Korean Observational Study Network for Arthritis (KORONA): establishment of a prospective multicenter cohort for rheumatoid arthritis in South Korea

Prediction of osteoporosis in patients with rheumatoid arthritis using machine learning

Osteoporosis is a serious health concern in patients with rheumatoid arthritis (RA). Machine learning (ML) models have been increasingly incorporated into various clinical practices, including disease classification, risk prediction, and treatment response. However, only a few studies have focused on predicting osteoporosis using ML in patients with RA. We aimed to develop an ML model to predict osteoporosis using a representative Korean RA cohort database. The KORean Observational study Network for Arthritis (KORONA) database, established by the Clinical Research Center for RA in Korea, was used in this study. Among the 5077 patients registered in KORONA, 2374 patients were included in this study. Four representative ML algorithms were used for the prediction: logistic regression (LR), random forest, XGBoost (XGB), and LightGBM. The accuracy, F1 score, and area under the curve (AUC) of each model were measured. The LR model achieved the highest AUC value at 0.750, while the XGB model achieved the highest accuracy at 0.682. Body mass index, age, menopause, waist and hip circumferences, RA surgery, and monthly income were risk factors of osteoporosis. In conclusion, ML algorithms are a useful option for screening for osteoporosis in patients with RA.

Rheumatoid arthritis study of the Egyptian College of Rheumatology (ECR): nationwide presentation and worldwide stance

To depict the spectrum of rheumatoid arthritis (RA) in Egypt in relation to other universal studies to provide broad-based characteristics to this particular population. This work included 10,364 adult RA patients from 26 specialized Egyptian rheumatology centers representing 22 major cities all over the country. The demographic and clinical features as well as therapeutic data were assessed. The mean age of the patients was 44.8 ± 11.7 years, disease duration 6.4 ± 6 years, and age at onset 38.4 ± 11.6 years; 209 (2%) were juvenile-onset. They were 8750 females and 1614 males (F:M 5.4:1). 8% were diabetic and 11.5% hypertensive. Their disease activity score (DAS28) was 4.4 ± 1.4 and health assessment questionnaire (HAQ) 0.95 ± 0.64. The rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) were positive in 73.7% and 66.7% respectively. Methotrexate was the most used treatment (78%) followed by hydroxychloroquine (73.7%) and steroids (71.3%). Biologic therapy was received by 11.6% with a significantly higher frequency by males vs females (15.7% vs 10.9%, p = 0.001). The least age at onset, F:M, RF and anti-CCP positivity were present in Upper Egypt (p < 0.0001), while the highest DAS28 was reported in Canal cities and Sinai (p < 0.0001). The HAQ was significantly increased in Upper Egypt with the least disability in Canal cities and Sinai (p = 0.001). Biologic therapy intake was higher in Lower Egypt followed by the Capital (p < 0.0001). The spectrum of RA phenotype in Egypt is variable across the country with an increasing shift in the F:M ratio. The age at onset was lower than in other countries.

Impact of early age at menopause on disease outcomes in postmenopausal women with rheumatoid arthritis: a large observational cohort study of Korean patients with rheumatoid arthritis

OBJECTIVES

To assess the differences in clinical outcomes between patients with rheumatoid arthritis (RA) with early menopause (EM) (<45 years) and usual menopause (UM) (≥45 years) and to identify the impact of EM on longitudinal changes in RA activity and patient-reported outcomes (PROs).

METHODS

We recruited 2878 postmenopausal women with RA from the Korean Observational Study Network for Arthritis. Patients were examined at baseline and for 5 consecutive years using the Simplified Disease Activity Index (SDAI), Health Assessment Questionnaire-Disability Index (HAQ-DI) and other PROs. Generalised estimating equation (GEE) analyses were performed among patients with a baseline SDAI of >11 to evaluate the impact of EM on longitudinal changes in RA activity and PROs.

RESULTS

The EM group (n=437) was younger than the UM group (n=2441), but the RA duration was similar between the two groups. The EM group was more educated and more likely to be seronegative at enrolment. Moreover, the EM group demonstrated higher disease activity and worse PROs for global assessment, fatigue, sleep disturbance and health-related quality of life (HRQoL) (all p<0.05) at baseline. The GEE model revealed that EM significantly influenced the rate of SDAI change (β=1.265, p=0.004) after adjusting for age, RA duration, biologics use and SDAI at baseline. The EM group was also significantly associated with increased HAQ-DI scores and decreased EQ-5D-utility values during the 5-year follow-up period.

CONCLUSION

Patients with RA and EM demonstrate higher disease activity and poorer HRQoL. Furthermore, EM significantly affects the longitudinal changes in disease activity and PROs in patients with RA.

Incidence and prevalence of seropositive rheumatoid arthritis among Korean women of childbearing age: a nationwide population-based study

BACKGROUND/AIMS

Women with rheumatoid arthritis (RA) are often diagnosed with the disease during their reproductive years; however, its incidence and prevalence among women of childbearing age have not been studied. The objective of this study was to estimate the incidence and prevalence of seropositive rheumatoid arthritis (SPRA) among Korean women of childbearing age.

