By Richelle Kihoro, MPH Student, University of Nairobi
Africa CFRs are lower than other continents in the world (Figure 1). A study hypothesized that the low morbidity and mortality rates experienced in Africa were as a result of many factors one of them being age. Africa has a more youthful population, with a median age of < 20 years as compared to Europe and the USA whose median age is > 38 years. This hypothesis and other hypothesis cited in the study such as favorable weather may be possible reasons for low morbidity and mortality in the continent as compared to other continents. However, how do we compare the case fatality rates (CFRs) among different countries in the African continent?
Case fatality rate (CFR) is an epidemiological term used to estimate mortality. It calculates the proportion of deaths/ fatalities among identified confirmed cases. Fatality rates are used by epidemiologists to understand the severity of a disease, identify the at-risk population and evaluate the quality of healthcare. According to the latest Africa CDC report released on 20th October 2020 twelve countries are reporting case fatality rates higher than the global case fatality rate of 2.8%. The countries are (Table 1);
|Country||Case Fatality Rate (CFR)|
|Sahrawi Arab Democratic Republic||7.1%|
Comparing the estimates at face value such as saying that Malawi’s health care system is doing better in terms of managing COVID-19 than Chad’s health care system is a statement that has little meaning. A better way of comparing African countries and their CFRs is by utilizing age adjusted or age- specific COVID-19 CFRs.
A study published of seven countries reveal that crude CFRs for COVID-19 vary between countries and comparing them as crude estimates is erroneous. The study found out that when the fatality rates were adjusted for the differences in age the variations in age specific CFRs were much smaller. The data was obtained from open access aggregative and anonymous data from Israel, South Korea, China, Spain, Sweden, Italy and Canada.COVID-19 cases and deaths, by ten-year age groups was obtained and the overall and age specific CFRs were computed for each country. The results confirm the unhelpful nature of crude CFRs for country-level comparisons. The authors noted that “The substantial reduction in the differences in the age- adjusted CFRs suggest that differences in the standard of healthcare between these countries may not play as important role in affecting the death rates as some have hypothesized.”
The latest updated situation report for Kenya dated 27th July 2020 breaks down the case fatalities by age and sex (Figure 1).
These case fatalities distributed by age can then be used to compare CFRs in different age groups and different countries in the African context. Any attempt to report crude CFRs will fail to account for the differences in risk factors such as age in the population. Calculating age specific estimates of CFRs better describe the true pattern of fatality in a population and these measures can be used to compare CFRs across different countries.
African countries should make their case fatality data easily accessible and should aggregate the data by age. This will allow evidence-based research to be published that can easily compare CFRs between different African countries. This will then lead to generation of policies that are backed up by evidence.