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Positive Predictive Value of the Giant Cell Arteritis Diagnosis in the Danish National Patient Registry: A Validation Study

Authors Hjort PE, Therkildsen P, Nielsen BD, Hansen IT, Nørgaard M, de Thurah A, Hauge EM

Received 17 April 2020

Accepted for publication 11 June 2020

Published 12 July 2020 Volume 2020:12 Pages 731—736


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Professor Henrik Toft Sørensen

Peter Engholm Hjort,1,2,* Philip Therkildsen,1,2,* Berit Dalsgaard Nielsen,1– 3 Ib Tønder Hansen,1,2 Mette Nørgaard,2,4 Annette de Thurah,1,2 Ellen-Margrethe Hauge1,2

1Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark; 2Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; 3Diagnostic Centre, Silkeborg Regional Hospital, Silkeborg, Denmark; 4Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark

*These authors contributed equally to this work

Correspondence: Philip Therkildsen
Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark

Purpose: To investigate the positive predictive value (PPV) of the giant cell arteritis (GCA) diagnosis in the Danish National Patient Registry (DNPR).
Patients and Methods: A total of 293 patients aged ≥ 50 years with a first-time diagnosis of GCA in the DNPR between January 2012 and December 2017 were included. Patients were sampled from two secondary and one tertiary care hospitals in the Central Region Denmark. Two independent investigators (PH & PT) reviewed all medical files, including medical records, treatment, biochemistry, histopathology and imaging, and either confirmed or dismissed the diagnosis of GCA. In case of disagreement, a consensus agreement was reached. Sub-analyses including number of redeemed prescriptions performed temporal artery biopsies (TABs), and number of GCA-related hospital contacts were performed.
Results: We confirmed the diagnosis of GCA in 183/293 patients resulting in a PPV of 62% (95% CI: 57– 68). In patients with ≥ 3 redeemed prescriptions of glucocorticoids (GCs), we confirmed the diagnosis in 166/214 resulting in a PPV of 78% (95% CI: 71– 83). In patients with ≥ 3 redeemed prescriptions of GCs and ≥ 3 GCA-related hospital contacts, we confirmed the diagnosis in 88/95 resulting in a PPV of 93% (95% CI: 85– 96); however, this only included 88/183 confirmed GCA patients.
Conclusion: This is the first study to validate the diagnostic code of GCA in the DNPR. The overall PPV of GCA in the DNPR was 62%. Requiring redeemed prescriptions of GCs and/or GCA-related hospital contacts increase the PPV, but also excludes a significant number of GCA patients.

Keywords: rheumatology, giant cell arteritis, validation, positive predictive value, Danish National Patient Registry

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