METHODS

Women aged 20 to 44 years with SPRA were identified from National Health Insurance Service-National Health Information Database (2009 to 2016). SPRA was defined by International Classification of Diseases, 10th revision code, M05. Incidence and prevalence were calculated per 100,000 person-years and stratified by year and age.

RESULTS

The average incidence and prevalence of SPRA from 2011 to 2016 among women of childbearing age was 24.1/100,000 person-years (95% confidence interval [CI], 23.7 to 24.5) and 105.2/100,000 person-years (95% CI, 100.9 to 109.5), respectively. The incidence increased annually from 21.0/100,000 person-years (95% CI, 20.1 to 21.9) in 2009 to 28.4 person-years (95% CI, 27.3 to 29.5) in 2016. Similarly, the prevalence increased annually from 95.7/100,000 person-years (95% CI, 93.7 to 97.6) in 2009 to 111.0 person-years (95% CI, 108.9 to 113.2) in 2015, with a slight decrease in 2016 (110.4 person-years; 95% CI, 108.2 to 112.6). The incidence and prevalence of SPRA increased with advancing age. The peak age for both incidence and prevalence of SPRA among women of childbearing age was 40 to 44 years.

CONCLUSION

The risk of SPRA is high in women during their childbearing years; this population bears a significant disease burden. This calls for special attention to this particular population group to reduce the risk and burden of this disease.

Prevalence, incidence, and risk factors of malignancy in patients with rheumatoid arthritis: a nationwide cohort study from Korea

BACKGROUND/AIMS

This study aims to evaluate the incidence of malignancy in patients with rheumatoid arthritis (RA) and to investigate risk factors for such in a nationwide, population-based cohort.

METHODS

In a large, prospective, observational cohort study, 5,077 patients with RA were enrolled from July 2009 to December 2011 and followed until February 2017. Standardized incidence ratios (SIRs) for malignancy were calculated using age- and sex-specific cancer rates in the Korean general population. Poisson regression was used to identify the risk of incident malignancy.

RESULTS

The cohort included 5,023 participants with RA contributing 16,689 person-years of follow-up. A total of 148 malignancies were recorded. The risks of stomach cancer (SIR, 0.41; 95% confidence interval [CI], 0.21 to 0.74), colon cancer (SIR, 0.13; 95% CI, 0.03 to 0.37), and lung cancer (SIR, 0.35; 95% CI, 0.14 to 0.72) were lower in RA patients than in the general population. Poisson regression modeling demonstrated that the malignancy risk was more than two-fold greater in patients with thyroid disease than in those without thyroid disease. Hydroxychloroquine therapy was associated with a reduced risk (relative risk, 0.39; 95% CI, 0.189 to 0.801) of malignancy development.

CONCLUSION

The overall risk of malignancy in patients with RA is decreased relative to in the general population. In particular, stomach, colon, and lung cancers in Korean RA patients are less common, while brain and central nervous system cancers in male RA patients are more frequent. The patients with thyroid disease and longer RA disease duration were at increased risk for developing malignancy, while hydroxychloroquine users were at lower risk.

Baseline bony erosions and time-averaged DAS28 predict discontinuation of TNF inhibitors in rheumatoid arthritis

The present study evaluated the predictive role of baseline radiographic change and disease activity on drug retention and clinical response in patients with rheumatoid arthritis (RA) treated with tumor necrosis factor inhibitor (TNFi). Korean Observational Study Network for Arthritis (KORONA) registry was evaluated to identify RA patients treated with a TNFi. Disease activity score-28 (DAS28) was evaluated at baseline and 1 year after TNFi initiation or at termination of TNFi due to inefficacy (within 1 year). The retention rate of TNFi was compared in patients with and without bony erosions. The hazard ratio (HR) for drug retention was evaluated by Cox regression analysis, as was the odds ratio (OR) for achieving remission (DAS28 < 2.6). This study included 109 RA patients, including 97 (89%) women and 30 (27.5%) with erosions, who were treated with a TNFi. Higher baseline DAS28 was negatively associated with achievement of remission (OR = 0.56, 95% CI 0.35-0.88). The TNFi retention rate was significantly lower in RA patients with than in those without erosions (p = 0.04). Factors significantly associated with drug discontinuation included the presence of erosions (HR = 2.45, 95% CI 1.08-5.51) and higher time-averaged DAS28 (HR = 2.17, 95% CI 1.47-3.20), whereas concomitant methotrexate was associated with lack of drug discontinuation (HR = 0.40, 95% CI 0.17-0.95). The presence of erosions and high time-averaged disease activity could predict poor retention of TNFi by RA patients. Higher baseline DAS28 was associated with a reduced clinical response in patients with RA.Trial registration Clinical Research Information Service of South Korea https://cris.nih.go.kr : KCT0000086, registered May 26, 2009.

Time-averaged DAS28 and HAQ predict cardiovascular disease in patients with rheumatoid arthritis: data from KORONA registry

OBJECTIVE

To evaluate the predictive role of time-averaged disease activity score (DAS)28 and Health Assessment Questionnaire (HAQ) on cardiovascular disease (CVD) events in patients with rheumatoid arthritis (RA).

