Module 3 Flashcards
Annual Mortality Rate
Describes the number of deaths overall per unit of people in a specified population and time frame
Ex: There were 840 deaths per 100,00 in California in 2021
For the rate to make sense, anyone represented by the denominator much have the potential to enter the group represented by the numerator
Total number of deaths from all cause in 1 year/number of persons in the population at midyear X 100,000
Cause-specific mortality rate
Describes the number of deaths dues to a specific cause per unit of people in a specific population and time frame
Example: There were 9 deaths due to firearm injuries per 100,000 in CA in 2021
number of deaths from a specific cause in 1 year/number of persons in the population at mid-year X1000
We can also place a restriction on a rate by specifying a diagnosis, and thus limit the rate to deads form a certain disease.
Proportionate Mortality
The proportion of all deaths in a specified population and time frame that were due to a particular cause
Ex: 1% of all deaths in CA in 2021 were due to firearm injuries
Number of deaths from a specific disease in a specified population and time period/total deaths in the specified population and time period X100
Case-Fatality
The proportion of people with a health condition that die in a specified population and time frame.
Ex: 40% of people with Ebola died in West Africa in March 2024
Number of people dying during a specific time period after disease onset or diagnosis/number of people with the specified disease X 100
Case fatality describes what percentage of people who have a certain disease die within a certain time after their disease was diagnosed.
Case fatality is a measure of the severity or fatality of the disease.
This is actually a proportion and is mistakenly reported as a rate
Standardized Mortality Ratio
(SMR): reflects the ration of the total number of deaths actually observed to the total number of deaths expected, if the population of interest had had the mortality experience of the known population
Ex. Individuals in CA were .5 times likely to die from firearms than the rest of the United States in 2021.
Observed number of deaths per year/expected number of deaths per year
The SMR is calculated using indirect age adjustment and reflects the ratio of the total number of deaths actually observed to the total number of deaths expected if the population of interest had the mortality experience of the known population.
DALY - Disability Adjusted Life Year
The number of years of life lost to premature death and years lived with a disability of specified severity and duration
How does mortality assist in the study of disease occurrence?
Expressing morality in quantitative terms can pinpoint differences in the risk of dying from a disease between people in different populations.
How does mortality help to measure disease severity?
It can help us determine whether the treatments for a disease have become more effective over time.
How does mortality help in identifying new cases of a disease
Mortality rates can serve as a surrogate for incidence rates when the disease is a severe and lethal one
Years of Potential Life Lost (YPLL)
A measure of pre-mature mortality.
It involves 2 steps:
1. For each cause, each deceased person’s age at death is subtracted from a predetermined (or average) at at death. - in the US, 75 is typically used
- Years of potential life lost for each individual are added together to yield the total YPLL for a specific cause
How are YPLLs used?
- To assist in establishing research and resource priorities
- Surveillance of temporal trends in premature mortality
- Evaluating the effectiveness of program interventions
When is a mortality rate a good measure of incidence
- When the case-fatality is high
- When the duration (survivability) of the disease is short
What is apparent incidence
It can be impacted by an increase in early detection and diagnosis of subclinical cases
What is the underlying cause of death
The disease or injury that initiated the train of morbid events leading directly or indirectly to death of circumstances of the accident of violence that which produced the fatal injury.
What is the single most important predictor of mortality
Age
How is direct age adjustment used
it is a standard population used to eliminate the effects of a difference in age between two or more populations being compared.
What are the caveats about age-adjusted rates?
They are hypothetical
What are possible explanations of trends or differences in mortality in the NUMERATOR
Errors in diagnosis
Errors in age
Changes in coding rules
Changes in classification
What are possible explanations of trends or differences in mortality in the DEMONINATOR
Errors in counting the population
Errors in classifying by demographic characteristics (e.g. race)
Differences in percentages of populations at risk
What are possible explanations for differences in mortality
Change in diagnostic modalities or management strategies
Change in survivorship without change in incidence
Change in incidence
Change in age composition of the population(s)
A mix of these factors
What is a challenge of crude (unadjusted) mortality rates?
hHigher rates may be the outcome of age distributions rates than a true difference in mortality.
When is indirect age adjustment used?
When the number of deaths in each age stratum are not available. We may have the total deaths, but not the breakdown across ages
We compare the observed number of deaths in one population to the expected number of deaths in another.
SMR is a calculation that comes out of direct age adjustment
Direct age adjustment is used when…
We know the age-specific mortality rates of two different populations
