P203 Comparison of coding of giant cell arteritis in primary and secondary care records: an observational feasibility study
Authors: Padmanabhan Nishita , Muller Sara , Bailey James , Helliwell Toby , Mackie Sarah L , Mallen Christian D , Roddy Edward 
Published: April 2023

Abstract

Background/Aims
Giant cell arteritis (GCA) is considered a medical emergency, and relapses are common, affecting around 50% of patients. Many of the early symptoms of GCA are non-specific and highly prevalent in older people, making the diagnosis challenging.
The Clinical Practice Research Datalink (CPRD) is a large primary care database that provides the opportunity to study large numbers of people with GCA. General practitioners commonly identify suspected GCA and refer patients to secondary care for specialist evaluation and diagnostic confirmation. We sought to understand how primary and secondary care records correspond.

Methods
A retrospective observational study was undertaken using data from 2003 to 2020 by linking CPRD Aurum to Hospital Episode Statistics (HES) Admitted Patient Care (APC) and Outpatient (OP) data. We included all permanently registered patients aged 50 years and over in CPRD Aurum who could be linked to HES datasets. We identified individuals with a SNOMED code for GCA in CPRD Aurum and compared them to a list of patients who received an ICD-10 code for GCA in HES APC and OP datasets. We then restricted our comparison to the time-periods 90 and 180 days before or after the first record of GCA in the CPRD Aurum dataset (index code).

Results
We identified 18,806 individuals with a SNOMED code for GCA in the CPRD Aurum dataset between 2003 and 2020. 9755 (51.87%) of these individuals also received at least one secondary care code for GCA in the HES APC and OP data. 3914 (20.86%) and 4573 (24.37%) individuals received at least one secondary care code for GCA within 90 and 180 days, respectively, of the index primary care code. 7520 (58.96%) of those with two codes in primary care also had at least one code in secondary care, and 6090 (61.09%) of those with three codes.

Conclusion
Approximately one-half of individuals with an index code in primary care had a secondary care code for GCA. However, less than a quarter of patients had secondary care codes within 90 and 180 days of their index code in primary care. Given that it is unlikely that coding in either primary or secondary care is inaccurate, we conclude that this method of comparing GCA diagnoses is not a suitable approach to assess the accuracy of primary care coding. Further research could explore alternative approaches to understanding the quality of the coding of GCA in primary and secondary care data.
Disclosure
N. Padmanabhan: Other; NP is an NIHR Academic Clinical Fellow. S. Muller: Other; SM is part-funded by the NIHR Applied Research Collaboration West Midlands (ARC WM). J. Bailey: None. T. Helliwell: None. S.L. Mackie: Consultancies; SLM has provided consultancy on behalf of her institution for Roche/Chugai, Sanofi, AbbVie and AstraZeneca. Other; SLM has given talks on behalf of her institution for Pfizer, Vifor and UCB. In all cases fees were paid to her institution and no personal fees were received, SLM was supported by Roche to attend EULAR2019 and by Pfizer to attend ACR2021 virtually, SLM has been an investigator on clinical trials for Sanofi and GSK. As a research grant co-applicant, SLM has received research funding (partial salary support) from Vifor, paid to her institution. C.D. Mallen: Other; CDM is funded by the NIHR School for Primary Care Research and the NIHR Applied Research Collaboration West Midlands (ARC WM). E. Roddy: None.