METHODS

Patients with RA were recruited from 23 tertiary hospitals. Baseline and annual follow-up data of demographic, laboratory, questionnaire, RA-associated parameters, and occurrence of CVD were collected. Patients were divided into three groups according to time-averaged DAS28: 1) remission (&lt;2.6), 2) low (2.6-3.2), 3) moderate (3.2-5.1), and 4) high (&gt;5.1). Kaplan-Meier curves was performed to compare the cumulative probability of CVD. Hazard ratios of each factor on the occurrence of CVD were obtained using Cox regression analyses.

RESULTS

A total of 4,034 RA patients with 826 for remission, 938 for low, 2,002 for moderate, and 268 for high time-averaged DAS28 groups were included. Baseline age, disease duration, ESR, CRP, DAS28, and HAQ scores were higher in the high time-averaged DAS28 group. The incidence rate of CVD was 2.86, 2.71, 3.53, and 8.13 events per 1,000 person-years for the remission, low, moderate, and high time-averaged DAS28 groups, respectively. The incidence rate ratio of CVD in the high time-averaged DAS28 group were 3.01 (95% CI 1.20-8.50) when compared to low time-averaged DAS28 group. The cumulative hazard for CVD in the high time-averaged DAS28 group was significantly high (log-rank P&lt;0.01). In multivariate Cox regression analysis, age, high time-averaged DAS28, and time-averaged HAQ&gt;0.5, were positively associated with CVD events in RA patients.

CONCLUSIONS

In patients with RA, time-averaged DAS28 and HAQ could predict the occurrence of CVD.

TRIAL REGISTRATION

Clinical Research Information Service of South Korea https://cris.nih.go.kr: KCT0000086, registered May 26, 2009.

TNF inhibitors increase the risk of nontuberculous mycobacteria in patients with seropositive rheumatoid arthritis in a mycobacterium tuberculosis endemic area

The aim of this study is to examine the impact of tumor necrosis factor inhibitors (TNFI) on nontuberculous mycobacterium (NTM) infection in rheumatoid arthritis (RA) patients in a mycobacterium tuberculosis (MTB) endemic area. We selected 1089 TNFI-treated RA patients and 4356 untreated RA patients using propensity-matching analysis according to age, gender, and Charlson comorbidity index using the Korean National Health Insurance Service database from July 2009 to December 2010. Both groups were followed-up until the end of 2016 to measure the incidence of mycobacterial diseases. The incidence rate of NTM in TNFI-treated RA group was similar to those of MTB (328.1 and 340.9 per 100,000 person-years, respectively). The adjusted hazard ratio (aHR) of NTM for TNFI-treated RA compared to untreated RA was 1.751(95% CI 1.105-2.774). The risk of TNFI-associated NTM in RA was 2.108-fold higher among women than men. The age-stratified effects of TNFI on NTM development were significantly high in RA patients aged 50-65 years (aHR 2.018). RA patients without comorbidities had a higher incidence of NTM following TNFI treatment (aHR 1.742). This real-world, observational study highlights the need to increase awareness of NTM in TNFI-treated RA patients in an MTB endemic area.

Comparison of healthcare resource utilization and medical costs between patients with seropositive and seronegative rheumatoid arthritis

Objectives:

To compare healthcare utilization and medical costs between patients with seronegative (SN) and seropositive (SP) rheumatoid arthritis (RA).

Methods:

We conducted a nationwide population study using the Korean health insurance claims database in 2016. We divided patients with RA into SN and SP groups and compared healthcare utilization including medications, medical utilization, and direct medical costs for 1 year between the groups in a cross-sectional analysis. Differences in costs between patients with SPRA and SNRA were assessed using the quantile regression model. We performed longitudinal analysis using data from 2012 and 2016 to examine changes over time.

Results:

A total of 103,815 SPRA and 75,809 SNRA patients were included in the analyses. The SPRA group used significantly more methotrexate (73.2% versus 30.3%) and biologic agents (7.9% versus 2.9%) than the SNRA group. The number of RA-related outpatient visits [6.0 ± 3.7 versus 4.4 ± 4.0 times/year, standardized difference (SD) = 0.41] and annual medical costs per patient ($1027 versus $450/year, SD = 0.25) were higher in the SPRA group than the SNRA group. Quantile regression results indicated that the incremental cost of seropositivity on total medical costs of RA patients gradually increased as medical costs approached the upper quantile. The annual direct medical costs for each patient between 2012 and 2016 increased in both groups: by 25.1% in the SPRA group and 37.6% in the SNRA group.

Conclusion:

Annual RA-related direct medical costs and RA-related healthcare utilization per patient are higher in patients with SPRA than those with SNRA.

Quality Indicators for Evaluating the Health Care of Patients with Rheumatoid Arthritis: a Korean Expert Consensus

BACKGROUND

There is increasing interest in the quality of health care and considerable efforts are being made to improve it. Rheumatoid arthritis (RA) is a disease that can result in favorable outcomes when appropriate diagnosis and treatment are provided. However, several studies have shown that RA is often managed inappropriately. Therefore, the Korean College of Rheumatology aimed to develop quality indicators (QIs) to evaluate and improve the health care of patients with RA.

METHODS

Preliminary QIs were derived based on the existing guidelines and QIs for RA. The final QIs were determined through two separate consensus meetings of experts. The consensus was achieved through a panel of experts who voted using the modified Delphi method.

