Transcriptomic network analysis reveals key drivers of response to anti-TNF biologics in patients with rheumatoid arthritis.

OBJECTIVE: Anti-TNF biologics have been widely used to ameliorate disease activity in patients with rheumatoid arthritis (RA). However, a large fraction of patients show a poor response to these agents. Moreover, no clinically applicable predictive biomarkers have been established. This study aimed to identify response-associated biomarkers using longitudinal transcriptomic data in two independent RA cohorts. METHODS: RNA sequencing data from peripheral blood cell samples of Korean and Caucasian RA cohorts before and after initial treatment with anti-TNF biologics were analyzed to assess treatment-induced expression changes that differed between highly reliable excellent and null responders. Weighted correlation network, immune cell composition, and key driver analyses were performed to understand response-associated transcriptomic networks and cell types and their correlation with disease activity indices. RESULTS: In total, 305 response-associated genes showed significantly different treatment-induced expression changes between excellent and null responders. Co-expression network construction and subsequent key driver analysis revealed that 41 response-associated genes played a crucial role as key drivers of transcriptomic alteration in four response-associated networks involved in various immune pathways: type I interferon signalling, myeloid leucocyte activation, B cell activation, and NK cell/lymphocyte-mediated cytotoxicity. Transcriptomic response scores that we developed to estimate the individual-level degree of expression changes in the response-associated key driver genes were significantly correlated with the changes in clinical indices in independent patients with moderate or ambiguous response outcomes. CONCLUSIONS: This study provides response-specific treatment-induced transcriptomic signatures by comparing the transcriptomic landscape between patients with excellent and null responses to anti-TNF drugs at both gene and network levels.

Safety and tolerability of bone marrow-derived mesenchymal stem cells in lupus animal models and a phase I clinical trial in humans.

OBJECTIVE: Several clinical trials aimed at treating various autoimmune diseases, including systemic lupus erythematosus (SLE), by introducing mesenchymal stem cells (MSCs) have been conducted. However, with refractory lupus nephritis (LN), the outcomes of MSC transplantation are not well known, and further validation is required. In particular, data concerning the safety and efficacy of LN treatment using bone marrow-derived MSCs (BM-MSCs) are still lacking. METHODS: We identified characteristics of BM-MSCs in terms of cell morphology, chromosomal stability, differentiation capacity, and phenotype through cell passages. The in vivo stability of BM-MSCs was evaluated by single-dose and repeated-dose toxicity tests, tumorigenicity tests, and biodistribution tests using lupus mouse models. Based on the encouraging nonclinical results, we conducted a nonrandomized, open-label, single-arm phase I clinical trial to evaluate the tolerability and safety of a single administration of haploidentical allogeneic BM-MSCs (CS20AT04) in seven LN patients (NCT03174587). We used a classical three + three design to find the optimal dosage. The starting dose was 2.0×106 cells/kg and escalated to 3.0×106 cells/kg if there was no dose-limiting toxicity (DLT). Evaluation of the safety and tolerability was assessed 28 days after the infusion, and the maximum tolerated dose was determined. RESULTS: Properly cultured BM-MSCs showed high proliferation and multipotency, but chromosomal changes were not found. There were two deaths by a rapid administration rate in the high-dose group (2.0×106 cells/head) in a single administration test. BM-MSCs were distributed in the kidneys until Day 7. In the phase I clinical trial, seven LN patients were enrolled. Participants received BM-MSCs through intravenous infusion. There was no DLT at both initial dose (2.0×106 cells/kg) and escalated dose (3.0×106 cells/kg). One patient was not administered the full 2.0×106 cells/kg dose because of a technical error during infusion. This patient did not show DLT. Three adverse events were reported, namely, one diarrhea, one toothache, and one arthralgia, and all were considered NCI-CTC grade I events. CONCLUSION: We defined the characteristics of BM-MSCs and identified their safety and tolerability in both animal models and a phase I clinical trial. The maximum tolerated dose was determined to be 3.0×106 cells/kg in patients with LN.

Fracture Risk and Its Prevention Patterns in Korean Patients with Polymyalgia Rheumatica: a Retrospective Cohort Study.

