OBJECTIVES:In patients with psoriatic arthritis, articular responses vary by joint location with both tumour necrosis factor inhibitors (TNFi). It remains unknown whether this also applies to patients with axial spondyloarthritis (axSpA). METHODS:We included patients with axSpA from the European spondyloarthritis research collaboration network (EuroSpA RCN) who initiated a TNFi between 2001-2022. Joint tenderness was used as a proxy for peripheral articular involvement. Among patients with at least one tender joint at treatment start (baseline) based on a 26-joint count (28-joint count excluding the shoulders), resolution of joint tenderness during a two-year follow-up was assessed with a mixed-effects model for interval-censored data, including random effects for country and patient. RESULTS:A total of 1113 patients (43.4% male, mean (SD) age 44.7 (11.7) years) with 5886 tender joints (median (IQR) 3 (2,7) tender joint count) from eight European countries initiating treatment with a TNFi (n=1113) were included. The knee and wrist were most commonly affected at baseline. Compared with the wrist, the rate of joint tenderness resolution was similar in the elbow (HR=1.06, 95%CI 0.88 to 1.28), lower in the knee (HR=0.76, 95%CI 0.64 to 0.90), while higher in all finger joints, particularly in the first interphalangeal joint (HR=2.64, 95%CI 2.05 to 3.40) and in digits four and five (metacarpophalangeal joint (MCP)4 HR=2.19, 95%CI 1.77 to 2.71) and MCP5 (HR=3.16, 95%CI 2.50 to 4.00). CONCLUSION:The peripheral joint response to TNFi in axSpA appears to be location-dependent, indicating that the joint site should be considered when interpreting treatment response.

OBJECTIVES:To compare overweight and obesity prevalence in Swiss patients with psoriatic arthritis (PsA) against the general Swiss population from 2007-2022, evaluate temporal trends, and assess socioeconomic correlates (age, sex, education). METHODS:We performed a repeated cross-sectional analysis of adults with PsA in the Swiss Clinical Quality Management in Rheumatic Diseases (SCQM) registry who had BMI recorded in 2007, 2012, 2017, or 2022 (patients could contribute to more than one index year). Age-, sex-, and education-stratified BMI distributions were compared with Swiss Health Survey data using χ² goodness-of-fit tests. Within PsA, clinical and socioeconomic variables were compared across BMI categories using Fisher's exact or Kruskal-Wallis tests; pairwise changes over time were assessed with one-sided Wilcoxon rank-sum tests. RESULTS:Among 1,150 PsA patients in 2022, 37.6% were overweight and 28.2% obese, versus 30.9% and 12.1% in the Swiss population. In cross-sectional comparisons, obesity was associated with more frequent elevated C-reactive protein (55.8% vs. 37.0%), higher patient global assessment (mean [SD] 3.2 [2.4] vs. 2.8 [2.2]) and physician global assessment (2.5 [2.0] vs. 2.1 [1.8]), and lower EQ-5D-3L health state (0.7 [0.2] vs. 0.8 [0.2]). Obesity prevalence rose from 19.4% in 2007 to 28.2% in 2022, a trend driven by men. Obesity prevalence varied across educational strata but did not follow a monotonic social gradient; within each stratum obesity was markedly more common in PsA than in the Swiss general population. CONCLUSIONS:Overweight and obesity affect nearly two-thirds of Swiss PsA patients and have increased since 2007. Cross-sectional associations between obesity, higher inflammatory burden and poorer patient-reported health state, together with the widening gap versus the general population, support integrating structured, multidisciplinary weight-management programmes into PsA treat-to-target care, particularly for men.

