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We aimed to examine a) the policies of national and international clinical trial registries regarding observational studies; b) the time trends of observational study registration; and c) the published arguments for and against observational study registration. Scoping review of registry practices and published arguments. We searched the websites and databases of all 19 members of the World Health Organization's Registry Network to identify policies relating to observational studies and the number of observational studies registered annually from the beginning of the registries to 2022. Regarding documents with arguments, we searched Medline, Embase, Google Scholar, and top medical and epidemiological journals from 2009 to 2023. We classified arguments as “main” based on the number (n ≥ 3) of documents they occurred in. Of 19 registries, 15 allowed observational study registration, of which seven (35%) had an explicit policy regarding what to register and two (11%) about when to register. The annual number of observational study registrations increased over time in all registries; for example, ClinicalTrials.gov increased from 313 in 1999 to 9775 in 2022. Fifty documents provided arguments concerning observational study registration: 31 argued for, 18 against, and one was neutral. Since 2012, 19 out of 25 documents argued for. We classified nine arguments as main: five for and four against. The two most prevalent arguments for were the prevention of selective reporting of outcomes (n = 16) and publication bias (n = 12), and against were that it will hinder exploration of new ideas (n = 17) and it will waste resources (n = 6). Few registries have policies regarding observational studies; an increasing number of observational studies were registered; there was a lively debate on the merits of registration of observational studies, which, since 2012, seems to converge toward proregistration. •Only 7 (35%) study registries had an explicit policy for observational studies.•Only 2 (11%) registries specified when to register observational studies.•The annual number of observational study registration increased in all registries.•The debate on observational study registration converges toward pro-registration.

Background:In patients with Sjögren’s Syndrome (SS), the biopsy of minor salivary glands (MSG) is a fundamental diagnostic and prognostic tool. However, there is still variability in the histological parameters considered, and the clinical/laboratory associations are yet to be clarified.Objectives:Aim of this study is to investigate in a large monocentric cohort of primary SS patients (Sjogren Clinic at University of Rome Sapienza), the predictive value of MSG histology versus the main clinical, clinimetric and laboratory features.Methods:Primary SS patients undergoing MSG biopsy between 2016 and 2023 were retrospectively enrolled and the histological/clinical/clinimetric/laboratory data were collected. Histological analysis comprised: focus score (FS) and n° of foci calculation, germinal centers (GCs) [nodular aggregates (H&E), confirmed by CD21+ or Bcl6+ (IHC)] and lymphoepithelial lesions (LEL) (CD20+ IHC in ducts) detection and fibrosis (H&E) recognition. Logistic and linear regression analyses were performed to evaluate the predictive value of histology on clinical/clinimetric/laboratory parameters.Results:Two-hundred and thirty-two SS patients were enrolled [mean age 53.6 years (±13.6), F=223/M=9] (figure 1). Both the FS and the n° of foci were predictive of anti-La/SSB, RF, hypergammaglobulinemia and were positively correlated with the ESSDAI. Wile the FS was predictive for low C4 levels, the n° of foci was predictive for anti-Ro/SSA, monoclonal component, biologic and glandular ESSDAI domains. As we recently published [1], a lower FS and n° of foci was predictive for the presence of autoimmune thyroiditis. We found a large agreement between CD21+ and Bcl6+ staining. The presence of GCs (either CD21+ or Bcl6+) was predictive for those serological features associated with a more severe disease. GCs were also predictive of specific ESSDAI domains linked with higher risk of lymphoproliferative complications (Figure 1). Both the CD21+ and the Bcl6+ stainings were predictive of an higher ESSDAI score. Compared to GCs, LEL were even more predictive of different serological features and ESSDAI domains (Figure 1). Interestingly, the presence of fibrosis was associated with a lack of anti-Ro/SSA-La/SSB antibodies. Three patients developed MALT lymphoma; all of them had GCs (CD21+/Bcl6+) and LEL in their MSG biopsies, none had fibrosis [n° of foci: mean=8.3 (SD:5-13); FS mean=3.6 (SD=2.12-4.88)].Conclusion:This is one of the largest studies evaluating the predictive value of histology versus different clinical, clinimetric and laboratory parameters of patients with primary SS. Our data confirm the association between a higher FS and the presence of both serological features known to be linked to a more severe disease and higher ESSDAI score values. Compared to the FS, the number of foci revealed additional associations such as the biological and glandular ESSDAI domains. We confirm the association between GCs and those serological/clinical features accompanying a more systemic and active disease and we provide evidence of the same, and also additional associations, for the LEL. Finally, we demonstrate for the first time that the presence of fibrosis may be predictive of seronegative patients; this relevant finding, is currently under validation on a larger cohort.REFERENCES:[1] Colafrancesco S, et al. Clinical and histological features of patients with primary Sjögren’s syndrome and autoimmune thyroiditis: a national multicentre cross-sectional study. Clin Exp Rheumatol. 2023;41(12):2389-2396.Acknowledgements:NIL.Disclosure of Interests:None declared.

