Module 2 Section 3

Question 1

Crude Mortality Rates

Answer 1

• While incidence and prevalence measure the number of people who get and have a disease, they do not describe how or why people stop having that disease. These measures do not explain whether those infected are cured of the disease, die of the disease, or die of another cause altogether. Crude mortality rate is the count of all the deaths over a specified time period divided by the population at the midpoint of the time period being considered. Just like incidence and prevalence, it is often reported per 100,000 people and the time period is usually a year

Crude Mortality Rate = # of deaths over a time period × 100 000 / population at midpoint of time
period

Question 2

Two Types of Crude Mortality Rates

Answer 2

• All-cause mortality rate: considers deaths for any reason in the population
• Cause-specific mortality rate: measures the deaths in a population from a specific disease

Question 3

Defining Population Subgroups

Answer 3

Sometimes epidemiologists are more interested in the mortality of a small subgroup of a population. In this case, instead of calculating crude mortality rate, they calculate a specific mortality rate that is accurate for only a fraction of the population in question

Question 4

How do you think population subgroups could be defined?

Answer 4

• Age
• Sex
• Race
• Other demographic factors

Question 5

Calculating Specific Mortality Rate

Answer 5

• Calculating specific mortality rate is very similar to calculating crude mortality rate. However, with specific mortality rate, the numerator only encompasses the deaths of individuals who meet the sub- group criteria, while the denominator encompasses the total number of individuals that meet the criteria

Specific Mortality Rate = # of deaths over a time period (in a certain subgroup) × 100 000 / subgroup population at midpoint of time-period

Question 6

Specific Mortality Rates

Answer 6

• Consider the mortality rates in Canada attributed to COVID-19 for those with diabetes and those without diabetes.
• What are the two specific mortality rates that are being compared and what information would you need in order to calculate these rates?
• The two specific mortality rates being compared are COVID-19 cause-specific mortality of individuals with diabetes and COVID-19 cause-specific mortality of individuals without diabetes.
• The information needed to calculate these rates includes:
  * The number of deaths due to COVID-19 in both patients with and without diabetes;
  * The proportion of individuals with and without diabetes in the Canadian population, during the time-period in question.

Question 7

Standardizing Mortality Rates

Answer 7

• Standardization of mortality rate is used when comparing the mortality in two populations that differ in terms of characteristics that are known to influence mortality (i.e. age, sex, etc.). Crude and specific mortality rates don’t take sex, age, or the general composition of a population into account. As a result, they can be misleading. The most common metric to standardize mortality by is age
• For this course you will not need to know how to calculate standardized death rates but you will need to know why they are important and what limitations are put on interpreting crude rates as a result.

Question 8

What might be the reason for the higher mortality rate from Alzheimer’s and Dementia in Canada compared to Chad?

Answer 8

Alzheimer’s is an illness that typically affects older people. When comparing Canada to Chad, Canada has a greater proportion of older citizens. This, along with the fact that Canada probably has better diagnosis and tracking, would translate to Canada having a higher Alzheimer’s and Dementia mortality rate.

Question 9

What might be the reason for the change in trends between Canada’s and Chad’s Alzheimer’s mortality rates?

Answer 9

• Alzheimer’s is an illness that typically affects older people. As per the population pyramids for both countries in 2010 and 2020, the demographics did not drastically change. Yet, we see that Canada went from having a higher mortality rate than Chad to having a lower mortality rate. As well, Canada’s mortality rate per 100 000 decreased, while Chad’s rate increased
• There is no one mechanism that can be attributed to these changes, rather several factors could be driving this change. These factors include:
  
  • Changes in sampling - there is likely an increase in surveying and reporting of Alzheimer’s in Chad, and therefore an increase in mortality
  • Healthcare quality - in Canada there are more widely accessible options for treatments and therapies compared to in Chad
  • Changes in diagnostic criteria - with such changes, it could be that cases that were previously considered to be Alzheimer’s/Dementia are now being diagnosed as something else
  • Possible false data in the magazine/google search - always be wary of your sources of data

Question 10

Measurement Limitation in Developing Countries

Answer 10

In developing countries it can be difficult to obtain reliable measurements of population morbidity and mortality. This is due to many factors. In some countries, the system and where and how people live, make it difficult for vital event registration to be up to date. Additionally, many people die at home, never having been to a health facility

Question 11

Vital event registration

Answer 11

• A system by which a country’s government records and tracks statistics on any vital events, including births, deaths, marriages, divorces, and fetal deaths.
• Such a system creates a permanent record for every event and statistics on population dynamics and health indicators on a continuous basis. It also helps quantify the prevalence, distribution, and causes of mortality, while identifying health inequalities

Question 12

Overcoming Measurement Limitations in Developing Countries - Video 1

Answer 12

• This video discusses the challenges of measuring global health, particularly in underdeveloped countries where most of the population is not registered. Ed Fel, a senior research fellow in epidemiology, explains how limited data makes it hard to measure deaths and the causes of death, which are essential for public health planning. Traditional methods like surveys and verbal autopsies, which involve interviewing family members of deceased individuals to determine the cause of death, are used. However, these methods can be slow, costly, and unreliable.
• The new approach is to use technology, particularly mobile phones and computers, to capture and analyze data in real-time. By using probabilistic models to interpret verbal autopsies, the process can be faster and more reliable. These devices can also provide immediate feedback to the families. This technological shift offers a promising solution to more accurately track deaths and health issues in global health, which could lead to more effective public health strategies and better global burden of disease estimates. However, there are ethical concerns regarding how sensitive health information should be handled and communicated.

Question 13

Overcoming Measurement Limitations in Developing Countries - Video 2

Answer 13

• This segment focuses on the challenges of determining the cause of death in low-income countries, where most deaths occur outside healthcare facilities, often in homes. These deaths are typically caused by acute conditions that prevent individuals from reaching a health center, making it difficult to accurately determine the cause of death. Relying solely on data from health facilities can create a biased and inaccurate picture of the disease burden in a population, leading to misaligned health policies.
• To address this issue, the practice of verbal autopsy has been used. This method involves interviewing family members or caregivers of the deceased at home to gather information about the symptoms and circumstances before death. The interviews are structured with questions tailored to different age groups, including infants, children, and adults, and even those who died from maternal causes.
• The gathered data is reviewed by medical professionals or analyzed by computers using statistical methods to identify the most likely cause of death. This technique provides a more accurate picture of the true causes of death in a community, particularly in cases where the individual did not have access to medical services. Verbal autopsy allows for the aggregation of data from entire populations, leading to more reliable health data. With this data, health policies can be better aligned with the true needs of the population, and trends in causes of death can be monitored over time, even in dispersed areas.