RESULTS

Fourteen final QIs were selected among 70 preliminary QIs. These included early referral to and regular follow-up with a rheumatologist, radiographs of the hands and feet, early initiation and maintenance of disease-modifying anti-rheumatic drug (DMARD) therapy, periodic assessment of disease activity, screening for drug safety and comorbidities, including viral hepatitis and tuberculosis before biologic DMARD therapy, periodic laboratory testing, supplementation with folic acid, assessment of the risk for cervical spine instability before general anesthesia, patient education, and specialized nurse.

CONCLUSION

These QIs can be used to assess and improve the quality of health care for patients with RA.

Epidemiology of Rheumatoid Arthritis in Korea

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterised by symmetrical involvement of the joints, associated extra-articular manifestations and functional disability. In Korea, several epidemiologic studies reporting prevalence and incidence rates of RA have been conducted using large databases such as claims databases, national surveys, prospective cohort databases or electronic health records; according to these data sources, the estimated prevalence ranged from 0.27% to 1.85%. The prevalence of extra-articular manifestations such as interstitial lung disease (ILD) and Sjögren's syndrome (SS) were also reported, but an issue of external validity of the study results persisted. In this review, we detail the epidemiology of Korean RA patients, focusing on the prevalence of RA and the frequency of systemic extra-articular manifestations including ILD and SS reported in previous studies. In addition, we discuss the current methodological issues which are inherent in Korean epidemiologic studies for patients with RA with understanding of the characteristics of each database.

Sex differences in clinical characteristics and their influence on clinical outcomes in an observational cohort of patients with rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is more prevalent in women, but sex differences remain incompletely understood. This study aimed to elucidate sex differences in clinical characteristics and their potential impact on clinical outcomes in a large Korean cohort of patients with RA.

METHODS

In total, 5376 RA patients from the KORean Observational study Network for Arthritis (KORONA) database were examined at baseline and for 3 consecutive years using the disease activity score 28 (DAS28), health assessment questionnaire (HAQ), and patient-reported outcomes (PROs). Within a subgroup with active disease (DAS28≥3.2) at baseline, sex impacts on clinical outcome during follow-up were analyzed using generalized estimating equation (GEE) models. The factors related to achieving clinical remission were analyzed using Cox-proportional hazard regression.

RESULTS

At baseline, women (n=4574) were younger and had more erosive disease and longer disease duration than men (n=802) with higher scores in DAS28, HAQ, and PROs. The prevalence of interstitial lung disease, cardiovascular disease, and diabetes in men was higher than that of women. In a RA subgroup with active disease at baseline, GEE analyses demonstrated that women RA significantly influenced the rate of change of DAS28 over time. In that group, men are associated with achieving DAS28 sustained remission and point remission.

CONCLUSIONS

Women with RA in Korea report higher levels of disease activity and PROs compared to men, whereas most comorbidities were more prevalent in men. The longitudinal change in disease activity and the rate of achieving clinical remission were found to be worse in women with RA.

A paradigm shift in studies based on rheumatoid arthritis clinical registries

Clinical research is the study of aspects of patient health or illness that are closely related to clinical practice. In the late 20th and early 21th century, outcomes for patients with rheumatoid arthritis (RA) improved dramatically due to breakthroughs in new drugs. Patient-reported outcome measures now play a significant role in the drug development process as study endpoints in clinical trials of new therapies, and this has led to increased interest in the patient's perspective, drug safety and treatment outcomes in clinical practice. In accordance with these needs, many prospective cohorts for RA patients and registries of biologic disease modifying anti-rheumatic drugs have been actively conducted in the United States and European and Asian countries. A gradual shift is taking place in the major outcomes of clinical research using these prospective cohorts and registries. This article will introduce representative registries for RA in each country set up in the early 2000s and will discuss future perspectives in clinical research on RA patients using such clinical registries.

Factors associated with time to diagnosis from symptom onset in patients with early rheumatoid arthritis

BACKGROUND/AIMS

To identify the factors associated with time to diagnosis after symptom onset in patients with early rheumatoid arthritis (RA).

METHODS

Early RA patients with ≤ 1 year of disease duration in the KORean Observational study Network for Arthritis (KORONA) database were included in this analysis. Patients were further divided into two groups according to the time to diagnosis from symptom onset: the early diagnosis group (time to diagnosis ≤ 1 year) and the late diagnosis group (time to diagnosis > 1 year). Using the multivariable regression model, we identified factors associated with early diagnosis.

RESULTS

Among 714 early RA patients, 401 patients (56.2%) and 313 patients (43.8%) were included in the early diagnosis and late diagnosis groups, respectively. The mean disease duration was 0.47 years in the early diagnosis group and 0.45 years in the late diagnosis group. In multivariable model analysis, greater age at onset (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.02 to 1.05), high school education or higher (OR, 1.68; 95% CI, 1.14 to 2.47), higher income (OR, 1.48; 95% CI, 1.05 to 2.08), and initial small joint involvement (OR, 1.42; 95% CI, 1.02 to 1.98) were factors associated with early diagnosis. At diagnosis, disease activity scores using 28 joints on diagnosis (3.81 ± 1.44 vs. 3.82 ± 1.42, p = 0.92) and functional disability (0.65 ± 0.61 vs. 0.57 ± 0.62, p = 0.07) did not different between the two groups. However, hand joint erosion on X-ray (37.8% vs. 25.6%, p < 0.01) was more common in the late diagnosis group than the early diagnosis group.

