Rare diseases

Rise in giant cell arteritis cases during pandemic points to potential trigger

A rise in cases of giant cell arteritis (GCA) during the COVID-19 pandemic’s spring peak in the UK offers limited support for a theory suggesting viral aeitopathogenesis of the condition.

“Previous work has examined the potential role of viruses such as varicella zoster proposed as potential triggers in GCA,” wrote study authors led by Rosamond Luther, of the Royal National Hospital for Rheumatic Diseases in Bath.

GCA, an emergent condition in older adults that can lead to sight-loss or stroke if untreated, is diagnosed using temporal artery ultrasound and, if necessary, temporal artery biopsy. In 2019, the authors’ centre’s fast-track assessment service assessed 128 patients, of whom 28 (22%) were diagnosed with GCA.

Through the end of September 2020, the assessment service has already received 118 referrals, 50 of whom (42%) were diagnosed with GCA. Of the 50 diagnoses, 24 were made in the 12-week period between April and June – a rate nearly five times higher than the rate of GCA diagnoses made in the same period the year before.

The service has performed a median of 11 temporal artery ultrasound studies each month since January 2015; in April 2020, the number was only nine, but this rose to 29 assessments in May and 21 in June.

In that 12-week period of 2020, six of the 24 patients (25%) diagnosed with GCA had associated visual impairment; in 2019, only 10% of those diagnosed had such visual involvement. There was also a higher proportion of male patients diagnosed in 2020 than in previous years.

“Additional work is required to establish whether our local experiences represent a broader rise in GCA diagnoses across the UK,” the authors wrote in Rheumatology Advances in Practice.

“If confirmed, potential drivers may include psychological stress, shifts in previously identified seasonality, or COVID-19 itself.”

None of the patients diagnosed with GCA had COVID-19 symptoms, and at the time coronavirus testing was not being performed in asymptomatic individuals. The authors noted, though, that asymptomatic infections have been widely reported, including in older adults.

“Our findings support the viral aetiopathogenesis hypothesis for GCA and highlight the importance of maintaining urgent access to rheumatology services during this time of uncertainty and re-organisation of healthcare services,” they concluded.

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