Mortality Flashcards
Define ‘aggregate data’.
qData collected on groups rather than individuals.
- Often group level statistics for individual level variables.
What are the sources of mortality data?
- Medical Certificate of Cause of Death (MCCD) issued by medical practitioner
- Informant legally obliged to register death with a Registrar at a government Register Office (within 5 days, in England and Wales, and within 8 days in Scotland)
- Data collected: date & place of death, cause of death, date of birth, place of birth, usual address
- Collected by local authorities then collated, classified & disseminated by ONS
How is the mortality data classified?
- Geographical area
- All causes of death
- Specific causes of death
Define an ‘underlying cause’ of death.
The disease or injury that initiated the train of morbid events leading directly to death or the circumstances of the accident or violence that produced the injury.
What is the International Classification of Death (ICD)?
- Global standard for recording health information and cause of death.
- A standard vocabulary & coding system for diseases, enabling systematic comparison of mortality data internationally.
When did ICD-11 officially come into effect?
1 January 2022
How is ICD summarised ?
Commonly summarised at a 3 character level.
How do we calculate the crude death rate?
Total deaths in a year divided by mid-year population * 1000
What is the issue with crude death rate?
It’s a simple measure.
Why can’t you compare data between countries only using the crude death rate?
There’s no control for differences in age/sex structure.
How do we calculate Age Specific Mortality Rates (ASMRs)?
Total deaths in a year of males (or females) aged x *1000
Mid-year population of males (or females) aged x
Why are ASMRs better than the crude death rate?
- Accounts for age
- Accounts for sex (calculated separately for males and females)
- Requires more data
- Plotting ASMRs illustrates strong age/sex pattern of mortality
What is the difference between how infant mortality rates are calculated than other mortality rates?
- Denominator is live births in a year (not mid year population)
- A single rate is calculated for both males and females combined
How do we calculate the infant mortality rate?
(Deaths under age 1 in a year / Live Births in a year) * 1000
List the 4 different types of infant mortality rates (equation for calculation added).
- Stillbirth rate:
(Stillbirths / (Live births + Stillbirths)) * 1000 - Perinatal mortality rate:
((Stillbirths + Deaths under 1 week) / (Live births + Stillbirths) * 1000 - Neonatal mortality rate:
(Deaths under 4 weeks / Live births) * 1000 - Post-neonatal mortality rate:
(Deaths in 4-52 weeks / Live births) * 1000
Why is there a need for standardisation whilst measuring mortality?
- Crude rates include all ages & both sexes BUT the risk of death is strongly related to age & sex.
- Populations differ with respect to age & sex structure so impossible to meaningfully compare mortality using crude rates.
How are crude rates leading to misinterpretation of data?
Crude rates are masking the difference in the actual risk of dying.
What is the solution for comparing different countries’ mortality rates?
- Compare age specific rates
- Generate a single measure controlling for age
What are the two main approaches to standardisation?
- Direct
- Indirect
Why is indirect standardisation more widely used?
- Has fewer data demands than the direct method
- Better with a smaller number of cases
What are the three steps to direct standardisation?
- Apply ASMRs for each population of interest (A, B & C) to a reference population (R), with known age-specific deaths
- Apply ASMRs for each population of interest (A, B & C) to a reference population (R), with known age-specific deaths
- Compare total death rates in reference population (given each study population’s ASMRs) = standardised death rate.
What are the three steps to indirect standardisation?
- Apply ASMRs for reference population (R) to each population of interest (A, B & C)
- Calculate expected deaths in each population of interest by applying reference population’s ASMRs to their age groups.
- For each population of interest, divide total observed deaths (given reference population’s ASMRs) by total expected deaths to give a standardised mortality ratio (SMR)
How do we calculate the standardised death rate?
Sum of expected deaths in standard population divided by
Total standard population
How do we calculate direct standardisation?
- Divide the deaths in each age group by their population = ASDR
- Multiply the ASDRs by the standard population in their age group = expected age deaths
- Add up the total expected age deaths.
- Add up the total standard population.
- Divide the total expected age deaths by the total standard population and multiply by 1000 = standardised rate.