CONCLUSION

Older onset age, higher educational level and income, and initial small joint involvement were positive factors for early diagnosis of RA.

Prevalence and predictors for sustained remission in rheumatoid arthritis

OBJECTIVE

Remission is a key goal in managing rheumatoid arthritis (RA), with sustained remission as the preferred sequelae of short-term remission. However little is known about the predictors of sustained remission for patients reaching remission. Using two independent cohorts, we aimed to evaluate the prevalence and predictors for sustained remission.

METHODS

The study cohort consisted of subjects with RA from the Brigham and Women's Hospital Rheumatoid Arthritis Sequential Study (BRASS) and the Korean Observational Study Network for Arthritis (KORONA). We analyzed subjects who reached remission in 2009 with follow up data for two consecutive years. Remission was defined by the Disease Activity Score 28- (DAS28-CRP) of less than 2.6. Sustained remission was defined as three consecutive annual visits in remission. Predictors for sustained remission were identified by multivariate logistic regression analysis.

RESULTS

A total of 465 subjects were in remission in 2009. Sustained remission was achieved by 53 of 92 (57.5%) in BRASS and by 198 of 373 (53.1%) in KORONA. In multivariate analyses, baseline predictors of sustained remission were: disease duration less than 5 years [odds ratio (OR) 1.96, 95% confidence interval (95% CI) 1.08-3.58], Modified Health Assessment Questionnaire (MHAQ) score of 0 (OR 1.80, 95% CI 1.18-2.74), and non-use of oral glucocorticoid (OR 1.58, 95% CI 1.01-2.47).

CONCLUSION

More than half of RA subjects in remission in 2009 remained in remission through 2011. Short disease duration, no disability, and non-use of oral glucocorticoid at baseline were associated with sustained remission.

Clinical outcomes of patients with active rheumatoid arthritis with normal acute phase reactant values

AIM

Despite high clinical disease activity, some patients with active rheumatoid arthritis (RA) have normal acute phase reactant (APR) values. This study aimed to determine the clinical outcomes of active RA patients with normal APR values.

METHOD

Of 5376 patients with RA enrolled in the Korean observational study network for arthritis (KORONA) registry, 400 patients with disease duration of <2 years who had Clinical Disease Activity Index (CDAI) score of >2.8 at baseline, biologic-naïve, and erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) drawn at both baseline and 2-year follow-up visits were identified. Patients were grouped according to baseline APR levels: normal APRs, one APR elevated, and both APRs elevated.

RESULTS

Baseline tender and swollen joint counts, mean CDAI and Health Assessment Questionnaire-Disability Index (HAQ-DI) scores were significantly lower in the normal APRs group compared with APR-elevated groups (P < 0.0001). At 2-year follow-up, mean CDAI scores, HAQ-DI, and percentage of the patient achieving remission were not significantly different between the normal APRs group compared with the APR-elevated groups regardless of the baseline disease activity. However, in patients with baseline CDAI moderate to high disease activity, the normal APRs group less frequently required initiation of the biologic disease-modifying anti-rheumatic drugs compared with the APR-elevated groups (P = 0.044).

CONCLUSION

Active RA patients with normal APR values have milder disease presentation, but similar clinical outcomes to those with elevated APRs.

Mortality, disability, and healthcare expenditure of patients with seropositive rheumatoid arthritis in Korea: A nationwide population-based study

Background

We investigated the mortality and disability rate, as well as the healthcare expenditure, for patients with newly diagnosed seropositive rheumatoid arthritis (RA) who were followed-up for up to 10 years, compared to the general population in Korea.

Methods

We conducted a nationwide population-based study using a National Health Insurance Service-National Sample Cohort of the Korean population, consisting of 1 million individuals who submitted medical care claims between 2002 and 2013. RA was identified using as the International Classification of Diseases code M05 (seropositive RA), with prescription of any disease-modifying anti-rheumatic drug (DMARD). Our analysis was based on the data of 1655 patients with incident seropositive RA and 8275 non-RA controls. The controls were matched to the RA cohort by sex, age at the time of diagnosis, duration of follow-up, geographic region, type of social security, and household income.

Results

The most commonly used conventional synthetic DMARDs were hydroxychloroquine (71.30%) and methotrexate (69.5%), with adalimumab being the most commonly used biologic DMARD (2.54%). The mortality rate was significantly higher in the RA than the control group (incidence rate ratio [IRR] 1.29, 95% confidence interval [CI] 1.02–1.64) in the first 10 years after diagnosis. Specifically, mortality due to infectious diseases (IRR 4.41, 95% CI 1.60–12.17) and pneumonia (IRR 3.92, 95% CI 1.46–10.53) was significantly higher in the RA than control group. The disability rate was higher in the RA than control group over the first 10 years of the disease (IRR 2.27, 95% CI 1.77–2.92), which was attributed to a higher incidence of physical disability (IRR 3.81, 95% CI 2.81–5.15). Annual health expenditure was greater for the RA than the control group.

