When is a death an excess death? Getting behind the numbers
Excess deaths is a relatively new measure, which can be produced quickly and was vital when strategies for controlling the pandemic and assessing its impact depended on having timely data. The need for timely data is still pertinent, but how reliable is excess deaths as a measure?
The Office for Statistics Regulation (OSR) notes that even within the UK there are four agencies that calculate excess deaths using different methodologies of varying complexity: Office for National Statistics (ONS), Office for Health Improvement and Disparities (OHID), Institute and Faculty of Actuaries (IFoA), and UK Health Security Agency. For example, choices about the baselines used for calculating excess deaths differ. And then some organisations (eg, ONS) simply take the difference between the current and baseline numbers of deaths, while others (eg, IFoA) adjust for demographic variables such as changes in population size and age structure, or factor in a wider set of variables including also ethnicity and deprivation (OHID).