Summary

ACR/Vasculitis Foundation 2021 guideline on management of giant cell arteritis (GCA) and Takayasu arteritis (TAK), the two principal large-vessel vasculitides. Provides 22 recommendations plus 2 position statements for GCA and 20 recommendations plus 1 position statement for TAK, addressing diagnostic imaging/biopsy, induction and maintenance therapy, monitoring, and surgical management. Notable shifts include endorsement of tocilizumab as a glucocorticoid-sparing agent in GCA and continued preference for temporal artery biopsy (over ultrasound/MRI) in the US, diverging from EULAR. Nearly all recommendations are conditional given low-quality evidence.

Key Recommendations

For suspected GCA, obtain unilateral temporal artery biopsy as first-line diagnostic test; biopsy preferred over temporal artery ultrasound or cranial MRI in the US.
Do not delay glucocorticoids while awaiting biopsy — biopsy should be obtained within 2 weeks of starting steroids, but later biopsies can still be informative.
For newly diagnosed GCA without cranial ischemia, start high-dose oral glucocorticoids; reserve IV pulse methylprednisolone for threatened vision loss.
For newly diagnosed GCA, combine oral glucocorticoids with tocilizumab over glucocorticoids alone (methotrexate or GC monotherapy are acceptable alternatives).
Add aspirin in GCA only when there is critical or flow-limiting vertebral or carotid artery involvement; routine statins are not recommended for GCA treatment.
In GCA relapse with cranial ischemic symptoms while on steroids, add tocilizumab (preferred over methotrexate) and increase glucocorticoid dose.
For all newly diagnosed GCA, obtain noninvasive large-vessel imaging (CTA, MRA, PET, or ultrasound) to assess extracranial involvement; maintain long-term clinical monitoring (strong recommendation).
Do not escalate immunosuppression based on isolated rise in ESR/CRP without clinical or imaging signs of activity — observe instead.
For active severe TAK, initiate high-dose oral glucocorticoids plus a non-glucocorticoid immunosuppressive agent (methotrexate, azathioprine, or TNF inhibitor preferred over tocilizumab as initial therapy).
For refractory TAK, add a TNF inhibitor preferentially over tocilizumab; taper glucocorticoids off after 6–12 months of sustained remission.
In TAK, prefer noninvasive imaging (CTA/MRA/PET) over catheter angiography for monitoring, with regularly scheduled imaging in addition to clinical assessment.
For limb/organ ischemia in either GCA or TAK, escalate immunosuppression before considering surgery; delay elective vascular intervention until disease is quiescent and use periprocedural high-dose glucocorticoids if disease is active.

Thresholds & Doses

IV pulse glucocorticoids: methylprednisolone 500–1,000 mg/day (adults) or 30 mg/kg/day in children (max 1,000 mg/day) for 3–5 days.
High-dose oral glucocorticoids: prednisone 1 mg/kg/day up to 80 mg/day.
Moderate-dose oral glucocorticoids: prednisone 0.5 mg/kg/day (typically 10–40 mg/day in adults).
Low-dose oral glucocorticoids: prednisone ≤10 mg/day.
Temporal artery biopsy: obtain within 2 weeks of starting glucocorticoids; long-segment specimen >1 cm preferred over <1 cm.
GCA epidemiology: occurs in patients >50 years, predominantly Northern European descent.
TAK glucocorticoid taper: consider tapering off after ≥6–12 months of sustained remission.
TAK imaging surveillance interval: approximately every 3–6 months early in disease course, longer once quiescent.

Citations

Table 1 — definitions of disease states and glucocorticoid dose categories
Table 2 — GCA diagnostic testing recommendations (PICO 1–9)
Table 3 — GCA treatment, monitoring, and surgical recommendations (PICO 10–27 and relapse questions)
Figure 1 — Overview of GCA treatment algorithm (high-dose oral GC + tocilizumab; IV pulse GC for visual symptoms)
Table 4 — TAK medical and surgical management recommendations (PICO 5–26)
Table 5 — TAK clinical/laboratory monitoring and vascular imaging recommendations
Figure 2 — Overview of TAK treatment algorithm based on clinical/radiographic assessment
Discussion — divergence from EULAR on temporal artery imaging vs biopsy in US practice