SAT0381 UNDERSTANDING JOINT REPLACEMENT SURGERY IN AXIAL SPONDYLOARTHROPATHY
Authors: S. Maguire, P. Gallagher, F. B. O’shea
Journal: Annals of the Rheumatic Diseases (2020)

Background: Axial spondyloarthropathy(axSpA) is a form of inflammatory arthritis that primarily affects the axial skeleton and sacroiliac joint, but can be associated with a peripheral arthritis. Rapid advances in the field of axSpA has led to faster detection, diagnosis and treatment of this disease. This improved management has led to improved level of function and quality of life for patients, despite this a proportion of patients are still requiring joint replacement surgery. The Ankylosing Spondylitis Registry of Ireland (ASRI) is a source of epidemiological data on patients with axSpA in Ireland. Given the large size of the ASRI to date, this is a prime opportunity to analyze patients with axSpA requiring joint replacement surgery. Objectives: Detailed analysis of a large cohort of patients with axSpA with a focus on those who underwent joint replacement to determine trends in disease and baseline demographics. Methods: The patient population registered in the ASRI was analysed using IBM SPSS version 26. Analysis was performed by comparing patients who underwent joint replacement surgery to the rest of the ASRI cohort. Mean age, disease duration, delay to diagnosis and scores of disease activity (BASDAI, BASFI, HAQ, ASQoL and BASMI) were compared between these two groups. Differences between the groups was tested for significance using an independent two tailed t-test. Further analysis on gender, HLA-B27 status, co-morbidities and medication exposure was done using a chi-squared test for independence. A p value of less than 0.05 was deemed significant. Results: At present 860 patients are currently enrolled in the ASRI with 76.6% (659) males and 23.4% (201) females. Average age of patients is 45.8 years, mean disease duration of 19.4 years with 95.5% (821) of patients listed as Caucasian. Mean scores were BASDAI 4.02, BASFI 3.7, BASMI4.02, HAQ 0.55, and ASQoL of 6.51. In total 33 (3.8%) of patients underwent joint replacement surgery. These patients were noted to be significantly older than the rest of the rest of the cohort (55.3 years old vs 45.1, p&lt;0.01), with a longer disease duration (31.6 years vs 18.3, p&lt;0.01) and higher rates of HLA-B27 positivity (94.7% vs 80.2%, p&lt;0.01). No significant differences were noted between gender(table 1). No significant difference was found between medication exposure rates, although the joint replacement population did have higher rates of NSAID, sDMARD and biologic therapy usage than the rest of the population although this did not reach significance. These patients also scored worse in all measures of disease activity, although this only reached significance in the BASFI (5.67 vs 3.64, p&lt;0.01), HAQ (0.9 vs 0.54, p&lt;0.01) and the BASMI (6.07 vs 3.94, p&lt;0.01). Table 1. Joint replacement (n=33 ) No Joint Replacement (n=827 ) p value Age 55.3 45.1 &lt;0.01 Disease duration 31.6 18.31 &lt;0.01 Delay to dx 6.97 7.97 0.51 HLA-B27+ 94.7% (18) 71.9% (491) &lt;0.01 Males 78.8% (26) 64.7% (535) 0.76 Females 21.2% (7) 19.3% (160) 0.76 Mean Scores BASDAI 4.91 4.06 0.06 BASFI 5.67 3.64 &lt;0.01 HAQ 0.9 0.54 &lt;0.01 ASQoL 7.42 6.67 0.45 BASMI 6.07 3.94 &lt;0.01 Medications NSAIDs 51.5% (17) 47% (389) 0.21 Bio tx 72.7% (24) 57.2% (473) 0.9 DMARDs 33.3% (11) 15.7% (130) 0.1 Conclusion: Patients requiring joint replacement surgery, although few in number, represent a cohort with significantly impaired function and quality of life. This is likely due to the fact that these patients were older with more established disease. It is therefore not surprising that this cohort had significantly worse spinal mobility. As registries continues to develop, it will be interesting to see if rates of joint replacement surgery will decline with increased use of biologic therapy at an earlier stage of disease. This will help to differentiate patients requiring joint replacement surgery due to underlying inflammatory arthritis and those with osteoarthritis. Disclosure of Interests: Sinead Maguire Grant/research support from: ASRI is supported by funding from Pfizer, AbbVie and UCB, Phil Gallagher: None declared, Finbar Barry O’Shea Grant/research support from: ASRI is supported by funding from Pfizer, AbbVie and UCB