@bengoldacre provides some useful commentary on a BBC news item about statins. In particular, he notes a detail from the original research paper that didn’t make it into the BBC news item – namely the remarkable lack of agreement between GPs and hospitals as to whether a given patient had experienced a cardiovascular event.
This is not a new observation: it was analysed in a 2013 paper by Emily Herrett and others. Dr Goldacre advised a previous Health Minister that “different data sources within the NHS were wildly discrepant wrt to the question of something as simple as whether a patient had had a heart attack”. The minister asked which source was right – in other words, asking for a single source of truth. But the point is that there isn’t one.
Data quality issues can be traced to a number of causes. While some of the issues may be caused by administrative or technical errors and omissions, others are caused by the way the data are recorded in the first place. This is why the comparison of health data between different countries is often misleading – because despite international efforts to standardize classification, different healthcare regimes still code things differently. And despite the huge amounts of NHS money thrown at IT projects to standardize medical records (as documented by @tonyrcollins), the fact remains that primary and secondary healthcare view the patient completely differently.
See my previous blogposts on Single Source of Truth
Tony Collins, Another NPfIT IT scandal in the making? (Campaign4Change, 9 February 2016)
Emily Herrett et al, Completeness and diagnostic validity of recording acute myocardial infarction events in primary care, hospital care, disease registry, and national mortality records: cohort study(BMJ 21 May 2013)
Michelle Roberts, Statins ‘don’t work well for one in two people’ (BBC News, 15 April 2019)
Benoît Salanave et al, Classification differences and maternal mortality: a European study (International Journal of Epidemiology 28, 1999) pp 64–69