Background Giant cell arteritis (GCA) is the most common systemic vasculitis and patients with GCA frequently experience one or more relapses during treatment. In order to address differential lengths of followup, relapse rates provide a novel method to evaluate patients with GCA at risk for more frequent relapses.
Objectives To evaluate the relapse rates, characteristics, predisposing factors, and relationship with mortality in a large single-institution cohort of patients with biopsy-proven GCA.
Methods A retrospective review was performed to identify all patients with biopsy-proven GCA from 1 January 1998 through 31 December 2013. Demographic, clinical, and laboratory data at presentation and each follow up visit were collected. Relapse was defined as recurrence of clinical manifestations compatible with spectrum of GCA and/or increase in inflammatory markers (ESR/CRP), not otherwise explainable, which required reintroduction or increased dose of glucocorticoid therapy. Comparisons between relapse and no-relapse groups were performed using Chi-square and Kruskal-Wallis tests.
Results The cohort included 286 patients with biopsy-proven GCA (213 females and 73 males, mean [±SD] age 75.0 [±7.6] years) with a mean (±SD) follow-up of 6.0 (±3.9) years. The mean (±SD) number of visits was 14.2 (±8.4) and the mean (±SD) visit rate per person per year was 3.3 (±2.6). During follow-up, 73 patients did not have a relapse, 80 patients had one relapse and 133 had two or more relapses. The first relapse occurred during the first year in 50% of patients (by 2 years in 68% and by 5 years in 79%). Among all relapse visits, 28.6% of relapses were related to abnormal lab markers only, 24.2% were related to flare symptoms only, and 47.2% represented flare symptoms and abnormal lab markers. The most common relapse symptoms were polymyalgia rheumatica (33.1%), headache (32.3%), malaise (20.6%) and scalp tenderness (7.8%).
The median relapse rate observed was 0.4 [IQR 0.21, 0.64] relapses per year. We further evaluated patients in three groups; no relapse, low relapse rate (<0.5 relapses/yr), and high relapse rate (≥0.5 relapses/yr). A lower proportion of females were in the no relapse group (63%) than in the <0.5 relapses/yr (79%) or the ≥0.5 relapses/yr (78%) groups (p=0.034). A higher proportion of patients with hypertension (p=0.007), diabetes (p=0.039) and prior history of venous thrombosis (p=0.041) were present in the ≥0.5 relapse/yr group compared to the no relapse and <0.5 relapse/yr groups. In this cohort, neither the presence of relapse [HR 0.80, (0.47, 1.36); p=0.41] nor the number of relapses [HR 0.99 (0.83, 1.19); p=0.94] were associated with excess mortality.
Conclusions Patients with biopsy-proven GCA have a high risk of relapse during follow up. Women with GCA tend to relapse more than men. Patients with established hypertension or diabetes at time of GCA diagnosis have a higher frequency of relapse. Relapses were not predictive of higher mortality.
Disclosure of Interest None declared