OBJECTIVE:Identifying patient characteristics that predict treatment response in psoriatic arthritis (PsA) may help optimize treat-to-target strategies. We aimed to explore overall and sex-specific predictors of secukinumab (SEC) effectiveness in European patients with PsA treated in routine care. METHODS:We analyzed data from 14 registries in the European Spondyloarthritis (EuroSpA) Research Collaboration. Patients aged ≥ 18 years at diagnosis, initiating SEC treatment from January 2015 to January 2021, were included. Multiple imputation was used for missing covariates at treatment start (baseline) and Disease Activity Index for Psoriatic Arthritis based on 28 joints (DAPSA28) at 6 months. Overall and sex-stratified analyses were performed by logistic and Cox regressions to identify baseline predictors of the following treatment outcomes: (1) DAPSA28 low disease activity (LDA; DAPSA28 ≤ 14) at 6 months, (2) DAPSA28 moderate response at 6 months, and (3) SEC discontinuation within 12 months. RESULTS:In total, 2790 patients (43% male) were included. Median age was 43 years (IQR 34-52), and SEC was the first-line biologic/targeted synthetic disease-modifying antirheumatic drug (b/tsDMARD) in 665 patients (24%). Positive predictors for both DAPSA28 LDA and DAPSA28 moderate response were male sex, fewer previous b/tsDMARDs, C-reactive protein (CRP) > 10 mg/L, and lower Health Assessment Questionnaire (HAQ) score. Absence of psoriasis, higher patient fatigue, and tender joint counts predicted SEC discontinuation within 12 months. For some outcomes, sex-specific predictors were fewer previous b/tsDMARDs and CRP > 10 mg/L among male patients and lower patient fatigue score among female patients. CONCLUSION:We identified overall and sex-specific predictors of SEC effectiveness in European patients with PsA. Our findings may support personalized treatment decisions.

Objectives In patients with psoriatic arthritis (PsA) initiating treatment with secukinumab, we investigated the impact of smoking and body mass index (BMI) on secukinumab retention rate at 12 months and the achievement of low Disease Activity Index for PsA in 28 joints (DAPSA28 ≤14) at 6 months. Methods Patients with PsA initiating secukinumab with available data on smoking and BMI were included. Patients were categorised according to smoking status (never/former/current) and BMI (normal/overweight/obese) at treatment start. Kaplan-Meier curves and adjusted Cox and logistic regression analyses were performed to compare secukinumab retention and response rates, respectively. Additional regression analyses were performed with BMI as a continuous variable. Results We included 1202 patients. Retention rates in never/former/current smokers were 79%/73%/72% and in normal/overweight/obese 72%/77%/77%, respectively. Adjusted hazard ratios for treatment withdrawal were numerically higher in former (1.32; 95 % CI 1.00-1.75) and current smokers (1.27; 0.93-1.74), while remaining roughly similar across BMI (overweight: 0.90; 0.67-1.21, obese: 0.89; 0.66-1.21, per BMI unit: 1.00; 0.97-1.02). Response rates in never/former/current smokers were 56%/61%/49% and in normal/overweight/obese 57%/59%/52%, respectively. Adjusted odds ratio for achieving low DAPSA28 was numerically lower for current smokers (0.74; 0.47-1.15) but higher for former smokers (1.30; 0.87-1.94), whereas it was numerically lower in patients with obesity (0.74; 0.49-1.11) and lower with each increase in BMI unit (0.97; 0.94-1.00). Conclusions In real-world patients with PsA, secukinumab retention tended to be lower in current and former smokers. No clear association between BMI and secukinumab effectiveness was observed.

Objectives This study aimed to compare prevalence, anatomical distribution, and associated factors of enthesitis in psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA) in routine care. Methods Cross-sectional analysis of the Swiss Clinical Quality Management in Rheumatic Diseases (SCQM) registry. Patients with PsA or axSpA enrolled from 2018 to 2024 with an available Maastricht Ankylosing Spondylitis Enthesitis Score (MASES) recorded at first visit during study period were included. Enthesitis was defined as a MASES score of > 0. Axial PsA (axPsA) was analysed descriptively for anatomical distribution. Multivariable negative binomial regression modelled entheseal burden, adjusting for age, sex, body mass index (BMI), C-reactive protein levels, symptom duration, and current biologic or targeted synthetic disease-modifying antirheumatic drug use. Results We included 3885 patients (PsA, 1473; and axSpA, 2412). Enthesitis prevalence was 56.6% in PsA and 64.9% in axSpA. Among patients with any enthesitis, mean MASES score was 2.8 in PsA, 3.0 in axPsA, and 3.2 in axSpA. Posterior superior iliac spine and L5 spinous process were the most frequently affected sites. Achilles tendon involvement was more prominent in PsA and axPsA, whereas costochondral sites were more frequent in axSpA. Female sex, elevated C-reactive protein levels, higher BMI levels, and current smoking were consistently associated with higher enthesitis burden. Longer symptom duration and biologic disease-modifying antirheumatic drug use were associated with lower burden. No differential effects of BMI or smoking by diagnosis or sex were detected. Conclusions Enthesitis is common in PsA and axSpA, with distinct anatomical patterns but largely shared associated factors. Obesity, smoking, and systemic inflammation may represent relevant targets for intervention alongside pharmacologic management, though longitudinal studies are needed to confirm these associations.