Background:Gout is the most common inflammatory arthritis caused by hyperuricemia. And the incidence of juvenile gout was rising worldwide. The specific mechanisms and treatment strategies remain unclear. Febuxostat is commonly used to lower blood uric acid levels in adult gout patients, but its efficacy in juvenile gout patients with different genetic backgrounds has not been adequately studied. Numerous prior studies have indicated that the T allele genotype at the C677T site of the MTHFR gene increases hyperuricemia risk by elevating plasma homocysteine levels. Similarly, the ABCG2 gene, implicated in gout susceptibility, affects uric acid levels through the regulation of renal excretion and reabsorption.Objectives:This study aims to investigate the relationship between variations of MTHFR and ABCG2 gene and both the gout onset in children and the efficacy of Febuxostat.Methods:These studies were approved by theInstitutional Review Board of Guangdong Second provincial General Hospital.The study enrolled 31 pediatric gout patients, 18 of whom received Febuxostat treatment regularly(40mg per day) for 12 weeks, alongside 16 non-gout children (aged 10 to 18 years, male). EDTA whole blood samples were collected for genetic testing of the ABCG2 gene c.421C>A (rs2231142) and the MTHFR gene c.677C>T (rs1801133). Participants were categorized based on these gene sites into three groups: homozygous defect (AA), heterozygous defect (CA), and full-function (CC) for ABCG2; and similarly for MTHFR. Treatment efficacy was determined based on blood uric acid levels, with levels exceeding 420 μmol/L classified as a “poor response” and levels at or below 420 μmol/L as a “good response.” The Chi-square test was employed for statistical analysis.Results:Significant differences were observed in ABCG2 (rs2231142) between juvenile gout and non-gout group (p=0.0043), but no correlation was noted in the response to Febuxostat treatment (Table 1). The juvenile gout group contained 10 cases in the homozygous defect group (AA), 17 in the heterozygous defect group (CA), and 4 in the full-function group (CC). In contrast, the non-gout group had 0, 8, and 8 cases, respectively. A statistically significant difference was found in MTHFR (rs1801133) between groups with varying responses to Febuxostat treatment (p=0.035), with a higher proportion of CT and CC genotypes in the good response group (Table 2). However, no statistical difference was noted in ABCG2 (A) rs2231142 between the two Febuxostat treatment groups.Conclusion:Our results showed that ABCG2 genotyping played an important role in the risk of gout in juvenile. When predicting or evaluating the efficacy of febuxostat, MTHFR genotyping may have a certain guiding role in the selection of research plans.REFERENCES:[1] Ciferska, H, Pavelcova, K, Vachek, J, et al. POS0354 DETECTION OF ABCG2 VARIANTS IN ENCODING OF uric acid TRANSPORTERS ASSOCIATED WITH THE HYPERURICEMIA IN HAEMODIALYSIS PATIENTS ANN RHEUM DIS. 2021; 80 (Suppl 1): 407.2-408. doi: 10.1136/annrheumdis-2021-eular.2084.[2] van der Pol, KH, Nijenhuis, M, Soree, B, et al. Dutch pharmacogenetics working group guideline for the gene-drug interaction of ABCG2, HLA-B and Allopurinol, and MTHFR, folic acid and methotrexate. EUR J HUM GENET. 2022; doi: 10.1038/s41431-022-01180-0.Acknowledgements:This study was supported by Medical Scientific Research Foundation of Guangdong Province(B2022162, A2023045).Disclosure of Interests:None declared.

