Flip Flop Flu (part 2)

With the NHS straining under impressive levels of seasonal respiratory infection I decided to take a closer look at influenza and pneumonia

In part 1 of this series I produced a graph of crude mortality for influenza and pneumonia dating back to 1901. We observed the impact of coding changes during a trial period 1984 – 1991 along with implementation of a new system in 2001 that served to de-emphasise the role of respiratory disease by reducing numbers of deaths in official counts. I promised to provide a bit of background to these coding changes so get the kettle on, pop some toast under the grill and pull up a chair…

WHO Rule 3

Officers at the Office for National Statistics tell me that implementation of WHO rule 3 generated these historic coding changes and have kindly pointed me to a ONS national mortality status report that was laid before parliament back in 2006 that usefully summarizes the changes. I have secured a copy of this document, which may be found here, and present a few choice extracts for contemplation:

In general, the main change in introducing automated cause coding was in the interpretation of WHO Rule 3…