46. Seasonal incidence of giant cell arteritis or polymyalgia rheumatica
Creators: name: Sattui1, Sebastian
name: Putman2, Michael
Publisher: name: Zenodo
Year: 2022
Subjects: Vasculitis
ANCA
Abstracts
Giant Cell Arthritis
MPA
GPA
EGPA
Takayasu
IgA vasculitis

description: <strong><em>Background</em></strong><em>:</em> Prior studies have observed a seasonal pattern in the incidence of both polymyalgia rheumatica (PMR) and giant cell arteritis (GCA), but neither finding has been consistently replicated in larger cohort studies or meta-analyses. The objective of this study was to describe seasonal patterns among incident cases of GCA and PMR. <strong>Methods: </strong>A retrospective cohort study was conducted using data from the TriNetX (Cambridge, MA, USA) electronic health records database, which includes records from multiple United States health organizations. Patients with GCA were identified using validated case-finding algorithms (PPV 79%), which required (1) 2 encounters with GCA diagnostic codes (ICD-9-CM 446.5/ICD-10 M31.6 or M31.5) that occurred at least 30 days apart and (2) at least one moderate-high dose prednisone prescription (greater than or equal to 20mg/day of prednisone or one dose of 500mg or greater intravenous methylprednisolone). Patients with PMR were identified using 2 encounters with a PMR diagnostic code (ICD-9-CM 725/ICD-10 M35.3) at least 30 days apart, any dose of prednisone, and not meeting the criteria for GCA. The index date was defined as the first date of moderate-high dose prednisone for GCA and the first date of any prednisone prescription for PMR. Patients who were under 50 years of age or had less than 1 year of follow up prior to the index date were excluded. The incident rate ratio (IRR) was calculated using unconditional maximum likelihood estimations and confidence intervals were calculated using Wald normal approximation intervals. <strong>Results:</strong> We identified 1,129 cases of GCA and 17,023 incident cases of PMR who were followed for 149,005 patient-years prior to their index date of diagnosis. The mean age for incident cases of GCA was 73.9 years (SD 8.1) and the mean age for PMR was 72.3 (SD 8.5). Most patients were female (69%% GCA, 59% PMR) and reported white (79% GCA, 85% PMR) or black (10% GCA, 6% PMR) race/ethnicity. There were no significant differences in the incidence rate ratio of GCA diagnoses as compared to January-March for April-June (IRR 0.99, 95% confidence interval (CI) 0.84-1.17), July-September (IRR 1.06, CI 0.90-1.25), or October-December (IRR 1.01, CI 0.85-1.19) (Figure 1A). There were also no significant differences in the incidence rate ratio of PMR diagnoses as compared to January-March for April-June (IRR 1.00, 95% confidence interval (CI) 0.), July-0.96-1.05, September (IRR 1.00, CI 0.), or O0.96-1.05, or October-December (IRR 0.96, CI 0.92-1.00) (Figure 1A). <strong>Conclusions:</strong> In this large analysis of an electronic health records database, there were no seasonal patterns in the diagnosis of GCA or PMR. These results do not support the existence of a seasonal pattern in diagnosis for either disease but require validation in a better-characterized cohort. <strong>Disclosure:</strong> Sebastian Sattui receives research funding related to clinical trials by AstraZeneca (MANDARA). Michael Putman receives research funding related to clinical trials by Abbvie (SELECT-GCA) and AstraZeneca (MANDARA).