Objectives To investigate associations between cardiometabolic comorbidities and clinical characteristics, prescription patterns and retention of first biologic/targeted synthetic disease-modifying anti-rheumatic drug (b/tsDMARD) in patients with psoriatic arthritis (PsA).Methods Patients with PsA initiating a first b/tsDMARD treatment in 2015 or later were identified in eight European rheumatology registries. Patients with information on five cardiometabolic comorbidities (obesity, dyslipidaemia, diabetes, hypertension, ischaemic heart disease) at treatment start (baseline) were included. All analyses were conducted according to patients’ comorbidity burden (count: 0/1/≥2) and status (presence/absence of each comorbidity). Patient characteristics and prescription patterns were described. Twelve-month treatment retention rates were estimated and compared using Kaplan-Meier plots, log-rank tests and multivariable Cox regression analyses.Results Among 5299 patients, 36% had at least one cardiometabolic comorbidity. Patients with comorbidity were older, had higher disease activity and more disability. Regardless of comorbidity, most patients were prescribed a tumour necrosis factor inhibitor (76%). The use of interleukin-17 inhibitors increased with comorbidity burden (0/1/≥2 comorbidities: 13%/18%/19%), whereas Janus kinase inhibitor use declined (2.3%/1.6%/0.8%). Retention rates were marginally lower with higher comorbidity burden (80%/76%/78%) (log-rank, p=0.036) and obesity (absent 79% vs present 77%) (log-rank, p=0.04). The risk of treatment withdrawal was only marginally higher in patients with higher comorbidity burden (one comorbidity: HR 1.19; 95% CI 1.02 to 1.40; ≥2 comorbidities: HR 1.18; 0.98 to 1.42).Conclusion Patients with cardiometabolic comorbidities had higher disease activity at treatment initiation of the first b/tsDMARD. Prescription patterns varied with comorbidity burden. Cardiometabolic comorbidity burden, especially obesity, was associated with marginally lower treatment retention.

Background: Up to one-third of people living with psoriasis develop psoriatic arthritis (PsA), and the majority have active psoriasis prior to the development of arthritis. Clinical risk factors, such as nail involvement, in conjunction with novel blood biomarkers, could improve PsA risk monitoring and early diagnosis. Objectives: The aim of the HIPPOCRATES Prospective Observational Study (HPOS— www.hpos.study ) is to follow a cohort living with psoriasis and identify risk factors for the development of PsA. Design: HPOS is a patient-driven online prospective European observational cohort. Methods: Adult participants with psoriasis but with no prior diagnosis of PsA are eligible. Participants are invited to provide consent and join the study online. They complete a semi-structured questionnaire to collect data on demographics, psoriasis, comorbidities, risk factors for PsA, and the Psoriasis Epidemiology Screening Tool screening questionnaire. Follow-up is conducted through a questionnaire every 6 months. The primary outcome is the new onset of PsA confirmed by a diagnosis from their doctor. The study will also collect peripheral blood samples from a subset of participants for biomarker identification. Ethics: This study follows the principles of the Declaration of Helsinki. To date, ethical approval has been granted by independent ethical committees in 10 countries. Discussion: Studying a cohort of individuals with psoriasis will allow us to identify risk factors for arthritis development and to develop a risk calculator. This can support focused efforts on screening, patient education, and even studies looking to delay or prevent the onset of arthritis. This study, run via remote online data collection, provides an efficient way to recruit a large cohort (25,000) across multiple countries. However, challenges have had to be addressed with some key changes in study design, ethical review, and recruitment strategies required for each individual country. Trial registration: HPOS, Clinicaltrials.gov ID: NCT05858528, IRAS number 325080; https://clinicaltrials.gov/study/NCT05858528?locStr=United%20Kingdom&country=United%20Kingdom&cond=Psoriasis&term=HPOS&aggFilters=status%3Anot%20rec&rank=1 .