Conclusions

Therefore, the rate of mortality and disability, as well as healthcare expenditure, are higher for patients with RA over the first 10 years of the disease onset, than the general population of Korea. The use of claim data has limited the quality of information and there is a limit to the observation period, and we expect the prospective national-wide multicenter cohort for longer period to overcome these limitations.

Regulation of osteoblasts by alkaline phosphatase in ankylosing spondylitis

AIM

Ankylosing spondylitis (AS) is characterized by excessive spinal ankylosis and bone formation. Alkaline phosphatase (ALP) activity is reported to be high in AS, but little is known about the molecular relationship between ALP and AS. The aims of this study were to investigate the relevance of ALP to AS and the role of ALP in the regulation of osteoblast differentiation in AS.

METHODS

High-throughput data with accession numbers GSE73754 and GSE41038 were downloaded from the Gene Expression Omnibus. We retrospectively collected and compared the ALP levels of male patients with AS to those of sex- and age-matched healthy controls (HC) and rheumatoid arthritis (RA) patients. Total serum ALP and ALP activity were measured in the AS and RA groups. ALP gene expression and intracellular ALP activity were analyzed in microarray data from primary diseases control (Ct) and AS-bone-derived cells (BdCs) and in vitro experiments. Furthermore, the effect of ALP inhibitor was examined in both primary Ct- and AS-BdCs under osteoblast differentiation. Regulation of runt-related transcription factor 2 (RUNX2) by ALP was also analyzed.

RESULTS

Alkaline phosphatase level was higher in AS compared with RA and HC and was associated with radiograph progression. ALP expression was also enriched in the bone tissue of AS patients. Furthermore, AS-BdCs exhibited increasing ALP activity, leading to accelerated osteoblastic activity and differentiation. Intriguingly, inhibition of ALP reduced RUNX2 expression, a master transcriptional factor in osteoblasts, and differentiation status of both primary Ct- and AS-BdCs. Treatment of ALP activator or inhibitor modulated RUNX2 protein level and RUNX2 regulated ALP promoter activity, indicating a reciprocal ALP-RUNX2 positive feedback to regulate osteoblast differentiation.

CONCLUSION

Alkaline phosphatase was highly expressed in AS patients, may be involved in the ankylosis of AS, and represents a possible therapeutic target for ankylosis.

Remission rate and predictors of remission in patients with rheumatoid arthritis under treat-to-target strategy in real-world studies: a systematic review and meta-analysis

This systematic review and meta-analysis aim to evaluate the remission rate of patients with rheumatoid arthritis (RA) in real-world studies and to summarize potential predictors of remission in RA. Studies reporting remission rate in patients with RA were searched from MEDLINE, EMBASE, and Scopus databases. Two reviewers independently assessed all studies according to eligibility criteria and extracted data. Generally, observational studies reporting remission rate in adult (≥ 18 years) patients with RA were included. Quality assessments were performed using the Newcastle-Ottawa Scale. Pooled analyses of remission rate were conducted using a random-effects model and data were analyzed in subgroups to identify potential source of heterogeneity. Sensitivity analyses were performed by serially excluding each study. Potential predictors of remission were summarized. Thirty-one studies with ~ 82,450 RA patients in total were included. Using the DAS28 remission criteria, the pooled 3-, 6-, 12-, and 24-month remission rates were 17.2%, 16.3%, 21.5%, and 23.5%, respectively. Subgroup analyses showed that 11.7% and 13.8% of TNFi inadequate responders reached remission after 6- and 12-month use of non-TNFi biologics. Predictors of remission included male, higher education level, and lower baseline disease activity, while initial use of corticosteroids was negative predictors of remission. Sustained remission was rare regardless of different criteria used. Remission was a reachable target in real-world studies, while attention should also be paid to achieve sustained remission.

IL-17A induces osteoblast differentiation by activating JAK2/STAT3 in ankylosing spondylitis

BACKGROUND

IL-17A has recently emerged as a potential target that regulates the extensive inflammation and abnormal bone formation observed in ankylosing spondylitis (AS). Blocking IL-17A is expected to inhibit bony ankylosis. Here, we investigated the effects of anti IL-17A agents in AS.

METHODS

TNFα, IL-17A, and IL-12/23 p40 levels in serum and synovial fluid from patients with ankylosing spondylitis (AS), rheumatoid arthritis (RA), osteoarthritis (OA), or healthy controls (HC) were measured by ELISA. Bone tissue samples were obtained at surgery from the facet joints of ten patients with AS and ten control (Ct) patients with noninflammatory spinal disease. The functional relevance of IL-17A, biological blockades, Janus kinase 2 (JAK2), and non-receptor tyrosine kinase was assessed in vitro with primary bone-derived cells (BdCs) and serum from patients with AS.

RESULTS

Basal levels of IL-17A and IL-12/23 p40 in body fluids were elevated in patients with AS. JAK2 was also highly expressed in bone tissue and primary BdCs from patients with AS. Furthermore, addition of exogenous IL-17A to primary Ct-BdCs promoted the osteogenic stimulus-induced increase in ALP activity and mineralization. Intriguingly, blocking IL-17A with serum from patients with AS attenuated ALP activity and mineralization in both Ct and AS-BdCs by inhibiting JAK2 phosphorylation and downregulating osteoblast-involved genes. Moreover, JAK2 inhibitors effectively reduced JAK2-driven ALP activity and JAK2-mediated events.

