The confounded crude case-fatality rates (CFR) for COVID-19 hide more than they reveal—a comparison of age-specific and age-adjusted CFRs between seven countries

Abstract

Background Crude case-fatality rates (CFRs) for COVID-19 vary widely between countries. There are serious limitations in the CFRs when making comparisons. We examined how the age distribution of the cases is responsible for the COVID-19 CFR differences between countries. Methods COVID-19 cases and deaths, by ten-year age-groups, were available from the reports of seven countries. The overall and age-specific CFRs were computed for each country. The age-adjusted CFRs were computed by the direct method, using the combined number of cases in all seven countries in each age group as the standard population. A meta-analytic approach was used to obtain pooled age-specific CFRs. Findings The crude overall CFRs varied between 0.82% and 14.2% in the seven countries and the variation in the age-specific CFRs were much smaller. There was wide variation in the age distribution of the cases between countries. The ratio of the crude CFR for the country with the highest CFR to that with the lowest (6.28) was much lower for the age-adjusted CFRs rates (2.57). Conclusions The age structure of the cases explains much of differences in the crude CFRs between countries and adjusting for age substantially reduces this variation. Other factors such as the definition of cases, coding of deaths and the standard of healthcare are likely to account for much of the residual variation. It is misleading to compare the crude COVID-19 CFRs between countries and should be avoided. At the very least, age-specific and age-adjusted CFRs should be used for comparisons.

Sex differences in the case-fatality rates for COVID-19—A comparison of the age-related differences and consistency over seven countries

“…While incidence rate is directly related to exposure, the case-fatality proportion, which is the proportion of deaths among the cases during a specified period of time is a measure of the severity of the disease. It is commonly referred to as the case-fatality rate (CFR) [ 5 – 7 ] and has been reported as being higher in males than females [ 8 ]. Since the CFR does not contain any measure of the population exposed, it is less likely to be affected by exposure of the cases [ 9 , 10 ].…”

Comparisons between the Neighboring States of Amazonas and Pará in Brazil in the Second Wave of COVID-19 Outbreak and a Possible Role of Early Ambulatory Treatment

“…Comparisons between countries of Africa, Asia, Europe, Central, North and South America, and Oceania were performed [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Most of these studies analyzed the diverse strategies in combating the disease and report parameters involving the number of cases and the mortality.…”

“…Most of these studies analyzed the diverse strategies in combating the disease and report parameters involving the number of cases and the mortality. Some of the studies involved themes such as testing coverage [ 23 ], economic valuation [ 24 ], response strategies [ 25 ], age distribution [ 26 , 27 ], and seasonal climate changes [ 28 ], among others.…”

“…Most of the mentioned comparisons studies [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ] involve the first wave of COVID-19 outbreaks, and two of them were focused more specifically on Brazil and its states [ 32 , 33 ] analyzing results until 16–19 May 2020. The objective of the present work is to make comparisons between the neighboring states of Amazonas and Pará in Brazil in the second wave of the COVID-19 outbreak.…”

Decomposing Differences in Coronavirus disease 2019-related Case-Fatality Rates across Seventeen Nations

“…Also relevant are the sociodemographic, structural, and environmental risk factors associated with Covid-19-related CFR. For example, Covid-19 is substantially more lethal in older persons, and CFR rises sharply with age, from an estimated 0.02%-0.32% in the 30-39 age group and 1.12%-10.89% in the 60-69 age group, to 5.68%-26.69% in the 70-79 age group and 13.4%-38.44% in those aged 80 years or older [5][6][7][8]. In addition to the devastating impact of Covid-19 on the elderly, individuals with obesity are greatly affected by SARS-CoV-2 in terms of the risk of hospitalization [9].…”