Table 2.

Possible diagnostic permutations in giant cell arteritis during the COVID-19 pandemic arising from diagnostic ambiguity between the two diseases

	First clinical suspicion	Does the patient have active giant cell arteritis?	Does the patient have COVID-19?	Possible treatment approach
New giant cell arteritis	Giant cell arteritis	Yes	No	Treat with high-dose glucocorticoid therapy to prevent vision loss; close follow-up to identify adverse effects; take measures to minimise risk of patient acquiring SARS-CoV-2 during health-care contacts
COVID-19 misdiagnosed as giant cell arteritis	Giant cell arteritis	No	Yes	Avoid inappropriate glucocorticoid therapy; monitor for clinical deterioration; take measures to minimise risk of transmission of SARS-CoV-2 to other patients or staff
New giant cell arteritis and concomitant COVID-19	Giant cell arteritis	Yes	Yes	Treat with high-dose glucocorticoid therapy to prevent vision loss; close follow-up to identify adverse effects; take measures to minimise risk of transmission of SARS-CoV-2 to other patients or staff
New giant cell arteritis misdiagnosed as COVID-19	COVID-19	Yes	No	Treat with high-dose glucocorticoid therapy to prevent vision loss; close follow-up to identify adverse effects; take measures to minimise risk of patient acquiring SARS-CoV-2 during health-care contacts
Giant cell arteritis relapse	Giant cell arteritis relapse	Yes	No	Escalate giant cell arteritis therapy, including adjuvant immunosuppressant, if appropriate; take measures to minimise risk of patient acquiring SARS-CoV-2 during health-care contacts
COVID-19 in a patient with prior diagnosis of giant cell arteritis	Giant cell arteritis relapse	No	Yes	Standard care for COVID-19; if already taking long-term, low-dose glucocorticoids for giant cell arteritis, consider short-term increase in dose to avert potential adrenal crisis, in line with recommendations for adrenal insufficiency11
Giant cell arteritis relapse with concomitant COVID-19	Giant cell arteritis relapse	Yes	Yes	Standard care for COVID-19; escalate giant cell arteritis therapy including adjuvant immunosuppressant if appropriate; take measures to minimise risk of transmission of SARS-CoV-2 to other patients or staff

SARS-CoV-2=severe acute respiratory syndrome coronavirus 2.