Background:Osteoporosis is defined as a bone mineral density (BMD) of at least 2.5 standard deviations below the young adult mean (YAM) (T-score ≤2.5) according to World Health Organization criteria, or a BMD of 70% or lower than YAM (YAM% ≤70) according to the Japanese Society for Bone and Mineral Research (JSBMR)criteria. The primary aim of osteoporosis treatment is to decrease fracture incidences; however, untreated cases may persist due to undiagnosed osteoporosis. In our 2019 report, we found that 38% of menopausal patients diagnosed with osteoporosis solely at the distal radius, without prior fracture surgery, did not exhibit osteoporosis at either the hip or lumbar spine. Moreover, the decrease in YAM% occurred significantly earlier than that observed in the hip and lumbar spine. These findings suggest that relying solely on BMD measurements at the hip and lubar spine may be insufficient for diagnosing osteoporosis. The present study aimed to investigate the correlations of BMD among three skeletal sites in female patients undergoing surgery for proximal femur fracture (PFF) or distal radius fracture (DRF) and assess the necessity of measuring BMD at the distal radius.Objectives:We enrolled 116 PFF female patients (mean age 81.1) and 47 DRF female patients (mean age 71.2) who underwent surgery between 2021 and 2023.Methods:BMDs of the distal radius, hip, and lumbar spine were measured by dual energy X-ray absorptiometry (Prodigy, GE Healthcare UK Ltd.). The cut-off values for the diagnosis of osteoporosis according to JSBMR criteria were used. Correlations between BMDs of skeletal sites (distal radius and hip, distal radius and lumbar spine, and hip and lumbar spine) were assessed using t-test.Results:In PFF patients, YAM% of the distal radius (57.7%) was significantly lower than that of the hip (61.9%, P < 0.019) and lumbar spine (68.9%, p < 0.001). Correlation coefficients of BMD between the distal radius and hip, distal radius and lumbar spine, and hip and lumbar spine were 0.50001, 0.46403, and 0.52521, respectively.In DRF patients, YAM% of the distal radius (70.1%) was lower than that of the hip (75.1%, P < 0.045) and lumbar spine (76%, P < 0.020). Correlation coefficients of BMD between the distal radius and hip, distal radius and lumbar spine, and hip and lumbar spine were 0.55303, 0.36069, and 0.44750, respectively. Among the 90 PFF patients diagnosed as osteoporotic at the distal radius, 13 (14.4%) were not osteoporotic at either the lumbar spine or hip, 3 (3.3%) were osteoporotic at the hip but not lumbar spine, 21 (23.3%) were osteoporotic at the lumbar spine but not hip, and 53 (59.0%) were osteoporotic at both the lumbar spine and hip. Among the 27 DRF patients diagnosed as osteoporotic at the distal radius, 10 (37.1%) were not osteoporotic at either the lumbar spine or hip, six (22.2%) were osteoporotic at the hip but not lumbar spine, six (22.2%) were osteoporotic at the lumbar spine but not hip, and five (18.5%) were osteoporotic at both the hip and lumbar spine.Conclusion:Among DRF patients with distal radius YAM% lower than 70%, 38.5% of patients had both hip and lumbar spine YAM% of 70% or > 70%, which was higher than that of PFF patients. Our findings suggest that there was a period of earlier decline in BMD of the distal radius in fracture patients than in the hip and lumbar spine, which may have led to DRF. Sakai et al. reported that 58% of Colles’ fracture patients had lumbar spine YAM% of 70% or higher. Furthermore, the patients in this study who developed DRF with a distal radius YAM% < 70% were not diagnosed with osteoporosis and did not receive any therapeutic intervention. Thus, measuring the BMD of the distal radius is essential to avoid underestimating the actual value of BMD for the diagnosis of osteoporosis.REFERENCES:[1] Nakaseko K. Bone Mineral Density of the Spine, Hip, and Distal Radius in Patients with Postmenopausal Osteoporosis. Arthritis & Rheumatology 2019; 71: 3901-3903.[2] Sakai A, et al. Association of bone mineral density with deformity of the distal radius in low-energy Colles’ fractures in Japanese women above 50 years of age. J Hand Surg Am 2008; 33(6): 820-826.Acknowledgements:NIL.Disclosure of Interests:None declared.

