Six reasons why it’s a mistake to compare countries’ coronavirus figures

I was inspired to write this piece by a chart made by the historian James Barr. It showed, in the style of the Financial Times’ graphs of coronavirus cases and fatalities in different countries, a comparison of ‘Apples, Pears and Rhubarb’. What was meant as satire perfectly summed up why it is so unwise to compare coronavirus outcomes in different countries. 

We are now facing a catastrophic global crisis where everyone is at risk. This is a new disease attacking different countries, with different cultures, different vulnerabilities and different political systems. Yet many people cannot help but track and compare different countries’ death-tolls and cases like it is a league table. 

When clinical scientists study medical interventions the primary outcomes we measure are deaths from all causes and the quality of life of the patient. All other outcome measures are surrogate. For example, even if a new treatment saves someone’s life, it may also cause one extra death from the toxicity of the treatment.