Objective To characterise patients with ‘very early’ axial spondyloarthritis (axSpA), defined as a duration ≤1 year of back pain and to determine the effectiveness of a first tumour necrosis factor inhibitor (TNFi) in very early versus established axSpA in a large observational registry.Methods We included a total of 3324 patients with axSpA from the Swiss Clinical Quality Management in Rheumatic Diseases registry with available data on duration of back pain (≤1 year=very early axSpA, n=441; >1 year and ≤2 years=early axSpA, n=218; >2 years=established axSpA, n=2575). A first TNFi was started in 31%, 38% and 36% of patients with very early, early and established axSpA. Adjusted logistic regression models were used to compare the probability of achieving low disease activity status according to the Axial Spondyloarthritis Disease Activity Score (ASDAS <2.1) at 1 year. Drug survival was analysed with multiple-adjusted Cox proportional hazards models. Missing data were handled using multiple imputation by chained equations.Results Objective signs of inflammation were more prevalent in very early disease. No difference was found regarding the achievement of ASDAS <2.1 after adjustment for age, sex, human leucocyte antigen-B27 status, education, body mass index, smoking, ASDAS and sacroiliac inflammation on MRI (OR 1.08, 95% CI 0.70 to 1.68 in very early vs established axSpA). Similarly, no significant difference in TNFi retention was found in very early versus established axSpA (HR for drug discontinuation 1.05, 95% CI 0.84 to 1.31).Conclusion We found no evidence for a better effectiveness of TNFi in patients with very early versus established axSpA.

Therapeutic targeting of ferroptosis, particularly in pathogenic fibroblast-like synoviocytes, could hold promise for rheumatoid arthritis. However, ferroptosis research in health and disease is still in its infancy, and further research is needed to identify specific therapeutic targets, inform drug development and assess the possible effects of targeting ferroptosis in other cell types and tissues.

Objectives This study aimed to determine the effectiveness of a first tumour necrosis factor inhibitor (TNFi) in patients with short and long symptom duration in axial spondyloarthritis (axSpA), using alternative cut-offs for back pain duration: ≤1 year as very early, >1 year, and ≤5 years as intermediate axSpA, and >5 years as late axSpA. Methods A total of 1161 patients with axSpA from the Swiss Clinical Quality Management registry, who had data on the duration of back pain and initiated their first TNFi, were included. Patients were categorised as follows: very early axSpA (N = 138), intermediate axSpA (N = 329), and late axSpA (N = 694). Adjusted logistic regression models were used to compare the likelihood of achieving a low disease activity status (Axial Spondyloarthritis Disease Activity Score [ASDAS] <2.1) at 1 year, adjusting for age, sex, human leucocyte antigen-B27, educational level, body mass index, ASDAS, current smoking, and presence of inflammation on magnetic resonance imaging of the sacroiliac joints. Drug survival was analysed using multiple-adjusted Cox proportional hazards models. Missing data were addressed through multiple imputation by chained equations. Results Higher disease activity parameters were found at baseline in very early axSpA. However, no significant differences were observed in treatment response or TNFi retention between very early and late axSpA (odds ratio for ASDAS < 2.1 response 0.99, 95% CI: 0.62-1.59 and hazard ratio for drug discontinuation 1.09, 95% CI: 0.87-1.37). Conclusions Based on this real-world observational data, no evidence was found to suggest a superior effectiveness of TNFi in patients with very early axSpA compared with those with late axSpA.