Background:It remains uncertain whether the concept of a “window of opportunity”, as defined for rheumatoid arthritis, applies to axial spondyloarthritis (axSpA). The Assessment in SpondyloArthritis international Society (ASAS) has published a consensus definition for “early” axSpA, which relies on axial symptom duration of ≤2 years [1]. Recent research using this definition has indicated that the effectiveness of treatment with tumor necrosis factor inhibitors (TNFi) is comparable in early and established disease [2]. To further explore the potential for improved outcomes in patients diagnosed and treated at an earlier stage, we here evaluate a shorter cut-off for the definition of early axial symptom duration.Objectives:To analyze the effectiveness of treatment with a first TNFi in patients with “very early” axSpA, defined as an axial symptom duration ≤1 year, in comparison to patients with established axSpA (axial symptom duration >2 years).Methods:Patients from a large national observational cohort of patients diagnosed as having axSpA were included in the current study if data on duration of axial symptoms was available and a first TNFi initiated between 2004 and 2023. Patients were stratified according to axial symptom duration: very early axSpA (≤1 year), early axSpA (>1 year and ≤2 years), and established axSpA (≥2 years). Drug retention was analyzed using Cox proportional hazards models, adjusting for age, sex, human leucocyte antigen B27 (HLA-B27) positivity, body mass index (BMI), education, smoking status, elevated C-reactive protein (CRP), and inflammation on magnetic resonance imaging (MRI) of the sacroiliac joints in patients with complete covariate information. Adjusted logistic regression analyses were employed to determine the achievement of the Bath Ankylosing Spondylitis Disease Activity Index criteria for 50% improvement (BASDAI50) at 12±6 months (intention-to-treat analyses in patients with available visits).Results:A total of 1080 patients met the inclusion criteria, with 131 in the very early axSpA group (12.1%), 75 in the early axSpA group (6.9%) and 874 in the established axSpA group. Characteristics of patients at the initiation of the first TNFi are presented in Table 1. Patients in the very early axSpA group were significantly younger, and had less impairment of spinal mobility. TNFi retention was analyzed in 594 patients with available covariate information (75 patients with very early axSpA, 31 patients with early axSpA and 488 patients with established disease; Table 2). We did not find evidence for a difference in retention between very early and established axSpA (HR for drug discontinuation 0.84, 95% CI 0.62-1.15, Table 2). Adjusted BASDAI50 response at 1 year was investigated in 422 patients with complete covariate data (55 patients with very early axSpA, 18 patients with early axSpA and 349 patients with non-early axSpA). A comparable BASDAI50 response was observed in very early vs. established axSpA (OR 0.85, 95% 0.44-1.64), and in early vs. established axSpA (OR 0.79, 95% 0.27-2.25).Table 1. Characteristics of axSpA patients with very early disease and non-early disease at initiation of the first tumor necrosis factor inhibitor. ASDAS = Ankylosing Spondylitis Disease Activity Score; axSpA = axial spondyloarthritis; BASDAI = Bath Ankylosing Spondylitis Disease Activity Index; BASFI = Bath Ankylosing Spondylitis Functional Index; BASMI = Bath Ankylosing Spondylitis Metrology Index; CRP = C-reactive protein; HLA-B27 = human leucocyte antigen-B27; MRI = magnetic resonance imaging).Table 2. Comparison of TNFi retention in patients with very early and early axSpA versus patients with established axSpA.Conclusion:Potential differences in effectiveness of TNFi in patients with very early and established axSpA are probably of a modest effect size, since, in our cohort, we did not find evidence for a difference between the two groups.REFERENCES:[1] Ann Rheum Dis 2023;doi:10.1136/ard-2023-224.232.