An epidemiological study of Antiphospholipid Syndrome using electronic health records

Date of Approval
Application Number
16_051
Technical Summary

Antiphospholipid syndrome (APS) is a disorder of the immune system that causes an increased risk of arterial and venous thrombosis. People with APS are at risk of developing conditions such as deep vein thrombosis, pulmonary emboli, myocardial infarction and stroke. Pregnant women with APS also have an increased risk of recurrent miscarriage, intrauterine growth restriction and late pregnancy loss, although the exact reasons for this are uncertain. It is estimated that APS is responsible for one in every ten cases of deep vein thrombosis (DVT), one in seven strokes and one in nine heart attacks and one in every six cases of recurrent (three or more) miscarriages. However, these estimates are not based on sound epidemiological data. There have been few epidemiological studies of APS. Most reports to date have been of clinic-based case series. The only data on mortality are from a European registry study from tertiary referral centres. We aim to add to knowledge concerning the epidemiology of APS by implementing a descriptive epidemiological study in CPRD. We expect to analyse data for more than 2,000 cases from 1990 to 2015. We aim to describe the age at diagnosis, duration and type of symptoms before diagnosis, prognosis and mortality, and patterns of treatment. A validation study will be done to confirm APS diagnoses by sending a questionnaire to the GPs of affected patients. This information will increase understanding of the condition and contribute to earlier recognition and possibly better treatment.

Health Outcomes to be Measured

We will evaluate the clinical features of the CPRD APS cohort. This will be done by evaluating the frequency distribution of READ codes, and READ terms, in the clinical and referral records of study patients. Venous thrombosis, myocardial infarction, stroke, miscarriage and fetal death will be specifically evaluated. The presenting features and delay before diagnosis will be described. Comorbidities, including systemic autoimmune diseases in patients with secondary APS will be evaluated. Patterns of treatment including use of anticoagulants, antiplatelet drugs, steroids and immunosuppressive drugs will be described. The distribution of cases by deprivation quintile will be evaluated.

Collaborators

Martin Gulliford - Chief Investigator - King's College London (KCL)
Martin Gulliford - Corresponding Applicant - King's College London (KCL)
David D'Croz - Collaborator - King's College London (KCL)

Linkages

HES Admitted Patient Care;ONS Death Registration Data;Practice Level Index of Multiple Deprivation