Objectives Whether treatment response differs across affected joints in rheumatoid arthritis (RA) remains unclear. We sought to determine whether responses to tumour necrosis factor inhibitors (TNFi) and other biologic/targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) vary across individual joints in a large cohort of patients with RA. Methods Patients with RA from the Swiss Clinical Quality Management in Rheumatic Diseases registry with ≥1 swollen joint at treatment initiation of a b/tsDMARD (abatacept, interleukin-6 receptor inhibitor (IL-6Ri), Janus kinase inhibitor (JAKi), rituximab and TNFi) were included. Time to resolution of swollen joints was evaluated over a 2-year follow-up using mixed effects models accounting for interval-censored data. The analyses compared the speed of improvement of individual joints within the 28-joint count to that of the wrist. The primary analysis focused on bio-naïve patients initiating TNFi treatment, while secondary analyses included all b/tsDMARD classes, irrespective of treatment line. Results A TNFi was initiated in 598 patients with ≥1 swollen joint, while 1942 patients with ≥1 swollen joint started a b/tsDMARD (abatacept: 242, IL-6Ri: 317, JAKi: 333, rituximab: 176, TNFi: 874). Compared with the wrist, all joints demonstrated higher rates of resolution, except for the second and third metacarpophalangeal (MCP2/3) joints and, in some analyses, the knee. This pattern of joint-specific response was consistent across all b/tsDMARDs. Conclusions The wrist, MCP2 and MCP3 joints resolve more slowly than other joints following treatment with b/tsDMARDs, indicating that a longer evaluation period of treatment response and/or bridging intra-articular steroid injections may be required when these joints are affected.

According to the modified New York criteria (mNYc), moderate-severe sacroiliac joint (SIJ) structural damage on radiography is necessary for classifying radiographic axial spondyloarthritis (r-axSpA). In contrast to radiography, MRI provides no ionizing radiation, higher sensitivity for structural damage, better inter-reader reliability, and is gradually replacing radiography. Therefore, we aimed to develop and validate a high specificity MRI cut-off to the radiographic component of the mNYc (rad-mNYc), defined as MRI findings that correspond to an mNY-positive radiograph. Patients diagnosed with axSpA with available SIJ MRI and radiograph from five European clinical registries in the EuroSpA Collaboration were included. MRIs were read according to the SPARCC structural score (based on 5 predefined or all slices) and radiographs the rad-mNYc. Cut-offs with 95

OBJECTIVES:To explore the association between national socioeconomic indicators, and (i) 6/12/24-month retention of biologic/targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARD), and (ii) disease activity at treatment start, in patients with psoriatic arthritis (PsA) or axial spondyloarthritis (axSpA). METHODS:Longitudinal data from 13 European countries, including 38,911 patients with spondyloarthritis (17,296 PsA and 21,615 axSpA) initiating b/tsDMARDs in 2015-2021, were collected by the European Spondyloarthritis Research Collaboration Network. Kaplan-Meier, mixed-effects Cox regression, linear regression, and mixed models were used for comparisons across countries with low/medium/high national socioeconomic indicators (gross domestic product [GDP], Human Development Index [HDI], gross national income, current health expenditure, out-of-pocket expenditure), stratified by disease/b/tsDMARD number/sex. RESULTS:Drug retention was significantly lower in both men and women with PsA/axSpA from countries with high vs medium/low GDP per capita after 6/12/24 months' treatment with 1st/≥2nd b/tsDMARD (log rank P < .001). For all socioeconomic indicators, higher wealth was associated with earlier discontinuation of 1st b/tsDMARD both in PsA and axSpA men and women. The strength of associations varied across indicators, treatment lines, and sex. The strongest associations between socioeconomic measures and b/tsDMARD retention were seen with GDP per capita and HDI, and most prominently in women with axSpA. At the country level, most disease activity measures at the start of 1st/≥2nd b/tsDMARD were significantly worse with lower GDP, particularly for PsA. CONCLUSIONS:Treatment retention varies with countries' socioeconomic status. Clinicians and health policy makers should be aware of later discontinuation/switching of b/tsDMARDs and a tendency to higher country-level disease activity at b/tsDMARD initiation in lower-income countries.