BACKGROUND: To evaluate the incidence of fractures and fracture risk factors in Korean patients with polymyalgia rheumatica (PMR). METHODS: All PMR patients who visited a rheumatology clinic at a tertiary referral hospital between March 2005 and March 2018 were retrospectively assessed. We estimated bone mineral density (BMD) screening rate within 6 months of the first visit and classified the patients according to the performance and results of BMD screening. Incidence rates (IRs) of fractures were calculated in each group and risk factors for fractures were identified using Poisson regression analysis. RESULTS: A total of 95 PMR patients with median (interquartile range) age of 64.0 (56.0-72.0) years were included. Baseline BMD was assessed in only 55.8% of these patients (n = 53); 24 patients with osteoporosis, 20 with osteopenia, and 9 with normal BMD. During 433.1 person-years (PYs) of observation, 17 fractures occurred in 12 patients (IR, 3.93 [95% confidence interval (CI), 2.46-6.26]/100 PYs); 8.32 (95% CI, 4.09-16.90)/100 PYs in the osteopenia group, 3.40 (95% CI, 1.30-8.90)/100 PYs in the osteoporosis group, and 3.37 (95% CI, 1.53-7.39)/100 PYs in the no BMD test group. Risk factors for fractures were female sex, advanced age (≥ 65 years), longer follow-up duration, initial glucocorticoid dose ≥ 10 mg/day, and higher cumulative glucocorticoid dose over the first 6 months. CONCLUSION: The incidence rate of fractures in Korean patients with PMR was 3.93/100 PYs. Female sex, advanced age, longer follow-up duration, and increased glucocorticoid dose are risk factors for osteoporotic fracture.

Genome-wide association study in a Korean population identifies six novel susceptibility loci for rheumatoid arthritis.

OBJECTIVE: Genome-wide association studies (GWAS) in rheumatoid arthritis (RA) have discovered over 100 RA loci, explaining patient-relevant RA pathogenesis but showing a large fraction of missing heritability. As a continuous effort, we conducted GWAS in a large Korean RA case-control population. METHODS: We newly generated genome-wide variant data in two independent Korean cohorts comprising 4068 RA cases and 36 487 controls, followed by a whole-genome imputation and a meta-analysis of the disease association results in the two cohorts. By integrating publicly available omics data with the GWAS results, a series of bioinformatic analyses were conducted to prioritise the RA-risk genes in RA loci and to dissect biological mechanisms underlying disease associations. RESULTS: We identified six new RA-risk loci (SLAMF6, CXCL13, SWAP70, NFKBIA, ZFP36L1 and LINC00158) with pmeta<5×10-8 and consistent disease effect sizes in the two cohorts. A total of 122 genes were prioritised from the 6 novel and 13 replicated RA loci based on physical distance, regulatory variants and chromatin interaction. Bioinformatics analyses highlighted potentially RA-relevant tissues (including immune tissues, lung and small intestine) with tissue-specific expression of RA-associated genes and suggested the immune-related gene sets (such as CD40 pathway, IL-21-mediated pathway and citrullination) and the risk-allele sharing with other diseases. CONCLUSION: This study identified six new RA-associated loci that contributed to better understanding of the genetic aetiology and biology in RA.

A phase III, multicentre, randomised, double-blind, active-controlled, parallel-group trial comparing safety and efficacy of HD203, with innovator etanercept, in combination with methotrexate, in patients with rheumatoid arthritis: the HERA study.

