FRI0186 JOINT INVOLVEMENT AND DISEASE ACTIVITY IN SYSTEMIC LUPUS ERYTHEMATOSUS PATIENTS: CALCULATION OF SWOLLEN TO TENDER JOINT COUNT RATIO IN A REAL WORLD COHORT IN THE US
Authors: C. Cavanaugh, G. Donadio, K. Starzyk, M. Behling, G. Curhan, R. Gliklich
Journal: Annals of the Rheumatic Diseases (2020)

Background: Joint swelling and tenderness are common in patients with systemic lupus erythematosus (SLE). Swollen to tender joint count ratio (STR) is an index originally used in rheumatoid arthritis (RA) which assesses severity of disease activity based on 28 joint counts [1]. In RA, STR is a predictor of treatment response with a higher score indicating greater likelihood of responding. Objectives: To characterize SLE patients in a real-world cohort based on disease activity as defined by STR. Methods: The OM1 SLE Registry (OM1, Boston, MA) follows more than 37,000 SLE patients longitudinally with deep clinical data, including laboratory, patient-reported and disease activity information, and linked administrative claims, starting from 2013. Patients ≥16 years of age with swollen and tender joint counts based on 28 joints on the same encounter were included. STRs were calculated by inserting 1 if the denominator was 0 [2]. Patients were categorized by first available STR as having low (STR &lt;0.5), moderate (0.5 ≤ STR ≤ 1.0), and high (STR &gt;1.0) disease activity. Clinical characteristics were summarized by disease activity group. Definitions of SLE treatments were based on 2019 EULAR recommendations [3]. Results: As of December 2019, there were 9,919 patients with at least one STR available in the OM1 SLE Registry. STR was low in 80.4%, moderate in 12.2%, and high in 7.4% of patients. Mean age overall was 52.1 years (standard deviation: 14.8), 92.1% were female, and 71.8% of 7,730 patients with known race were white. Clinical characteristics by STR group are described in Table 1. Antimalarial use decreased and immunosuppressant use increased with increasing STR. Use of select disease-modifying antirheumatic drugs (DMARDs) was higher among patients with moderate or high STR. Lupus nephritis was more common in patients with low STR. A higher proportion of patients with moderate STR had osteoarthritis. The proportion of patients with anxiety and depression decreased with increasing STR. On average, patient and physician global assessments from MDHAQ were higher for patients with moderate STR. Table 1. Clinical characteristics of patients with SLE by swollen:tender joint count ratio group Low STR &lt;0.5 (N=7,970) Moderate 0.5 ≤ STR ≤ 1.0 (N=1,211) High STR &gt;1.0 (N=738) Treatment prior to STR, n (%) Antimalarial 5,106 (64.1%) 702 (58.0%) 427 (57.9%) Biologics (belimumab or rituximab) 662 (8.3%) 113 (9.3%) 70 (9.5%) Immunosuppressants 2,310 (29.0%) 398 (32.9%) 252 (34.1%) Select DMARDs 635 (8.0%) 165 (13.6%) 94 (12.7%) Steroids 4,437 (55.7%) 785 (64.8%) 434 (58.8%) Disease conditions prior to STR, n (%) Anxiety 266 (3.3%) 25 (2.1%) 12 (1.6%) Depression 1,127 (14.1%) 149 (12.3%) 80 (10.8%) Lupus nephritis 984 (12.3%) 117 (9.7%) 72 (9.8%) Osteoarthritis 2,336 (29.3%) 393 (32.5%) 193 (26.2%) Osteoporosis 631 (7.9%) 95 (7.8%) 47 (6.4%) MDHAQ, N 1,991 388 230 MDHAQ, mean (SD) Patient global assessment (0-10) 4.5 (2.9) 5.3 (2.7) 4.4 (2.8) Physician global assessment (0-10) 2.8 (2.7) 3.8 (2.6) 2.8 (2.3) Conclusion: Differences in treatments received were apparent between patients of varying disease activity groups with trends towards increased use among patients with higher disease activity. Additional research is needed to determine the utility of this measure for assessing SLE-related outcomes. References: [1]Cipriano et al., Reumatismo 2015 Sept 16;67(2):62-7 [2]Hammer HB et al., Arthritis Rheumatol 2016; 68 (suppl 10) [3]Fanouriakis et al., Ann Rheum Dis. 2019;78:736-745 Disclosure of Interests: None declared