[2] RMD Open 2023;9:e003455.Acknowledgements:NIL.Disclosure of Interests:Adrian Ciurea: None declared, Andrea Goetschi: None declared, Burkhard Moeller Speaking fees Janssen, Novartis, Pfizer, Eli Lilly, Grant/research support from Amgen, Michael J. Nissen Speaking fees from AbbVie, Amgen, Eli Lilly, Janssen, Novartis, Pfizer, Consulting fees from AbbVie, Eli Lilly, Janssen, Novartis, Pfizer, Research grant from Novartis and Pfizer, Kristina Buerki: None declared, René Braem: None declared, Michael Andor: None declared, Thomas Hügle Payments for lectures and presentations from Pfizer, Fresenius Kabi, AbbVie, Merck Sharp and Dohme, Galapagos, Eli Lilly, Novartis, Holds stocks or stock options from Atreon SA and Vtuls, royalties from Curmed, Participated on Advisory board for DETECTRA, Andrea Rubbert-Roth Honoraria for lectures from AbbVie, Janssen, Novartis, Pfizer, Consulting fees from AbbVie, Janssen, Pfizer, Support for attending meetings from Janssen, Pfizer, Diego Kyburz Honoraria for presentations from AbbVie, Eli Lilly, Participation on advisory boards from AbbVie, Eli Lilly, Janssen, Novartis, Pfizer, Roche, Research grant from AbbVie, support for attending meetings from Janssen and Eli Lilly, Sabine Adler: None declared, Oliver Distler: None declared, Almut Scherer Employed by Bristol-Myers-Squib in 2007-2008, Raphael Micheroli Honoraria for lectures or presentations from AbbVie, Eli Lilly, Janssen, Gilead, and Pfizer.

Background:Juvenile idiopathic arthritis (JIA) represents challenges for women during pregnancy and breastfeeding. Limited research exists on breastfeeding practices among women with JIA. To our knowledge, there are no publications so far investigating the proportion of breastfeeding in mothers with JIA, and if breastfeeding affects disease related factors.Objectives:This study aimed to explore the proportion of women with JIA breastfeeding at 6 weeks, 6 months and 12 months postpartum, as well as examining demographic and disease related factors, and the use of medications, comparing the breastfeeding and the non-breastfeeding groups.Methods:Data from the Norwegian nationwide quality register RevNatus, collecting data about women with inflammatory rheumatic diseases in relation to pregnancy, were analyzed. The data were collected from clinical documentation and self-reported material during visits at the outpatient clinic. All women with JIA with a live birth and attending at least the control 6 weeks postpartum, were included in the study.Results:Among 304 live births in 227 women, 85,5% were breastfed at 6 weeks, 70% at 6 months and 30% at 12 months postpartum. Breastfeeding women had higher educational level, longer pregnancy duration, a lower prevalence of C-sections, lower scores for VAS pain, VAS fatigue and VAS total, and used less conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) compared to women not breastfeeding. 14 women did not specify their breastfeeding status.Conclusion:In the present study, we observed a high proportion of women with JIA breastfeeding at 6 weeks and 6 months postpartum. Based on our findings, women with JIA should be encouraged by health professionals to breastfeed.REFERENCES:NIL.Acknowledgements:NIL.Disclosure of Interests:None declared.