OBJECTIVES: To evaluate equivalence in efficacy for rheumatoid arthritis (RA) and compare the safety of the biosimilar HD203 with innovator etanercept (ETN) plus methotrexate (MTX) (ClinicalTrials.gov NCT01270997). METHODS: Patients with active RA received 25 mg HD203 or ETN subcutaneously twice-weekly with MTX for 48 weeks in a phase III, multicentre, randomised, double-blind, parallel-group design. The primary end point was the proportion of patients achieving the American College of Rheumatology 20% response (ACR20) at week 24 for per-protocol study completer set (PPS). Secondary end points included ACR response criteria, ACRn, European League against Rheumatism (EULAR) response, change in Disease Activity Score 28 (DAS28), patient-reported outcomes, safety and immunogenicity. RESULTS: Of the 294 randomised patients (HD203, n=147; ETN, n=147), 233 comprised the 24-week PPS (n=115 and 118, respectively). ACR20 at week 24 was achieved by 83.48% and 81.36% of PPS patients, respectively, demonstrating equivalent efficacy within predefined margins of ±20% (treatment difference 2.12%, 95% CI -7.65% to 11.89%). Outcomes for secondary end points were consistent with the primary efficacy findings. Groups were comparable for overall incidences of treatment-emergent (all-causality) adverse events (AEs) (HD203 113 (76.9%) vs ETN 114 (78.1%) (p=0.804)), adverse drug reactions, serious AEs and discontinuations due to AEs. Few patients (HD203, n=8; ETN, n=3) tested positive for anti-drug antibodies. CONCLUSION: The study met the primary objective of demonstrating equivalent efficacy of HD203 and ETN. HD203 was well tolerated, with safety comparable with ETN in this population of patients with RA. TRIAL REGISTRATION NUMBER: NCT01270997; Results.

Characteristics and outcomes of rheumatoid arthritis patients who started biosimilar infliximab.

To compare the characteristics of rheumatoid arthritis (RA) patients receiving either biosimilar or originator infliximab and to identify the effectiveness and safety of biosimilar infliximab in RA patients in real-world practice. RA patients who started either biosimilar or originator infliximab were selected using the prospective biologic disease-modifying anti-rheumatic drugs (DMARDs) registry: BIOlogics Pharmacoepidemiologic StudY (BIOPSY). Baseline characteristics of the two groups were compared, and short-term treatment outcomes, including DAS28-ESR and HAQ-DI scores, were compared after initiation of biosimilar or originator infliximab. The drug retention rates of the two groups were also compared. A total of 100 RA patients, 55 biosimilar, and 45 originator infliximab users were included in this analysis. Baseline characteristics of age, disease duration, and previous or current medications were similar in the two groups. Baseline DAS28-ESR was higher in the originator infliximab group (6.3 ± 1.1 vs. 5.8 ± 1.1, p = 0.02). The early DAS28-ESR remission rates observed 7.9 ± 1.8 months after starting biosimilar and originator infliximab were 15.0 and 25.0%, respectively (p = 0.47). The change in HAQ-DI did not differ between the two groups (0.4 ± 0.7 vs. 0.4 ± 0.8, p = 0.94). Patients treated with biosimilar infliximab in clinical practice had lower disease activity at the start of treatment than those receiving originator infliximab. Biosimilar infliximab was well-tolerated, safe, and of similar clinical effectiveness to originator infliximab. Larger number of patient and longer follow-up data will be needed to confirm the effectiveness and safety of biosimilar infliximab in clinical practice.

Impact of interstitial lung disease on mortality of patients with rheumatoid arthritis.

To identify the prevalence of interstitial lung disease (ILD) in Korean patients with rheumatoid arthritis (RA) and assess its effect on mortality. A total of 3555 patients with RA, with chest X-ray or chest computed tomography (CT) data at enrollment were extracted from the KORean Observational study Network for Arthritis cohort, a nationwide prospective cohort for patients with RA in Korea. The patients were classified into two groups: (1) an ILD group by chest X-ray or chest CT scan, and (2) a non-ILD group by these modalities. After comparing the characteristics of the groups at enrollment, mortalities were compared using the log-rank test. To explore the impact of ILD on mortality, Cox proportional hazard models were used. Sixty-four patients (1.8%) were identified with ILD. Male and older patients were more common in the ILD group. During a mean follow-up of 24 months, 6 patients (9.4%) in the ILD group and 25 patients (0.7%) in the non-ILD group died; the survival rate was significantly worse in the ILD group (p < 0.01). On adjusted analysis, ILD was significantly associated with increased mortality (HR 7.89, CI 3.16-19.69, p < 0.01); the risk of death in patients with ILD was even higher than in patients with cardiovascular disease (CVD, HR 4.10, CI 1.79-9.37, p < 0.01). The prevalence of ILD was 1.8% in Korean patients with RA. ILD is a major risk factor for mortality in patients with RA.

Comparative effectiveness of treatment options after conventional DMARDs failure in rheumatoid arthritis.