Efficacy of tumour necrosis factor inhibitors (TNFi) for peripheral arthritis in patients with psoriatic arthritis (PsA) has been established in randomized clinical trials that have used improvement in summated joint counts as an outcome. Whether joints at different anatomical locations might respond differentially to TNFi remains unknown. The aim of the study was to investigate potential variations in the responsiveness to a first tumour necrosis factor inhibitor (TNFi) among joints at distinct locations in patients with psoriatic arthritis (PsA) treated in routine clinical care. Bionaive PsA patients from nine European countries were included in this observational cohort study if ≥ 1 joint was swollen at the initiation of a first TNFi as monotherapy or added to methotrexate. Only the 28-joint count was available without imaging data confirming the presence of synovitis. The primary outcome was time to first resolution of joint swelling at each joint level. Hazard ratios (HR) for resolution comparing different joint locations were estimated using interval-censored mixed-effects Cox proportional hazards models, including a random effect for country and patient, adjusted for age and sex. A total of 1729 patients with 8397 swollen joints at the start of TNFi were included. Considering the upper extremity, a higher rate of resolution of joint swelling (HR, 95

Background Studies on national policies for biologics are warranted. Objectives To map and compare national healthcare set-ups for prescription, start, switch, tapering, and discontinuation of biologic/targeted synthetic disease-modifying antirheumatic drugs (DMARDs) in patients with psoriatic arthritis and axial spondyloarthritis across Europe, and assess the healthcare set-ups in relation to countries’ socio-economic status. Methods An electronic survey was developed to collect and compare information on national healthcare systems. The relationship between the cumulative score of biologic/targeted synthetic DMARD regulations, socioeconomic indices, and biologic originator costs were assessed by linear regression. Results National healthcare set-ups differed considerably across the 15 countries, with significantly fewer regulations with increasing socioeconomic status measured by GDP/current health expenditure/human development index, and with increasing biologic originator costs. In most countries, the biologic/targeted synthetic DMARD prescribing doctor was required to adhere to country and/or hospital recommendations, and about a third of countries had a national/regional tender process. Prescription regulations for biologic/targeted synthetic DMARDs, including pre-treatment and disease activity requirements, varied substantially. Approximately a third of countries had criteria for discontinuation and tapering, whereas only few had for switching. Notably, two countries disallowed biologic/targeted synthetic DMARD retrials, and one imposed limit on the maximum number of biologic/targeted synthetic DMARDs permitted. Conclusion The findings highlight substantial variability in healthcare set-ups for biologic/targeted synthetic DMARD use in psoriatic arthritis and axial spondyloarthritis across Europe and their association with socioeconomic status and drug costs. These insights provide a basis for rheumatology societies, policymakers, and stakeholders to evaluate and potentially optimize healthcare policies.

Die Psoriasisarthritis (PsA) ist eine komplexe, polygenetische chronische Erkrankung, die Haut, Nägel und den Bewegungsapparat betrifft. Die Diagnose beruht auf der persönlichen und der Familienanamnese und der klinischen Untersuchung, die durch die Bildgebung einschliesslich Röntgen ergänzt werden sollte. Therapieansätze reichen von Methotrexat über TNF-Blocker bis zu Interleukin-Inhibitoren (IL-17, IL-23), wobei GRAPPA- und EULAR-Guidelines die Behandlungsstrategien leiten. Precision Medicine gewinnt an Bedeutung, um Therapien gezielter einzusetzen. Trotz moderner Therapien bleibt die PsA eine Herausforderung, da nicht alle Patienten eine minimale Krankheitsaktivität erreichen. Eine frühe Diagnose und individuelle Therapieoptimierung sind entscheidend für die Lebensqualität der Betroffenen.

