence Rate
- Number of new events per person-time (e.g.per personmonths or per person-years)
- Useful when event of interest can occur in a person more than once during the study period
Incidence density
THREE TYPES OF COMPARISON
* Rates or risks are typically used to make comparisons:
Observed rate (or risk) with a target rate (or risk)
Two different populations atthe same time
Same population at different times
- At the end of study period,observed rates are
compared with set target objectives
Observed rate (or risk) with a target rate (or risk)
- Most common type
- E.g.comparing rates of disease in different countries
Two different populations atthe same time
- Used to study time trends
- Adjustments must be made for changes over time
before coming up with a conclusion
Same population at different times
- Three broad categories of rates:
Crude
Specific
Standardized
- Rates that apply to an entire population without
reference to any individual characteristics
Crude
- Population is divided into homogenous subgroups
- Rates are calculated within these groups
Specific
- Also known as adjusted rates
- Modified crude rates used to control the effects of age
or other characteristics to allow valid comparisons
Standardized
Crude death rates do not take“___” into account
age
investigators should never make comparisons of the risk of death or disease between populations without controlling for ___ (and sometimes for other characteristics as well)
age
ASDR
Age-specific death rate
= sum of the ASDRs in each age
- Crude death rates
STANDARDIZATION OF
DEATH RATES
* Purpose:
- So that investigators can obtain a summary death rate that is free from age bias
- Usually applied to death rates,but may be used to
adjust any type of rate
2 METHODS OF STANDARDIZATION OF
DEATH RATES
- Direct standardization
- Indirect standardization
Most common method to remove biasing/bias effect of different age structures in different populations
Direct Standardization
May also be applied to compare incidence rates of disease or injury as well as death
Direct Standardization
- Used ifASDRs are unavailable in the population
whose crude death rate needs to be adjusted
Indirect Standardization
Used if population to be standardized is small
Indirect Standardization
Uses standard rates and applies them to the known age groups in the population
Indirect Standardization
SMR
- Standardized mortality ratio
Standardized mortality ratio (SMR):
Total number of observed deaths divided by the total
number of expected deaths
- The mortality rate from a specified cause for a population in a certain time period
Cause-specific death rate
- Delivery of a product of conception that shows any signs
of life after complete removal from the mother
Live birth
- Consists of a breath or a cry,any spontaneous movement,
a pulse or a heartbeat,or pulsation of the umbilical cord
Sign of life
- Dead fetus delivered within the first 20 weeks of gestation
Early fetal death (miscarriage)
- Dead fetus delivered between 20-28 weeks of gestation
Intermediate fetal death
- Fetus born dead at 28 weeks of gestation or later
Late fetal death
- Death of a live-born infant before infant’s 1st birthday
Infant death
- Death of a live-born infant before completion of the infant’s 28th day of life
Neonatal death
- Death of an infant after the 28th day of life – 1st bday
Post-neonatal death
- Number of live births divided by the midyear
population per 1,000 (multiplier)
Crude Birth Rate (CBR)
- Used as an overall index of the nation’s health status
Infant Mortality Rate (IMR)
reflects the quality of medical services and
of maternal prenatal behavior (e.g.nutrition,vices, etc.)
Neonatal rate
reflects the quality of the home environment
Post-neonatal mortality rates
Perinatal means
“around the time of birth”
Evaluates the care of pregnant women before and during delivery
Perinatal Mortality Rate
Evaluates the care of mothers and their infants in the immediate
postpartum period
Perinatal Mortality Rate
- Approximation of the perinatal mortality rate in which the
denominator does not include stillbirths
Perinatal mortality ratio
- Useful measure of the progress of a nation in providing
adequate nutrition and medical care for pregnant women
Maternal Mortality Rate
- Death of a woman who is pregnant or who has
recently delivered (6 weeks after childbirth)
Pregnancy-related deaths (puerperal deaths)
