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

Abstract

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

Disclosure

The abstract of this paper was presented at the European Congress of Rheumatology 2019 as a poster presentation with interim findings. The poster’s abstract was published in “Poster Abstracts” in Annals of the Rheumatic Diseases (ARD): http://dx.doi.org/10.1136/annrheumdis-2019-eular.6852.

Berit Dalsgaard Nielsen reports personal and speaker’s bureau fees from Roche and consulting fee from Sanofi, outside the submitted work. Ellen-Margrethe Hauge reports grants from Aarhus University and Danish Rheumatism Association, during the conduct of the study; grants from Danish Regions Medicine Grants, Novo Nordic Foundation, Roche, and Novartis, and travel expenses from Sobi, outside the submitted work. The authors report no other possible conflicts of interest in this work.

Additional information

Funding

This study was supported by the Danish Rheumatism Association (grant number: R163-A5661 and R155-A4747) and Aarhus University.