• giant cell arteritis
• systemic vascuultralitis
• ultrasonography

We would like to thank Molina Collada et al 1 for their interest in our paper on the ultrasonographic Halo Score in giant cell arteritis (GCA).2 We welcome their effort to validate our findings.

The authors have performed a retrospective analysis of the Southend Halo Score and halo count in a GCA fast-track clinic. The authors report an excellent diagnostic accuracy of the Halo Score/halo count for a clinical diagnosis of GCA. The authors also observed a positive correlation between the Halo Score/halo count and systemic inflammation, that is, C reactive protein levels and the erythrocyte sedimentation rate (ESR). The correlation with ESR may reflect measurement by Westergren or a similar accurate method.

Thus, the study by Molina Collada et al is indeed the first to validate the feasibility and diagnostic performance of the Southend Halo Score in routine clinical care. Their findings confirm that the Halo Score may help to estimate the burden of inflammation in GCA. As previously stated,2 3 we agree with the authors that the Halo Score requires further validation. The utility of the Halo Score for the diagnosis, prognosis and monitoring of GCA disease activity is currently under investigation in prospective, multicentre studies (Halo Score for Giant Cell Arteritis (HAS-GCA) National Institute for Health Research Portfolio study #264 294 and ClinicalTrials. gov, NCT03765788). The practicality of the Southend Halo Score and halo count, as recently discussed,4 could be an important advantage in this context. There is a need for an intrarater and inter-rater reliability exercise to validate these quantitative assessments, and this is planned for the eighth International Ultrasound Workshop on GCA, large-vessel vasculitis and polymyalgia rheumatica at Southend in March 2021.