Patient coding and the ratings game

Dear Editor

Nigel Hawkes’ article on Dr Foster’s mortality data highlights the
difficulties that hospital trusts face when dealing with variation in
coding practice between hospitals.[1] It is also important to note that
the way primary diagnosis is captured at coding has an important influence
on standardized mortality rates (SMRs). The table (source: Dr Foster) below
shows the 2009 mortality rates for cerebrovascular accidents (CVAs)of
various trusts in the Eastern region . It is clear that some trusts code
their CVAs more specifically than others. Most patients admitted with a
CVA will have brain imaging within 24 hours of admission and it is
therefore now possible to categorize the CVA to infarction or haemorrhage
accurately soon after admission. Whilst some trusts use this definitive
diagnosis as the primary diagnosis, others may just use the provisional
diagnosis made at admission (that is, before any brain imaging) as the
primary diagnosis. The provisional diagnosis is often a CVA of unspecified
cause. This difference in coding practice is important as trusts with more
accurate coding of their CVAs will be compared with trusts whose coding is
not so specific, resulting in a skewed analysis of mortality rates. Dr
Foster’s data will be very valuable if coding practice is uniform across
the trusts. We urgently require a set of stringent national guidelines on
coding aiming to reduce coding variation.

1. Nigel Hawkes. Patient coding and the ratings game. BMJ 2010;340:c2153,
doi: 10.1136/bmj.c2153

Competing interests:
None declared