An investigation of the completeness and accuracy of the recording of stroke events (including by subtype) in primary (CPRD) and secondary care databases (HES and ONS)

Date of Approval
Application Number
Technical Summary

The overall aim of this study is to assess the completeness and diagnostic validity of the recording of stroke, by subtype, in primary care using HES as a reference. To this end we will construct - using HES in-patient data - a retrospective cohort of patients who have been hospitalised and diagnosed as having had a stroke. For those patients with linked CPRD-HES records, we will compare various aspects of the recording of individual stroke events across the two data sources. We will conduct a similar exercise using ONS data.

We will assess the completeness of the recording of stroke events in CPRD in a Venn diagram. We will also investigate the level of event date agreement across data sources. If we find a significant proportion of unrecorded stroke events in CPRD, we will perform logistic regression analyses to establish whether factors such as age, sex, year of stroke and mortality are contributing to the suboptimal recording of stroke in primary care. In addition, we will assess the diagnostic accuracy of CPRD stroke recording by subtype (ischaemic, subarachnoid hemorrhagic, intracerebral haemorrhagic, TIAs) and determine the sensitivity and positive predictive value (PPV) of different stroke code sets (all stroke and for stroke subtypes).

Health Outcomes to be Measured

Subarachnoid haemorrhage; intracerebral haemorrhage; cerebral infarction; stroke not specified as haemorrhage or infarction; transient cerebral ischaemic attacks (TIAs) and related syndromes.


Jennifer Quint - Chief Investigator - Imperial College London
Ann Morgan - Corresponding Applicant - London School of Hygiene & Tropical Medicine ( LSHTM )


HES Admitted Patient Care;ONS Death Registration Data