Background : One of the key therapeutic goals in systemic lupus erythematosus (SLE) is the prevention of organ damage. This core domain outcome is often evaluated with the Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) Damage Index (SDI). Access to longitudinal organ damage data on large populations of unselected SLE patients, which currently remain unavailable, would enable real-world investigations of interventions on organ damage accrual. Objectives : We aimed to develop a register-based organ damage index (RBODI) using International Classification of Diseases (ICD)-coded register data, and to evaluate its accuracy to estimate SDI scores from a well-characterised cohort. Furthermore, we used the RBODI to describe rates of organ damage accrual, as well as associations with mortality, in newly diagnosed patients with SLE in a population-based nationwide cohort in Sweden. Methods : In collaboration with practitioners from six medical specialties, we translated original SDI items into ICD-10, Swedish Classification of Surgical and Medical Procedures (KVÅ), and Anatomical Therapeutic Chemical (ATC) codes to calculate a global organ damage score. These codes were retrieved from the National Patient Register (inpatient and outpatient visits) and Prescribed Drug Register, and the RBODI was calculated using similar rules as the SDI, i.e., using the same weighting system, and scoring damage occurring since SLE diagnosis only. Using SDI data from prevalent SLE cases from the Clinical Lupus Register in North-Eastern Gothia cohort (KLURING; 2021) as the gold standard for validation of the RBODI, we estimated the positive predictive value (PPV), sensitivity and specificity to detect the presence of organ damage (SDI=0 versus SDI >0). Among newly diagnosed patients with SLE from the National Patient Register (2005–2022; N=4421), we estimated 5-year cumulative incidences of organ damage overall, and by patient characteristics (age, sex, and year of diagnosis). Cox models were used to estimate the age- and sex-adjusted hazard ratio (HR) of first organ damage accrual (RBODI>0) five years after diagnosis associated with patient characteristics. Lastly, aiming to compare with previous reports from Sweden, among patients with SLE living in Sweden five years after diagnosis (N=3013) we estimated the association between presence of organ damage within the first five years of diagnosis and mortality. Results : We identified 271 prevalent SLE cases with available SDI data in 2021 from KLURING (mean age at diagnosis 41.0±16.4 years, 86.7% female, mean time since diagnosis 16.7±9.1 years, and 62.7% had developed any organ damage). The RBODI displayed good accuracy to discriminate the presence of organ damage as scored with SDI, with a PPV of 85% (95%CI: 79–90%), sensitivity of 81% (95%CI: 74–86%), and specificity of 76% (95%CI: 67–84%; Figure 1). Among newly diagnosed patients with SLE in the nationwide cohort (mean age at diagnosis 47.5±19.8 years, 82.3% female), males (HR: 1.2; 95%CI: 1.1–1.4) and older individuals (>45 years versus ≤45 years; HR 3.4; 95%CI 3.1–3.8) had an increased risk of developing damage within 5 years of diagnosis, while there was no association with year of diagnosis (Figure 2). Patients with organ damage within the first five years of diagnosis had a 3-fold higher hazard of mortality compared with patients with a RBODI=0 during the same period (HR 2.7; 95%CI: 2.0–3.6). Conclusion : Our novel RBODI accurately estimates SDI scores, and allows us to describe long-term trends in damage accrual in the largest cohort of incident SLE to date. The strong association between damage accrual early in the disease course and future mortality highlights the need for treat-to-target strategies that incorporate early and efficient interventions to prevent organ damage.

