POS0972 CLUSTER ANALYSIS OF ANKYLOSING SPONDYLITIS PATIENTS REVEALS DIFFERENTIAL DRUG SURVIVAL OF ANTI-TNF AGENTS ACCORDING TO DISTINCT CLINICAL PHENOTYPE
Authors: S. Lee, S. Y. Kang, Y. H. Eun, H. Kim, H. S. Cha, E. M. Koh, J. Lee
Journal: Annals of the Rheumatic Diseases (2021)

Background: Previous studies using cluster analysis technique in ankylosing spondylitis (AS) patients have consistently identified distinct groups of patients in terms of their clinical characteristics: those with pure axial symptoms and those with a high frequency of peripheral manifestations [1,2]. Due to the cross-sectional nature of these studies, however, prognostic information such as drug survival of anti-TNF agents in these group were not provided. Objectives: Using the data retrieved from Korean College of Rheumatology Biologics (KOBIO) registry, which includes longitudinal data of AS patients using anti-TNF agents, this study aims to perform cluster analysis to differentiate AS patients in terms of clinical phenotypes and to examine the differential drug survival of anti-TNF agents in these groups. Methods: Clinical characteristics and demographic data of AS patients in KOBIO registry were analyzed using hierarchical clustering analysis. After clustering, drug survivals of anti-TNF agents were compared between these groups. Results: 1,046 patients were included in the study with no missing data. The hierarchical cluster analysis classified patients in two groups; one with predominant isolated axial manifestations (axial group, n=823) and the other with more frequent extra-axial symptoms (extra-axial group, n=223). Almost all extra-axial symptoms (peripheral arthritis, enthesitis, uveitis, dactylitis, and psoriasis) were more frequently observed in extra-axial group than axial group. In addition, patients with shorter disease duration, late disease onset, and high disease activity were classified in extra-axial group (Table 1). Interestingly, the extra-axial group had lower drug survival probability than the axial group (p=0.008, Figure 1). Conclusion: Cluster analysis of AS patients using anti-TNF agents classified two distinct groups of patients in terms of their clinical phenotypes and revealed that the patients with prominent extra-axial manifestations had lower drug survival with anti-TNF agents. References: [1]Costantino F, et al. Two Phenotypes Are Identified by Cluster Analysis in Early Inflammatory Back Pain Suggestive of Spondyloarthritis: Results From the DESIR Cohort. Arthritis Rheumatol. 2016 Jul;68(7):1660-8. [2]Porcher R, et al. Two major spondylarthropathy phenotypes are distinguished by pattern analysis in multiplex families. Arthritis Rheum. 2005 Apr 15;53(2):263-71. Table 1. Clinical characteristics of divided groups Group 1 (axial group) 2 (extra-axial group) p Number of patients 823 223 Age at start of TNFi (yr) 38.21 (12.78) 38.58 (14.17) 0.713 Disease duration (yr) 3.95 (5.26) 2.29 (4.32) &lt;0.001 Age at diagnosis 34.27 (13.05) 36.29 (14.11) 0.044 Sex (male) (%) 645 (78.4) 152 (68.2) 0.002 HLA-B27 positivity (%) 736 (89.4) 197 (88.3) 0.732 Inflammatory back pain (%) 699 (84.9) 191 (85.7) 0.872 Peripheral arthritis (%) 201 (24.4) 191 (85.7) &lt;0.001 Enthesitis (%) 65 (7.9) 154 (69.1) &lt;0.001 Uveitis (%) 163 (19.8) 59 (26.5) 0.039 Dactylitis (%) 12 (1.5) 13 (5.8) &lt;0.001 Psoriasis (%) 15 (1.8) 12 (5.4) 0.006 Good response to NSAIDs (%) 205 (24.9) 155 (69.5) &lt;0.001 Family history (%) 88 (10.7) 27 (12.1) 0.632 Smoking (%) 408 (49.6) 102 (45.7) 0.347 CRP (mg/dl) 2.10 (2.74) 2.89 (3.57) &lt;0.001 ESR (mm/hr) 35.52 (28.73) 46.33 (32.94) &lt;0.001 BASDAI 5.93 (1.92) 6.41 (1.80) 0.001 BASF 3.42 (2.56) 3.64 (2.58) 0.255 Drug change after one year (%) 160 (19.4) 61 (27.4) 0.013 Disclosure of Interests: None declared.