OBJECTIVE: To compare the clinical effectiveness of two treatment strategies for active rheumatoid arthritis (RA) refractory to conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs): starting TNF inhibitors (TNFIs) or changing csDMARDs. METHODS: We used two nationwide Korean RA registries for patient selection. TNFI users were selected from the BIOPSY, which is an inception cohort of RA patients starting biologic DMARDs. As a control group, we selected RA patients with moderate or high disease activity from the KORONA database whose treatment was changed to other csDMARDs. After comparing baseline characteristics between the two groups in either unmatched or propensity score matched cohorts, we compared potential differences in the 1-year remission rate as a primary outcome and changes in HAQ-DI and EQ-5D scores as secondary outcomes. RESULTS: A total of 356 TNFI starters and 586 csDMARD changers were identified from each registry as unmatched cohorts, and 294 patients were included in the propensity score matched cohort. In the intention-to-treat analysis, TNFI starters had higher 1-year remission rates than csDMARD changers in both unmatched (19.1 vs. 18.4%, p < 0.01) and matched cohorts (19.7 vs. 15.0%, p < 0.01). In per protocol analysis, TNFI starters had much higher remission rates in unmatched (37.2 vs. 28.0%, p = 0.04) and matched cohorts (35.4 vs. 19.1%, p = 0.04). However, in matched cohorts, no significant differences were observed between two groups in HAQ-DI and EQ-5D scores. CONCLUSIONS: We compared the clinical effectiveness of the two treatment strategies for active RA refractory to csDMARDs. TNFI starters showed higher 1-year remission rates than csDMARD changers.

What factors affect discordance between physicians and patients in the global assessment of disease activity in rheumatoid arthritis?

OBJECTIVE: To identify the level of agreement between patients with rheumatoid arthritis (RA) and physicians in the global assessment of disease activity and to explore factors influencing their discordance. METHODS: A total of 4368 patients with RA were analyzed from the KORean Observational study Network for Arthritis (KORONA) database. Patients were divided into four subgroups according to difference from their physicians in the assessment of disease activity by substracting physician's visual analog scale (VAS) from patient's VAS as follows: positive discordance group I (10 mm ≤ discordance <25 mm), positive discordance group II (≥25 mm), concordance (<|10| mm), and negative discordance (≤ -10mm). Multinomial logistic regression analysis was performed to identify factors associated with discordance. RESULTS: Only 1350 (29.2%) patients were classified in the concordance group. Positive discordance was found in 52.3% of the patients (n = 2425), with 33.7% (n = 1563) showing marked discordance (≥25 mm). The high disease activity (OR =1.41), gastrointestinal (GI) disease (OR =1.28), pain (OR =1.12), fatigue (OR =1.07) were consistently associated with positive discordance. CONCLUSION: More than half of patients with RA thought their disease more severe than their physicians. In addition to high disease activity, pain, fatigue, and sleep disturbance or GI disease were associated with the discordance between physicians and patients with RA.

Incidence and risk factors of fractures in patients with rheumatoid arthritis: an Asian prospective cohort study.

Rheumatoid arthritis (RA) patients have high risk for osteoporosis and fracture. We aimed to identify the incidence rate and risk factors of fractures in Asian RA patients. A total of 3557 RA patients in the KORean Observational study Network for Arthritis (KORONA) were included and observed over a mean follow-up of 18 months. A fracture was assessed as total, major, or minor fractures; major fracture was defined as a vertebral or hip fracture, and the other fractures were classified as minor fractures. The standardized incidence ratio (SIR) of fracture in RA patients was calculated compared with general population, and possible risk factors for fractures were explored using multivariable logistic regression analyses. A total of 194 patients with 215 fractures were observed, and the SIR of the total fracture in RA patients was 2.2 [95 % confidence interval (CI) 1.9-2.6]. The SIRs of major and minor fractures were 1.5 (CI 1.1-2.0) and 3.0 (CI 2.5-3.7), respectively. Advanced age [odds ratio (OR) 1.03, CI 1.02-1.05, p < 0.01] and having history of prior fracture (OR 2.17, CI 1.54-3.08, p < 0.01) were risk factors for total fractures. In addition, higher HAQ increased fracture risk (OR 2.02, CI 1.05-3.89, p = 0.04), whereas the use of bisphosphonate showed protective effect for future fractures (OR 0.34, CI 0.14-0.87, p = 0.02) in patients with osteoporosis. RA patients had a 2.2-fold increased risk of fractures as compared with general population. In Asian RA patients, advanced age and history of prior fracture were the most important risk factors for new fractures.