Background: Observational data on composite scores often comes with missing component information. When a complete-case (CC) analysis of composite scores is unbiased, preferable approaches of dealing with missing component information should also be unbiased and provide a more precise estimate. We assessed the performance of several methods compared to CC analysis in estimating the means of common composite scores used in axial spondyloarthritis research. Methods: Individual mean imputation (IMI), the modified formula method (MF), overall mean imputation (OMI), and multiple imputation of missing component values (MI) were assessed either analytically or by means of simulations from available data collected across Europe. Their performance in estimating the means of the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), the Bath Ankylosing Spondylitis Functional Index (BASFI), and the Ankylosing Spondylitis Disease Activity Score based on C-reactive protein (ASDAS-CRP) in cases where component information was set missing completely at random was compared to the CC approach based on bias, variance, and coverage. Results: Like the MF method, IMI uses a modified formula for observations with missing components resulting in modified composite scores. In the case of an unbiased CC approach, these two methods yielded representative samples of the distribution arising from a mixture of the original and modified composite scores, which, however, could not be considered the same as the distribution of the original score. The IMI and MF method are, thus, intrinsically biased. OMI provided an unbiased mean but displayed a complex dependence structure among observations that, if not accounted for, resulted in severe coverage issues. MI improved precision compared to CC and gave unbiased means and proper coverage as long as the extent of missingness was not too large. Conclusions: MI of missing component values was the only method found successful in retaining CC’s unbiasedness and in providing increased precision for estimating the means of BASDAI, BASFI, and ASDAS-CRP. However, since MI is susceptible to incorrect implementation and its performance may become questionable with increasing missingness, we consider the implementation of an error-free CC approach a valid and valuable option. Trial registration: Not applicable as study uses data from patient registries.

Objectives To identify in a genetically susceptible population individuals at higher risk of developing rheumatoid arthritis (RA) using a classification approach combining known epidemiological risk factors, serological biomarkers, genetics, clinical signs and symptoms.Methods We used data from the prospective SCREEN-RA (Evaluation of a SCREENing strategy for Rheumatoid Arthritis) cohort of 1540 first-degree relatives of RA patients (RA-FDRs). The primary outcome was the development of RA. Additionally, we used seropositive inflammatory arthritis (IA) as a secondary outcome for exploratory analyses. Balanced random forest (BRF) models were fit and evaluated through fivefold cross-validation to avoid overfitting. We chose a classification threshold that targeted high sensitivity.Results After a mean follow-up of 7.1 years, 27 participants developed RA and 126 developed seropositive IA. The BRF demonstrated moderate predictive performance, characterised by high sensitivity (≥0.85) but modest specificity. Rheumatoid factors (RFs) had the highest importance in RA prediction, followed by symptoms of ‘clinically suspected arthralgia’ (CSA) scale. Age, gender and anti-RA33 autoantibodies were the main variables for the prediction of seropositive IA.Conclusions Overall, the results demonstrate that predicting RA by combining genetics, serological biomarkers, epidemiological risk factors and clinical signs is promising, although model generalisation remains challenging. The low prevalence of RA in the cohort complicates the development of highly accurate prediction models. Future efforts should focus on including external validation and potentially incorporating additional biomarkers to enhance the sensitivity and overall performance of the predictive tests.

Objective To investigate possible variations in treatment response to secukinumab at distinct anatomic joint locations in patients with psoriatic arthritis (PsA) in routine clinical care. Methods Patients with PsA monitored in 9 registries contributing to the European Spondyloarthritis Research Collaboration Network were included in this study if at least 1 joint from the 28-joint count was clinically swollen at the start of treatment with secukinumab. The primary outcome was time to first resolution of clinical joint swelling at each joint location, excluding the shoulder, during a follow-up of 2 years. Estimated hazard ratios (HRs) for resolution between different joint locations were compared with interval-censored mixed-effects transformation models adjusted for age, sex, and previous biologic/targeted synthetic disease-modifying antirheumatic drug (DMARD). Results A total of 590 patients with 2794 swollen joints at the initiation of secukinumab were included (mean [SD] age 51.7 [12.3] years, 54% female patients, 77% co-treatment with conventional synthetic DMARDs). Compared with the wrist, the elbow had a higher rate of resolution of joint swelling (HR = 1.75, 95% CI = 1.10-2.79). The metacarpophalangeal joints (MCP) 4 and 5 (HR = 2.01, 95% CI = 1.40-2.88 and HR = 1.98, 95% CI = 1.28-3.06, respectively), as well as most proximal interphalangeal joints (PIP), except PIP3, had a higher rate of resolution compared with the wrist. No significant difference in the resolution of joint swelling was found for the wrist compared with MCP2, MCP3, PIP3, and the knee. Conclusions In PsA, the time to resolution of joint swelling after initiation of secukinumab differs between distinct joint locations.