Background/Purpose: Prospective trials evaluating methotrexate (MTX) as adjunct immunosuppression in giant cell arteritis (GCA) have provided evidence of a modest benefit for reducing risk of relapse and decreasing glucocorticoid (GC) use. Limited information is available regarding the use of MTX in routine clinical practice. The purpose of this study was to determine the effect of MTX on relapse risk and GC use in a large, single-institution cohort of patients with GCA.

Methods: A retrospective review of patients diagnosed with GCA from 1998-2013 was performed. Patients diagnosed with GCA were ≥ 50 years and had either a temporal artery biopsy (TAB) that was consistent with GCA or radiographic evidence of large-vessel vasculitis. Each patient with GCA treated with adjunct MTX (case) was matched to a similar GCA patient without MTX (control). Cases and controls were matched on age, sex, disease duration at start of MTX and initial GC dose. Each control was assigned an index date that matched the start date of MTX in cases. Baseline demographics, disease characteristics and relapse events were abstracted. GC requirements and relapse events before and after MTX initiation (or corresponding index date) were compared using rate ratios.

Results: A total of 84 patients with GCA receiving MTX were identified and compared to 84 patients with GCA receiving only prednisone. Mean age at diagnosis 69.5±7.0 years in cases and 70.3±6.9 in controls. No significant differences in demographics, laboratory parameters or baseline disease characteristics were observed between groups. Mean initial prednisone doses were similar (53.5±15.8 mg/day in cases, 55.0±13.5 mg/day in controls). The median (interquartile range [IQR]) time from GCA diagnosis to MTX initiation in cases was 0.7 (0.3, 1.6) years and the median (IQR) starting dose was 13.5 (10, 15) mg per week.

Prior to MTX initiation the observed relapse rate was 11.8 relapses per 10 person-years and decreased to 3.69 relapses per 10-person years following initiation. The rate ratio comparing relapse rates observed after MTX to the rate prior to MTX initiation was significantly reduced; rate ratio (95% CI): 0.31 (0.24, 0.41). In the control group the relapse rate was 3.42 relapses per 10 person-years before the index date and 2.27 relapses per 10 person-years following the index date [rate ratio (95% CI); 0.66 (0.45, 0.99). Although both groups had a reduction in relapse rate ratios, the rate of decrease in relapse rate was significantly greater in patients on MTX than those not on MTX (p=0.002) [Figure]. Patients receiving MTX discontinued GC significantly later than patients without adjuvant MTX (p=0.014).

Conclusion: In this large single-institution cohort, the addition of MTX to GC decreased the rate of subsequent relapse by 2-fold compared to patients on GC alone. MTX should be considered as adjunct therapy in patients with relapsing GCA to decrease the risk of further relapse events.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/efficacy-of-methotrexate-in-giant-cell-arteritis/