Background:JAK inhibitors have an increasing role in treating different arthropathies. Yet, there are no head-to-head randomised clinical trials to investigate the superiority of one drug over another. The role of selectivity of different JAK inhibitors on efficacy and drug retention is still unknown, and their side effects profiles among the Middle Eastern ethnicities are still not reported.Objectives:The objective of this study was to assess the difference in retention rate among different JAK inhibitors with different JAK selectivity profiles and identify potential factors affecting the retention rate in the Arab population residing in the Gulf region.Methods:Registry data of patients from eight teritary centers located in Saudi Arabia, United Arab Emirates, and Qatar were used for this study. Data were collected, retrospectively, for all patients who received tofacitinib, baricitinib or upadacitinib over the past eight years. Data analysis was conducted using SPSS 29. Descriptive and inferential statistics were used, as appropriate to the type of data. Level of significance was set at 5%.Results:Data pertaining to a total of 459 patients, who received JAK inhibitors, were analyzed in this study. Of all patients, 245 (53.4%) had tofacitinib, 104 (22.7%) had baricitinib and 110 (24.0%) received upadacitinib. The mean age (sd; range) of the patients was 51.0 (13.5; 16 - 86), 53.6 (15.7; 17 - 93) and 51.9 (14.1; 24 - 93) years for tofacitinib, baricitinib, and upadacitinib, respectively. Among the study patients, 127 (52.0%) of tofacitinib, 36 (36.4%) of baricitinib and 40 (36.4%) of upadacitnib were b-DMARD naïve. The 6 month retention rate was 87.4%, 89.7%, and 73.6% for tofacitinib, baricitinib, and upadacitinib, respectively (Chi-square=13.300, df=2, p-value=0.001), while the 12 month retention rates for Tofacitinib, Baricitinib and Upadacitinib were 74.5%, 70.1% and 57.5%, respectively (Chi-square=9.946, df=2, p-value=0.007). The 3-year retention rates for tofacitinib, baricitinib and upadacitinib were 33.5%, 16.5% and 9.4%, respectively (Chi-square=27.097, df=2, p-value<0.001). The median duration on the drug was 26 months (IQR=30.5), 19 months (IQR=21.5), and 13.5 (IQR=18.3) for tofacitinib, baricitinib and upadacitinib, respectively. The main reasons for drug discontinuation were loss of efficacy (57.6% for Tofacitinib, 57.1% for Baricitinib, and 38.2% for Upadacitinib), and adverse events (11.8% for Tofacitinib, 14.3% for Baricitinib, and 44.1% for Upadacitinib).Conclusion:This real-world evidence registry data suggests potential difference between the retention rate of the three JAK inhibitors with different JAK selectivity indicating potential difference in their efficacy and sustainability. Head to head clinical trial will be required to confirm if there is any superiority of a medication over another.Acknowledgements:NIL.Disclosure of Interests:None declared.

Background:Identifying psoriatic arthritis (PsA) poses challenges, leading to diagnostic delays that have not been thoroughly examined for their impact on the efficacy and retention rates of advanced therapies.Objectives:Our study investigates this gap within a biologic disease-modifying anti-rheumatic drug (bDMARD) registry cohort.Methods:Utilizing data from the TReasure database, a national multicenter observational database in Turkey, this study focused on 360 PsA patients who commenced bDMARD treatment after 2017. Of these, 193 individuals with known time intervals between symptom onset and diagnosis were included. Patient demographics, disease characteristics, and outcomes were gathered at baseline, first, and last visits. Patients were classified based on diagnostic delays (6, 12, or 24 months) to facilitate comparisons.Results:The mean (SD) age was 46 (12) years, the mean duration of PsO was 11 (12) years and the mean duration of PsA was 4.0 (4.9) years. Median (IQR) time between the first symptom onset and diagnosis 24 (48) months, with 70.9%, 51.3%, and 36.2% experiencing more than 6, 12, and 24-month delays, respectively. When there is dactylitis the odds of delay in diagnosis more than 6 months tends to decrease OR 0.46 (95% CI 0.21-1.05, p=0.006). The odds of delay in diagnosis more than 24 months increased with higher Charlson comorbidity index CCI (OR 1.82 (95% CI 0.89-3.68, p=0.006). Patients with delays exceeding 6 months demonstrated significant difference in change in disease activity scales and function scores at the last visit. Patients with delays exceeding 12 months and 24 months had significantly shorter times to switch compared to those with shorter delays (p=0.01 for both) (Figures 1, 2).Conclusion:The prolonged diagnostic delay observed in TReasure PsA underscores its impact: patients with delays exceeding 6 months experienced a more pronounced improvement in pain, disease activity, functionality and fatigue scores compared to baseline. Furthermore, when the delay exceeded 12 months, the time to the first bDMARD change was notably shorter.REFERENCES:NIL.Figure 1.Kaplan-meier curve for retention period on first bDMARD according to diagnostic delay of 12 monthsFigure 2.Kaplan-meier curve for retention period on first bDMARD according to diagnostic delay of 24 monthsAcknowledgements:NIL.Disclosure of Interests:None declared.