Mapping health assessment questionnaire disability index (HAQ-DI) score, pain visual analog scale (VAS), and disease activity score in 28 joints (DAS28) onto the EuroQol-5D (EQ-5D) utility score with the KORean Observational study Network for Arthritis (KORONA) registry data.

The aim of this study was to estimate the mapping model for EuroQol-5D (EQ-5D) utility values using the health assessment questionnaire disability index (HAQ-DI), pain visual analog scale (VAS), and disease activity score in 28 joints (DAS28) in a large, nationwide cohort of rheumatoid arthritis (RA) patients in Korea. The KORean Observational study Network for Arthritis (KORONA) registry data on 3557 patients with RA were used. Data were randomly divided into a modeling set (80 % of the data) and a validation set (20 % of the data). The ordinary least squares (OLS), Tobit, and two-part model methods were employed to construct a model to map to the EQ-5D index. Using a combination of HAQ-DI, pain VAS, and DAS28, four model versions were examined. To evaluate the predictive accuracy of the models, the root-mean-square error (RMSE) and mean absolute error (MAE) were calculated using the validation dataset. A model that included HAQ-DI, pain VAS, and DAS28 produced the highest adjusted R (2) as well as the lowest Akaike information criterion, RMSE, and MAE, regardless of the statistical methods used in modeling set. The mapping equation of the OLS method is given as EQ-5D = 0.95-0.21 × HAQ-DI-0.24 × pain VAS/100-0.01 × DAS28 (adjusted R (2) = 57.6 %, RMSE = 0.1654 and MAE = 0.1222). Also in the validation set, the RMSE and MAE were shown to be the smallest. The model with HAQ-DI, pain VAS, and DAS28 showed the best performance, and this mapping model enabled the estimation of an EQ-5D value for RA patients in whom utility values have not been measured.

Drug retention and safety of TNF inhibitors in elderly patients with rheumatoid arthritis.

BACKGROUND: The concerns about the development of adverse events (AEs) in elderly RA patients as a result of age-related changes in drug metabolism and the presence of comorbid illnesses are emphasizing due to increasing prevalence of rheumatoid arthritis (RA) in old age. However, they tend to be inadequately represented in RA clinical trials because of the exclusion criteria that are commonly applied. The tolerability and safety of TNF inhibitors in elderly patients have not been also evaluated in clinical practice. This study aimed to evaluate the retention rate and safety of TNF inhibitors (TNFI) in elderly RA patients. METHODS: Total 429 RA patients (838 person-years [PYs]) treated with TNFI from a retrospective biologic DMARDs registry. Patients were divided into an elderly (age ≥60 years) and a younger group (<60 years). The drug retention rates of both groups were compared using Kaplan-Meier curves. Potential predictors of TNFI discontinuation in the elderly were examined using Cox regression analysis. The incidence rate (IR) of serious adverse events (SAEs) in the elderly group was compared to that of the young group. RESULTS: Of the patients, 24.9 % (n = 107, 212 PYs) were in the elderly group. Regarding the retention rates of TNFI in 3 years, there was no significant difference between the elderly and younger group (p = 0.33). The major cause of discontinuation in elderly patients was AE (34.3 %), whereas that was drug ineffectiveness (41.7 %) in younger patients. Age (HR 1.09, CI 1.02-1.16) was a predictor of discontinuation, while the presence of comorbidity (HR 0.37, CI 0.15-0.91) had a protective effect against drug discontinuation in the elderly. The IR of SAEs in the elderly (6.13/100 PYs) was higher than in the younger group (5.11/100 PYs). CONCLUSIONS: The retention rate of TNFI in the elderly was comparable with that in younger patients. The major cause of discontinuation in the elderly patients was AEs, while it was drug ineffectiveness in younger patients. The IR of SAEs in the elderly was higher than in the younger patients.

