Misleading Death Rate: Underestimating the Crisis?

On May 3, Union Health Minister of India Harsh Vardhan claimed that "Our mortality rate of 3.2% is the lowest in the world.” He is factually wrong in both the claims. He is speaking about fatality rate rather than the mortality rate and fatality rate of India is more than many other countries including Pakistan. The method to calculate fatality rate (death rate) in India is problematic. Everyday, the country is updated with a death rate which seems to underestimate the crisis and thus faulty in nature. Fatality rate is measured to understand the possibility of an infected person dying or surviving due to the infection and thus to understand severity of the said disease. 

Two Measurements of Death Rate: 

The two most widely visited websites for COVID-19 updates give different death (fatality) rates for India. Both the websites measure death rates differently. The first, measures death rate by dividing the total deaths during a certain period of time by the total number of identified cases infected with COVID-19 during the same period of time. This measurement does not take into account the fact that there will be more deaths among those who are tested positive but still under treatment.                      

                                                   Total Death 

Death Rate = ——————————————————————

                       Total Death + Total Recovery + Total Under-Treatment 

The second, on the other hand, calculates death rate by dividing the total number of deaths during a certain period with the sum of total deaths and recovered patients during the same period of time. This calculates the possibility of dying as possible deaths among all who were treated rather than among all who were treated as well as those who are still under treatment. 

As of May 9, 2020, the first measurement claims India’s death rate to be at 3.37 % while the second claims India’s death rate is 10.44 %. 

Run Rate and Death Rate

For example, in a cricket match, the average runs scored by the batting team are measured not by dividing total runs scored by the team with total number of players in the team but instead the total number of runs scored by the team will be divided by total number of batsman who did batting on the pitch. Similarly, the run rates of a team in the middle or particular time of the match is not measured by dividing total runs scored by total overs of the match but instead it is measured by dividing total runs scored at that point of time with total number of overs bowled at that point of time. 

In a cricket match of 50 overs, a team scored 150 runs after 25 overs, what will be the run rate of the A team?

Case 1: Run Rate = 150 runs/ 50 overs (25 overs bowled + 25 overs remaining) = 3 runs per over 

Or

Case 2: Run rate = 150 runs /25 over bowled = 6 runs per over

Similarly, in the process of treating 50 patients with COVID-19, a team of doctors treated 25 patients. Out of 25 patients, five died while 20 survived. What will be the death rate?

Case 1: Death Rate = 5 deaths / 50 (25 treated+ 25 under treatment) = 10 %

Or 

Case 2: Death Rate = 5 death/25 treated (5 death + 20 recovered) = 20 %

Underestimating the Danger 

As explained above, the total five deaths that happened in both the cases should be read as death out of 25 treated patients because rest of the 25 patients are still under treatment and some might die among them too. When some people are currently sick and will die of the disease, but have not died yet, the first measurement will underestimate the true risk of death. The second method is a more appropriate measure to understand the gravity of danger and possibility of dying due to this virus because this excludes those who are under treatment and possible deaths among patients under treatment. The first measurement is misleading because it reduces the actual death ratio. 

Similarly, the sum of recovery rate and death rate of the patients infected with COVID-19 should be 100% because in case of infection, the final outcome of any infection would be either death or recovery. If we measure recovery and death ratio with the second method, the sum of both will be 100% but if we do the same with the first method of measurement, it will not reach even 50%. 

History Repeats Itself

This is not the first time when we are calculating the death ratio of an infection with the wrong method. During the SARS-CoV outbreak in 2003, the case fatality rate was reported to be 3-5% during the early stages of the outbreak, but had risen to around 10% by the end. This happened because we used the first method of measurement, which is misleading. The health minister referred to this method of measurement when he claimed that the mortality rate in India is only 3.2%. 

Misleading Union Health Minister 

Even if you accept the method of measurement used by the Union Health Minister and Covid19india.org, India does not have the lowest mortality (death) rate. Even countries like Pakistan have lower death rates. As on May 7, 2020, according to the health minister’s estimate, mortality rate of India is 3.33% while death rate of Pakistan is 2.27 %. Five hundred and ninety-nine out of a total of 26,434 infected people died in Pakistan due to COVID-19. In India, 1,985 people died out of a total of 59,695 infected people from COVID-19. There are many other countries which have a much lower mortality rate (death rate) given in the table.

Second Mistruth 

Fatality rate and recovery rate (May 9, 2020). Source: Covid19.org

Our health minister is wrong not just in claiming that India has the lowest mortality rate, but he also confused the case fatality rate with the mortality rate. Mortality rate is measured by dividing total death with the total population of the country. Mortality rate is often calculated after the end of any outbreak. Case fatality rate is a more appropriate measurement to understand the magnitude of the crisis while amidst the crisis. Mortality rate is always lower than the case fatality rate. Actually, the minister was referring to the case fatality rate when he gave the data of 3.2% on May 3. 

Case Fatality Rate and Infection Fatality Rate

There are two kinds of fatality rates: “case fatality rate” and “infection fatality rate.” The “infection fatality rate” is impossible to measure as it includes both people tested positive as well as people who died due to infection but were never tested at all. They never come under medical surveillance or observation. So, a person in a remote village who died due to COVID-19, while medical staff does not have any information regarding that case, cremated by villagers is part of “infection fatality rate” but not “case fatality rate.” 

Conclusion

We understand the inability of the Union home minister to calculate infection fatality rate, but he should use a method of calculation that is not misleading or which does not underestimate the danger. Accepting higher possibility of deaths due to COVID-19 may lead to disturbances among the popular masses, but it may also lead to more consciousness towards self-protection. 

Author is a programme manager at Tata Institute of Social Sciences, Mumbai. One can reach him at [email protected].

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