AB0178 PERIARTICULAR OSTEOPHYTE FORMATION PROTECTS AGAINST TOTAL KNEE ARTHROPLASTY IN RHEUMATOID ARTHRITIS PATIENTS WITH ADVANCED JOINT DAMAGE
Authors: S. Asai, N. Takahashi, K. Terabe, T. Kojima, N. Ishiguro
Journal: Annals of the Rheumatic Diseases (2020)

Background: New medications including biologics and aggressive treatment strategies can halt the inflammatory and destructive disease processes in patients with rheumatoid arthritis (RA), and in some cases repair damaged joints. In the process of damaged joint repair, periarticular osteophyte formation might be detected radiographically (1). However, little is known about the clinical and functional role of osteophyte formation in RA joints. Total joint arthroplasty, a common procedure for treating damaged large joints, can serve as a surrogate for the long-term outcome of large joint destruction in patients with RA. Objectives: To determine the influence of periarticular osteophyte formation on the incidence of total knee arthroplasty (TKA) in patients with RA. Methods: This retrospective longitudinal study used data from a registry of patients with RA starting biologics. A flow chart summarizing the study design is shown in Figure 1. A total of 130 symptomatic (tender and/or swollen) knee joints in 80 patients were studied with a median follow-up of 12 years. All data were analyzed using the knee joint as the statistical unit of analysis. The cumulative incidences of TKA were estimated using Kaplan-Meier curves, and compared according to the presence or absence of osteophyte on plain anteroposterior radiograph [osteophyte (+/-)] and the extent of advanced joint damage as defined by Larsen’s grading system (0-II vs. III-V). Results: Baseline characteristics of all subjects included in this study are shown in Table 1. A total of 42 knees underwent TKA during the follow-up period. There was no significant difference in the cumulative incidence of TKA between the osteophyte (+) and osteophyte (-) groups (31% vs. 34% at 10 years, P=0.718) (Fig. 2A). The cumulative incidence of TKA was significantly higher for the Larsen grade III-V group compared to the Larsen grade 0-II group (56% vs. 10% at 10 years, P&lt;0.001) (Fig. 2B). While no significant difference was observed in the cumulative incidence of TKA between the osteophyte (+) and osteophyte (-) groups in the Larsen grade 0-II group (9% vs. 10% at 10 years, P=0.774) (Fig. 2C), the cumulative incidence of TKA was significantly lower for the osteophyte (+) group compared to the osteophyte (-) group in the Larsen grade III-V group (38% vs. 74% at 10 years, P=0.010) (Fig. 2D). Multivariate analysis using Cox proportional hazards models revealed that older age [hazard ratio (HR): 1.04 per 1 year, 95% confidence interval (CI): 1.01-1.08] and osteophyte formation (HR: 0.39, 95% CI: 0.19-0.79) independently predicted TKA in the Larsen grade III-V group, whereas none of the assessed variables predicted TKA in the Larsen grade 0-II group. Table 1. Baseline characteristics by presence or absence of osteophyte formation Total Osteophyte (+) Osteophyte (-) Characteristics n = 130 n = 44 n = 86 P value Age, years 57 (41-63) 59 (52-65) 56 (39-63) 0.051 Sex, female, n (%) 108 (83) 40 (91) 68 (80) 0.137 Body mass index 21.3 (19.0-23.8) 21.3 (18.9-24.4) 21.2 (19.0-23.7) 0.744 Disease duration, years 8 (3-12) 9 (5-18) 7 (3-11) 0.007 Larsen grade, n (%) &lt;0.001 Grade 0-II 66 (51) 11 (25) 55 (64) Grade III-V 64 (59) 33 (75) 31 (36) Osteophyte formation, n (%) 44 (34) - - - RF or ACPA positive, n (%) 85 (83) 35 (90) 50 (78) 0.183 CRP, mg/dl 3.2 (1.5-4.9) 2.9 (1.0-4.1) 3.4 (1.8-5.2) 0.172 First biologic agent, n (%) 1.000 Infliximab 57 (44) 19 (43) 38 (44) Etanercept 73 (56) 25 (57) 48 (56) Use of methotrexate, n (%) 98 (75) 33 (75) 65 (76) 1.000 Methotrexate dose, mg/week* 8 (6-10) 8 (6-9) 8 (6-10) 0.104 Use of glucocorticoids, n (%) 79 (61) 22 (50) 57 (66) 0.088 Glucocorticoid dose, mg/day*† 5.0 (5.0-7.5) 5.0 (5.0-5.0) 5.0 (5.0-7.8) 0.204 Data are presented as median (interquartile range) or number of subjects (percentages). *Median among subjects receiving the drug. †Prednisolone equivalent (mg/day). Conclusion: Osteophyte formation reduces the incidence of TKA in patients with RA who have advanced joint damage. References: [1]Rau R. Clin Exp Rheumatol 2006;24:S-41-4. Disclosure of Interests: Shuji Asai Speakers bureau: AbbVie, Astellas, Bristol-Myers Squibb, Chugai, Daiichi-Sankyo, Eisai, Janssen, Takeda, and UCB Japan, Nobunori Takahashi Speakers bureau: AbbVie, Asahi Kasei, Astellas, Bristol-Myers Squibb, Chugai, Daiichi-Sankyo, Eisai, Eli Lilly, Janssen, Mitsubishi Tanabe, Ono, Pfizer, Takeda, and UCB Japan, KENYA TERABE: None declared, Toshihisa Kojima Grant/research support from: Chugai, Eli Lilly, Astellas, Abbvie, and Novartis, Consultant of: AbbVie, Speakers bureau: AbbVie, Astellas, Bristol-Myers Squibb, Chugai, Daiichi-Sankyo, Eli Lilly, Janssen, Mitsubishi Tanabe, Pfizer, and Takeda, Naoki Ishiguro Grant/research support from: AbbVie, Asahi Kasei, Astellas, Chugai, Daiichi-Sankyo, Eisai, Kaken, Mitsubishi Tanabe, Otsuka, Pfizer, Takeda, and Zimmer Biomet, Consultant of: Ono, Speakers bureau: Astellas, Bristol-Myers Squibb, Daiichi-Sankyo, Eli Lilly, Pfizer, and Taisho Toyama