The frequency of and risk factors for osteoporosis in Korean patients with rheumatoid arthritis.

BACKGROUND: The aim of this study was to investigate the prevalence of osteoporosis in rheumatoid arthritis (RA) patients and to analyze the risk factors in these patients using the KORean Observational study Network for Arthritis (KORONA) database. METHODS: Among the RA patients in the KORONA who were recruited between July 2009 and December 2011, postmenopausal women with bone mineral density (BMD) results within one year from the time of KORONA enrollment were included in this study. The baseline characteristics of patients in three groups, defined by BMD results, were compared. The BMD measurement rates and prevalence of osteoporosis in the study patients were calculated in accordance with age and gender subgroups. Multivariable logistic regression analysis was used to explore the association between osteoporosis and demographics and disease-related risk factors. RESULTS: Of 1322 postmenopausal woman patients with RA in whom BMD was measured within one year of study enrollment, 619 patients (46.8 %) were in the osteoporosis group (T-score ≤ -2.5 SD). RA patients with osteoporosis had a higher frequency of previous fractures than those in other groups, especially fractures of the femur (p = 0.004) and wrist (p = 0.042). Advanced age (≥70 years; OR = 2.28, 95 % CI: 1.40-3.58), lower body mass index (<25; OR = 2.14, 95 % CI:1.52-3.02), longer disease duration (≥10 years; OR = 1.46, 95 % CI: 1.07-2.00), higher cumulative glucocorticoid dose (OR = 1.03, 95 % CI: 1.01-1.05), and higher Health Assessment Questionnaire score (OR = 1.37, 95 % CI:1.11-1.69) were independent risk factors for osteoporosis. CONCLUSION: A large percentage (90.8 %) of RA patients enrolled in the KORONA cohort had osteoporosis and osteopenia. Nevertheless, BMD measurement rates in this population remained low, despite high risk groups of fractures.

Factors Contributing to Discordance between the 2011 ACR/EULAR Criteria and Physician Clinical Judgment for the Identification of Remission in Patients with Rheumatoid Arthritis.

Remission is a primary end point of in clinical practice and trials of treatments for rheumatoid arthritis (RA). The 2011 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) remission criteria were developed to provide a consensus definition of remission. This study aimed to assess the concordance between the new remission criteria and the physician's clinical judgment of remission and also to identify factors that affect the discordance between these two approaches. A total of 3,209 patients with RA were included from the KORean Observational Study Network for Arthritis (KORONA) database. The frequency of remission was evaluated based on each approach. The agreement between the results was estimated by Cohen's kappa (κ). Patients with remission according to the 2011 ACR/EULAR criteria (i.e. the Boolean criteria) and/or physician judgment (n = 855) were divided into three groups: concordant remission, the Boolean criteria only, and physician judgment only. Multinomial logistic regression analysis was used to identify factors responsible for the assignment of patients with remission to one of the discordant groups rather than the concordant group. The remission rates using the Boolean criteria and physician judgment were 10.5% and 19.9%, respectively. The agreement between two approaches for remission was low (κ = 0.226) and the concordant remission rate was only 5.5% (n = 177). Pain affected classification in both discordant groups, whereas fatigue was associated with remission only by physician clinical judgment. The Boolean criteria were more stringent than clinical judgment. Patient subjective symptoms such as pain and fatigue were associated with discordance between the two approaches.

High-density genotyping of immune loci in Koreans and Europeans identifies eight new rheumatoid arthritis risk loci.

