Can judgments according to case fatality rate be correct all the time during epidemics? Some lessons from Coronavirus 2019-nCoV case fatality rate index in Iran CURRENT

Background: Coronavirus 2019-nCoV was first identified in China in 2019. One of the most important indices noticed by experts, policymakers and managers which is daily evaluated in epidemics and a lot of judgments are made based on it, is case fatality rate (CFR) index of the disease. CFR can change during epidemics. This study aims to calculate CFR index for nCov-2019 in Iran and answer the following question: Is it right to base judgment on CFR all the time during epidemics and is it right to judge based on that since the outbreak of an epidemic? Methods: This research is a descriptive study. Its required data was obtained from the website of The Ministry of Health and Medical Education of Iran from February 20 th 2020 until March 14 th 2020. CFR index was calculated when the death toll of a disease is divided by the total number of people infected by that disease. Excel 2013 software was used to a1nalyze the data. Results : According to the findings of this study, In Iran, until March 14 th 2020, 11364 people have been infected by Coronavirus 2019-nCoV and 514 people died of it. CFR index had a descending trend and it was 100%, 18.6%, 8.8%, 3.1%, 3.3%, 4.5% on the first, fifth, tenth, fifteenth, twentieth and twenty fifth day, respectively. Conclusion : In emerging epidemics, an index must not be based to judge a health system’s performance until that epidemics condition has not been clarified. It would be suggested that in the outbreak of an epidemic, specifically emerging diseases, CFR must not be the base of judgment. Making judgments, specifically, in the outbreak of emerging epidemics based on fatality rate can lead to an information bias.


Background
Coronaviruses are a big family of viruses. Some coronaviruses cause diseases in human and some others in animals such as bats and camels. Human coronaviruses typically cause mild diseases. According to the published world statistics, the number of identified people infected by coronavirus was 145332 (until March 14th 2020) out of which 70921 people were recovered and 5416 people died; the reported fatality rate of this disease among people has been 3.7% so far. According to the existing evidences, the emergence of this disease in almost 91% of people is mild and in 9% is severe [5].
In Iran, the first positive case of Coronavirus 2019-nCoV was confirmed in February 20th 2020 in Qom city and until March 14th 2020, the total number of cases in the country was 11364 people out of which 3529 people were recovered and 514 people died [6]. According to world statistics, up to now, Iran has reported the most positive cases of coronavirus after China (80815) and Italy (17660) [5].
One of the most important indices noticed by healthcare experts, policymakers and managers in epidemics, specifically in emerging epidemics, is CFR index. This index is obtained by dividing the death toll caused by a disease by the total number of people infected by the same disease. In most cases, this index is utilized for specific epidemics of acute diseases such as cholera during which all patients are under treatment in a specific period of time and this makes it possible to calculate the death toll caused by a disease. The index of CFR indicates the fatality potential of a disease and it just includes the proportion of death toll to the number of patients. This index can be used to describe fatality trend and its general changes, making decisions for healthcare priorities, resource allocation, planning intervention programs and evaluation and refining problems and plans for public health and it can terrify a society in case of emerging epidemics when it is reported high [8,7]. In Iran and many other countries, in the outbreak or in the middle of Covid19, some interpretations were put on CFR.
These interpretations were sometimes published on social news networks and cause fear among people and put pressure on countries' health system. In Iran, given the fact that in the outbreak, this index was high, there were different interpretations on the fatality rate of this disease and based on that, different judgments were made concerning the health systems. In this study, we were in search of this index trend during different time intervals of this epidemic's outbreak. In other words, this 4 study made an effort to answer the following question: Is it right to base judgment on CFR at each stage during epidemics and is it right to judge based on that since the outbreak of an epidemic? Methods This is a descriptive study. The required data for it was obtained from the website of The Ministry of Health and Medical Education of Iran from February 20th 2020 until March 14th 2020 (6). This data was daily published. CFR has been obtained by dividing the death toll caused by a disease by the total number of people infected by the same disease [8] (formula 1).

Case Fatality Rate=
Eq. (1) It is worth mentioning that since the denominator of this fraction is the number of the patients referring to medical centers; it is possible for this CFR index not to be correct. Excel 2013 was used to analyze the data.

Results
As can be seen in Table 1, until March 14th 2020, the total number of the identified infected cases in Iran was 11364 out of which 3529 people have been recovered and 514 patients died. This table shows the number of the identified cases since the outbreak and the number of perished people on different days. The index of CFR has had a descending trend such that the amount of this index on first, fifth, tenth, fifteenth, twentieth and twenty fifth day was 100%, 18.6%, 8.8%, 3.1%, 3.3% and 4.5% respectively.

Conclusion
It would be suggested that, during the outbreak of epidemics, specifically, emerging diseases, judgments not be based on CFR. It is expected to identify the most emerging epidemics during their outbreak when they are severe and probably lead to death. Making judgments based on fatality, specifically, in the outbreak of emerging epidemics can lead to information bias. It should be noticed