CONCLUSIONS

Our findings indicate that IL-17A regulates osteoblast activity and differentiation via JAK2/STAT3 signaling. They shed light on AS pathogenesis and suggest new rational therapies for clinical AS ankylosis.

Chinese Registry of rheumatoid arthritis (CREDIT): II. prevalence and risk factors of major comorbidities in Chinese patients with rheumatoid arthritis

Background

Rheumatoid arthritis patients are at higher risk of developing comorbidities. The main objective of this study was to evaluate the prevalence of major comorbidities in Chinese rheumatoid arthritis patients. We also aimed to identify factors associated with these comorbidities.

Methods

Baseline demographic, clinical characteristics and comorbidity data from RA patients enrolled in the Chinese Registry of rhEumatoiD arthrITis (CREDIT) from Nov 2016 to August 2017 were presented and compared with those from five other registries across the world. Possible factors related to three major comorbidities (cardiovascular disease, fragility fracture and malignancy) were identified using multivariate logistic regression analyses.

Results

A total of 13,210 RA patients were included (80.6% female, mean age 52.9 years and median RA duration 4.0 years). Baseline prevalence rates of major comorbidities were calculated: CVD, 2.2% (95% CI 2.0–2.5%); fragility fracture, 1.7% (95% CI 1.5–1.9%); malignancy, 0.6% (95% CI 0.5–0.7%); overall major comorbidities, 4.2% (95% CI 3.9–4.6%). Advanced age was associated with all comorbidities. Male gender and disease duration were positively related to CVD. Female sex and longer disease duration were potential risk factors for fragility fractures. Ever use of methotrexate (MTX) was negatively related to baseline comorbidities.

Conclusions

Patients with rheumatoid arthritis in China have similar prevalence of comorbidities with other Asian countries. Advanced age and long disease duration are possible risk factors for comorbidities. On the contrary, MTX may protect RA patients from several major comorbidities, supporting its central role in the management of rheumatoid arthritis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1457-z) contains supplementary material, which is available to authorized users.

Impact of anti-rheumatic treatment on cardiovascular risk in Asian patients with rheumatoid arthritis

OBJECTIVES

To estimate the incidence of cardiovascular disease (CVD) in Asian patients with rheumatoid arthritis (RA) and to evaluate the impact of anti-rheumatic treatment on the development of CVD.

METHODS

A retrospective cohort of Asian patients with RA was established to identify the incidence rate (IR) of CVD in RA patients. The cohort was generated using the Korean National Healthcare claims database, which contained claims from Jan 2009 to Dec 2013. A total of 137,512 RA patients were identified; individuals with a history of CVD for 6 months or more before the index date were excluded. Nested case-control samples were drawn from the full study population with a case:control ratio of 1:4 (n = 7102 cases; n = 27,018 controls without CVD). A conditional multivariate regression model was used to evaluate the impact of anti-rheumatic treatment on the development of CVD in RA patients after matching for age, sex, RA index date, comorbidities, and drug use (e.g., antiplatelet agents and cholesterol-lowering agents).

RESULTS

The IR for development of overall CVD in RA patients was 182.1 (95% CI: 178.4-185.9) per 10,000 person-years. In models adjusted for other CVD risk factors, disease-modifying anti-rheumatic drugs (DMARDs) (OR = 0.79) were protective against CVD, and biologic DMARDs were not significantly associated with CVD risk (OR = 0.85). Corticosteroids (OR = 1.26) and NSAIDs (nonselective NSAIDs: OR = 1.32, Cox-2 inhibitors: OR = 1.31) were risk factors for CVD in RA patients.

CONCLUSIONS

The use of DMARDs is protective against CVD, while corticosteroids and NSAIDs increased the risk of CVD in RA patients.

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.

Impact of early diagnosis on functional disability in rheumatoid arthritis

BACKGROUND/AIMS

To determine whether early diagnosis is beneficial for functional status of various disease durations in rheumatoid arthritis (RA) patients.

METHODS

A total of 4,540 RA patients were enrolled as part of the Korean Observational Study Network for Arthritis (KORONA). We defined early diagnosis as a lag time between symptom onset and RA diagnosis of ≤ 12 months, whereas patients with a longer lag time comprised the delayed diagnosis group. Demographic characteristics and outcomes were compared between early and delayed diagnosis groups. Logistic regression analyses were performed to identify the impact of early diagnosis on the development of functional disability in RA patients.

RESULTS

A total of 2,597 patients (57.2%) were included in the early diagnosis group. The average Health Assessment Questionnaire-Disability Index (HAQ-DI) score was higher in the delayed diagnosis group (0.64 ± 0.63 vs. 0.70 ± 0.66, p < 0.01), and the proportion of patients with no functional disability (HAQ = 0) was higher in the early diagnosis group (22.9% vs. 20.0%, p = 0.02). In multivariable analyses, early diagnosis was independently associated with no functional disability (odds ratio [OR], 1.19; 95% confidence interval [CI], 1.01 to 1.40). In a subgroup analysis according to disease duration, early diagnosis was associated with no functional disability in patients with disease duration < 5 years (OR, 1.37; 95% CI, 1.09 to 1.72) but not in patients with longer disease duration (for 5 to 10 years: OR, 1.07; 95% CI, 0.75 to 1.52; for ≥ 10 years: OR, 0.92; 95% CI, 0.65 to 1.28).