OBJECTIVE: A highly polygenic aetiology and high degree of allele-sharing between ancestries have been well elucidated in genetic studies of rheumatoid arthritis. Recently, the high-density genotyping array Immunochip for immune disease loci identified 14 new rheumatoid arthritis risk loci among individuals of European ancestry. Here, we aimed to identify new rheumatoid arthritis risk loci using Korean-specific Immunochip data. METHODS: We analysed Korean rheumatoid arthritis case-control samples using the Immunochip and genome-wide association studies (GWAS) array to search for new risk alleles of rheumatoid arthritis with anticitrullinated peptide antibodies. To increase power, we performed a meta-analysis of Korean data with previously published European Immunochip and GWAS data for a total sample size of 9299 Korean and 45,790 European case-control samples. RESULTS: We identified eight new rheumatoid arthritis susceptibility loci (TNFSF4, LBH, EOMES, ETS1-FLI1, COG6, RAD51B, UBASH3A and SYNGR1) that passed a genome-wide significance threshold (p<5×10(-8)), with evidence for three independent risk alleles at 1q25/TNFSF4. The risk alleles from the seven new loci except for the TNFSF4 locus (monomorphic in Koreans), together with risk alleles from previously established RA risk loci, exhibited a high correlation of effect sizes between ancestries. Further, we refined the number of single nucleotide polymorphisms (SNPs) that represent potentially causal variants through a trans-ethnic comparison of densely genotyped SNPs. CONCLUSIONS: This study demonstrates the advantage of dense-mapping and trans-ancestral analysis for identification of potentially causal SNPs. In addition, our findings support the importance of T cells in the pathogenesis and the fact of frequent overlap of risk loci among diverse autoimmune diseases.

The reliability and validity of a Korean translation of the ASAS Health Index and Environmental Factors in Korean patients with axial spondyloarthritis.

The objective of this study was to develop a Korean version of the Assessment of Spondyloarthritis International Society-Health Index/Environmental Factor (ASAS HI/EF) and to evaluate its reliability and validity in Korean patients with axial spondyloarthritis (SpA). A total of 43 patients participated. Translation and cross-cultural adaptation of the ASAS HI/EF was performed according to international standardized guidelines. We also evaluated validity by calculating correlation coefficients between the ASAS-HI/EF score and the clinical parameters. Test-retest reliability was excellent. The correlations among the mean ASAS-HI score and all tools of assessment for SpA were significant. When it came to construct validity, the ASAS HI score was correlated with nocturnal back pain, spinal pain, patients's global assessment score, the Bath ankylosing spondylitis disease activity index (BASDAI), Bath ankylosing spondylitis functional index (BASFI), Bath ankylosing spondylitis metrology index (BASMI) and EuroQoL visual analogue scale (EQ VAS) (r = 0.353, 0.585, 0.598, 0.637, 0.690, 0.430, and -0.534). The ASAS EF score was also correlated with the patient's global assessment's score, BASDAI, BASFI, BASMI, and EQ VAS score (r = 0.375, 0.490, 0.684, 0.485, and -0.554). The Korean version of the ASAS HI/EF can be used in the clinical field to assess and evaluate the state of health of Korean axial SpA patients.

A comparison of incidence and risk factors for serious adverse events in rheumatoid arthritis patients with etanercept or adalimumab in Korea and Japan.

OBJECTIVE: To compare the incidence and risk factors of serious adverse events (SAEs) in rheumatoid arthritis (RA) patients treated with etanercept (ETN) or adalimumab (ADA) between Korean and Japanese registries. METHODS: We recruited 416 RA patients [505.2 patient-years (PYs)] who started ETN or ADA from Korean registry and 537 RA patients (762.0 PY) from Japanese registry. The patient background, incidence rate (IR) of SAE in 2 years, and risk factors for SAEs were compared. RESULTS: Korean patients were younger and used more nonbiologic DMARDs, higher doses of methotrexate, and lower doses of prednisolone (PSL). The IR of SAEs (/100 PY) was higher in the Japanese registry compared to the Korean [13.65 vs. 6.73]. In both registries, infection was the most frequently reported SAE. The only significant risk factor for SAEs in Korean registry was age by decade [1.45]. In Japanese registry, age by decade [1.54], previous use of nonbiologic DMARDs ≥ 4 [1.93], and concomitant use of oral PSL ≥ 5 mg/day [2.20] were identified as risk factors for SAEs. CONCLUSIONS: The IR of SAE in Japan, especially infection, was higher than that of Korea, which was attributed to the difference of demographic and clinical characteristics of RA patients and treatment profiles.

Association of HLA-DRB1 locus with treatment response to abatacept or TNF inhibitors in patients with seropositive rheumatoid arthritis.

