Comment on: Diagnostic accuracy of ultrasound for detecting large-vessel giant cell arteritis using FDG PET/CT as the reference

DearEditor, We read with great interest the recent article by Nielsen et al. in which the authors elegantly evaluated the accuracy of vascular ultrasound (US) in diagnosing large-vessel GCA [1]. We particularly appreciated their effort to produce a diagnostic algorithm that can help clinicians in evaluating new patients referred with a suspect of GCA. We agree with the authors that a proper evaluation should start with a clinical assessment, performing US examination as the first-line imaging test and other more intrusive investigations when diagnosis remains uncertain.

The starting point of their diagnostic algorithm relies on a clinical pre-test probability of having GCA. Regarding this pre-test probability, the authors stated that it has not been specified yet. However, our group has already proposed a feasible tool for risk stratification of new patients with suspected GCA, called the Southend Probability Score [2]. In this score, patient’s clinical features are analytically approached and grouped into five major clusters (i.e. demographic, timing, laboratory results, symptoms and signs). Each cluster is composed of one or more items that are graded according to their weight towards a GCA diagnosis. In addition, a sixth category is included that accounts for alternative diagnoses possibly justifying the clinical picture and has a negative weighting on the final score. The final score, obtained by the sum of every single item, allows the classification of each patient into three alternative categories, according to his probability of having GCA: low, intermediate and high.

The Southend Probability Score was built and validated after a retrospective analysis of 122 consecutive patients referred to our Fast-Track Clinic over 12 months. In addition, it has been recently demonstrated to enhance vascular US performance through its application on a different cohort of 354 patients evaluated in a 24-month period [3] .

When we conceived this score, we also built a diagnostic algorithm that allows discharge with no additional tests of the low-probability patients with negative US and also performance of a firm diagnosis of GCA in high-probability patients with positive US. Additional tests (e.g. temporal artery biopsy, PET-CT, magnetic resonance/CT angiography) are instead required for patients who fall in all the remaining categories (i.e. low-probability score with positive US; intermediate-probability score; high-probability score with negative US) [2]. Not surprisingly, our diagnostic algorithm largely resembles the one proposed by Nielsen et al. [1], despite theirs having been constructed through a different approach.

We therefore believe that the Southend Probability Score might be well-integrated in the diagnostic algorithm elaborated by Nielsen et al. and it could provide a useful pre-test tool to stratify patients before US is performed.

Funding: No specific funding was received from any funding bodies in the public, commercial or not-for-profit sectors to carry out the work described in this manuscript.

Disclosure statement: The authors have declared no conflicts of interest.

Data availability statement

Data are available upon reasonable request by any qualified researchers who engage in rigorous, independent scientific research, and will be provided following review and approval of a research proposal and Statistical Analysis Plan (SAP) and execution of a Data Sharing Agreement (DSA). All data relevant to the study are included in the article.

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