Background:Undifferentiated spondyloarthritis (uSpA) refers to a clinical entity within the spectrum of spondyloarthritis (SpA) that does not meet the criteria for a specific subtype as per the ESSG criteria. U-SpA has been described as a potential early form of axial SpA (axSpA) and other specific subtypes. However, there exist discrepancies about the proportion of patients that actually change from this undifferentiated state to a more defined diagnosis over time.Objectives:a) To describe the current diagnoses (e.g. axial SpA (axSpA), peripheral SpA (pSpA), Psoriatic Arthritis (PsA), or others) among patients diagnosed with u-SpA 17 years ago; b) To analyse the factors linked to the change in diagnosis among patients initially diagnosed with u-SpA.Methods:Longitudinal and multicentre study where patients with SpA (according to the ESSG Criteria) from REGISPONSER (assessed in 2004) were re-evaluated 17 years later (2021-2022), resulting in the REGISPON-3 study. REGISPONSER dataset has been combined with the REGISPON-3 data obtaining two visits separated by 17 years. Firstly, a descriptive analysis has been carried out to describe the change in the diagnosis of the u-SpA patients 17 years later according to the rheumatologist’s criteria. Secondly, we studied what the diagnostic changes consist of according to some clinical characteristics and the presence of HLA-B27 using Chi-squared test.Results:A total of 64 patients diagnosed with u-SpA in 2007 were included in this analysis. Table 1 shows how the diagnosis of u-SpA has changed 17 years later. Among the 64 patients with u-SpA, 49 (76.5%) developed axSpA, 7 (10.9%) pSpA, 4 (6.2%) PsA and 4 (6.2%) finally did not have SpA according to the rheumatologist. Table 2 shows the change of the diagnosis of u-SpA according to some clinical characteristics and the presence of HLA-B27. Patients that change to axSpA were more frequently men [26 (53.1%)], HLA-B27 positive [41 (83.7%)], without peripheral joint disease [16 (32.7%)], and without psoriasis [47 (95.9%)], although statistical differences were only found for psoriasis. On the contrary, patients that changed to PsA were more frequently women [3 (75%)], but the prevalence in peripheral joint disease [2 (50%)] and psoriasis [2 (50%)] were similar with no significant differences. Patients who were eventually considered not to meet SpA criteria were more frequently women [4 (100%)], without arthritis [3 (75%)] and without psoriasis [0 (0%)].Conclusion:The diagnosis of u-SpA varies over time, with axSpA being the type most frequently diagnosed in our study 17 years later. Patients without psoriasis and HLA-B27 positives were more frequently diagnosed with axSpA.REFERENCES:NIL.Table 1. Description of the evolution of u-SpA diagnosis over 17 years from REGISPONSER I-II to REGISPON-3AS: ankylosing spondylitis; PsA: psoriatic arthritis; u-SpA: undifferentiated spondyloarthritis; r-AxSpA: non-radiographic axial spondyloarthritis; r-AxSpA: radiographic axial spondyloarthritis.Table 2. Change of the diagnosis of u-SpA according to clinical characteristics and the presence of HLA-B27u-SpA: undifferentiated spondyloarthritis; r-AxSpA: non-radiographic axial spondyloarthritis; r-AxSpA: radiographic axial spondyloarthritis.Sex: p=0.153; HLA-B27: p=0.459; peripheral joint disease: p=0.216; psoriasis: p=0.003**.Acknowledgements:NIL.Disclosure of Interests:None declared.