The strongest genetic risk factor for rheumatoid arthritis (RA) has been known as HLA-DRB1 based on amino acid positions 11, 71, and 74. This study analyzed the association between specific HLA-DRB1 locus and treatment response to abatacept or TNF inhibitors (TNFi) in patients with seropositive RA. A total of 374 Korean RA patients were treated with abatacept (n = 110) or TNFi (n = 264). Associations between HLA-DRB1 and treatment response after 6 months were analyzed using multivariable logistic regression. Seropositive RA patients with HLA-DRB1 shared epitope (SE) had a favorable response to abatacept (OR = 3.67, P = 0.067) and an inversely associated response to TNFi (OR 0.57, P = 0.058) based on EULAR response criteria, but the difference was not statistically significant in comparison to those without SE. In analyses using amino acid positions of HLA-DRB1, a significant association was found between valine at amino acid position 11 of SE and good response to abatacept (OR = 6.46, P = 5.4 × 10-3). The VRA haplotype also showed a good response to abatacept (OR = 4.56, P = 0.013), but not to TNFi. Our results suggest that treatment response to abatacept or TNFi may differ depending on HLA-DRB1 locus in seropositive RA, providing valuable insights for selecting optimal therapy.

Evaluation of TRAF6 in a large multiancestral lupus cohort.

OBJECTIVE: Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease with significant immune system aberrations resulting from complex heritable genetics as well as environmental factors. We undertook to study the role of TRAF6 as a candidate gene for SLE, since it plays a major role in several signaling pathways that are important for immunity and organ development. METHODS: Fifteen single-nucleotide polymorphisms (SNPs) across TRAF6 were evaluated in 7,490 SLE patients and 6,780 control subjects from different ancestries. Population-based case-control association analyses and meta-analyses were performed. P values, false discovery rate q values, and odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated. RESULTS: Evidence of associations was detected in multiple SNPs. The best overall P values were obtained for SNPs rs5030437 and rs4755453 (P = 7.85 × 10(-5) and P = 4.73 × 10(-5) , respectively) without significant heterogeneity among populations (P = 0.67 and P = 0.50, respectively, in Q statistic). In addition, SNP rs540386, which was previously reported to be associated with rheumatoid arthritis (RA), was found to be in linkage disequilibrium with these 2 SNPs (r(2) = 0.95) and demonstrated evidence of association with SLE in the same direction (meta-analysis P = 9.15 × 10(-4) , OR 0.89 [95% CI 0.83-0.95]). The presence of thrombocytopenia improved the overall results in different populations (meta-analysis P = 1.99 × 10(-6) , OR 0.57 [95% CI 0.45-0.72], for rs5030470). Finally, evidence of family-based association in 34 African American pedigrees with the presence of thrombocytopenia was detected in 1 available SNP (rs5030437) with a Z score magnitude of 2.28 (P = 0.02) under a dominant model. CONCLUSION: Our data indicate the presence of association of TRAF6 with SLE, consistent with the previous report of association with RA. These data provide further support for the involvement of TRAF6 in the pathogenesis of autoimmunity.

Prevalence and incidence of rheumatoid arthritis in South Korea.

Several studies of rheumatoid arthritis (RA) incidence and prevalence indicate that occurrence of the disease varies significantly among different populations. We aimed to estimate the prevalence and incidence of RA in South Korea. We used Korean National Health Insurance (NHI) claims data to estimate the prevalence of RA in 2007-2009 and the incidence of RA in 2008. On the basis of our previous validation study, the presence of RA was defined by the diagnostic code for RA with biologic or non-biologic disease-modifying anti-rheumatic drugs in the same claim in each year. To estimate the incidence of RA, we identified cases of RA in 2008 and set the 12-month period prior to 2008 as a disease-free period. Among the incident case of 2008, only patients who continued treatment in 2009 were defined as true incident case of RA in 2008. The corresponding prevalence estimates were 0.26 % (95 % CI 0.25-0.27) in 2006, 0.27 % (95 % CI 0.26-0.28) in 2007, and 0.27 % (95 % CI 0.26-0.28) in 2008. The incidence of RA in 2008 was estimated at 42/100,000 (95 % CI 29.3-54.7) in the general population of South Korea. Data gathered nationwide through the NHI yielded estimates of RA prevalence and incidence in South Korea. This study is the first report of nationwide prevalence and incidence of South Korea and those are comparable to values for other countries in Asia.