CONCLUSIONS

Early diagnosis is associated with no functional disability, especially in patients with shorter disease duration.

Knowledge and perception of cardiovascular disease risk among patients with rheumatoid arthritis

Patients with rheumatoid arthritis are at increased risk for cardiovascular disease. The prerequisites for reducing the risk of cardiovascular disease are adequate levels of knowledge and being aware of the risk. In this study, the levels of knowledge about cardiovascular disease among patients with rheumatoid arthritis and the perception were evaluated in relation to their actual 10-year risk of cardiovascular disease. This cross-sectional study of 200 patients with rheumatoid arthritis was conducted in a university-affiliated hospital in South Korea. The patients' actual risk of cardiovascular disease was estimated using the Framingham Risk Score. The most common risk factor was physical inactivity, with 77% of the patients not engaging in regular exercise. The patients lacked knowledge about the effects of physical inactivity and anti-inflammatory medication on the development of cardiovascular disease. Misperceptions about the risk of cardiovascular disease were common, i.e., 19.5% of the patients underestimated their risk and 41% overestimated. Hypertension, diabetes, obesity, and smoking were the most prevalent among the patients who underestimated their risk, and these same patients had the lowest level of knowledge about cardiovascular disease. This study demonstrated the rheumatoid arthritis patients' lack of knowledge about the effects of physical inactivity and anti-inflammatory medications on the development of cardiovascular disease, and their misperception of cardiovascular risk was common. As a preventive measure, educational programs about cardiovascular disease should be tailored specifically for patients with rheumatoid arthritis, and behavioral interventions, including routine exercise, should be made available at the time of diagnosis.

Comorbidities of rheumatoid arthritis: Results from the Korean National Health and Nutrition Examination Survey

This study aimed to evaluate the prevalence of comorbidities in patients with rheumatoid arthritis (RA) compared with the non-RA population. The 2010-2012 Korea National Health and Nutrition Examination Survey (KNHANES), which assesses the general health status of populations in South Korea using interviews and basic health assessment, was analyzed retrospectively. Weighted prevalence and odds ratio (OR) of comorbidities were analyzed in patients with RA compared with the non-RA population. The overall weighted (n = 37,453,158) prevalence of RA was 1.5%. Patients with RA were older and more female predominant than subjects without RA. The prevalence of living in an urban area, college graduation, alcohol consumption and smoking was lower in patients with RA than non-RA. Patients with RA had more comorbidities including hypertension, dyslipidemia, myocardial infarction (MI) or angina, stoke, osteoarthritis, lung cancer, colon cancer, pulmonary tuberculosis, asthma, diabetes, depression, thyroid disease and chronic kidney disease. After adjusting socioeconomic and lifestyle characteristics, RA was associated with an increased prevalence of MI or angina (OR 1.86, 95% CI 1.17-2.96, p = 0.009), pulmonary TB (OR 1.95, 95% CI 1.24-3.09, p = 0.004), asthma (OR 1.97, 95% CI 1.05-3.71, p = 0.036), thyroid disease (OR 1.71, 95% CI 1.05-2.77), depression (OR 2.38, 95% CI 1.47-3.85, p < 0.001) and hepatitis B (OR 2.34, 95% CI 1.15-4.80, p = 0.020) compared with the non-RA population. Prevalence of solid cancer was not significantly associated with RA after adjustment.

Prevalence of co-morbidities and evaluation of their monitoring in Korean patients with rheumatoid arthritis: comparison with the results of an international, cross-sectional study (COMORA)

AIM

We designed this study to evaluate the prevalence of comorbidities, their monitoring states and association with treatment medication in Korean rheumatoid arthritis (RA) patients compared with patients from other countries.

METHODS

We analyzed 1050 RA patients from 11 Korean centers and compared them with 3520 patients from 16 other countries using an international, cross-sectional study evaluating comorbidities of RA (COMORA) database.

RESULTS

Annual evaluations of cardiovascular (CV) risk were less frequently performed in Korea (P = 0.0011). The prevalence of CV-associated morbidity was similar between Korean and international RA patients, although the proportions of current smokers, patients with a family history of CV disease, patients with hyperlipidemia, and patients with Framingham score > 20% were significantly lower in Korea (P < 0.0001 for all), and the antiplatelet agents were more optimally used in Korea (P = 0.0004). Prostate cancer screening was less frequently performed compared to other countries (P < 0.0001). Less than 10% of Korean RA patients were given influenza and pneumococcal vaccinations according to current recommendations.

CONCLUSIONS

There are differences in the prevalence of comorbidities and monitoring states of the risk factors between patients in Korea and in other countries. The prevalence of CV morbidity was similar between the two groups although the prevalence of CV risk factors was significantly low in Korea, suggesting that rheumatologists in Korea need to pay more attention to yearly CV risk monitoring, in addition to the screening of malignancy and vaccination of RA patients against infectious diseases.

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.

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.

Characteristics of rheumatoid arthritis and its association with major comorbid conditions: cross-sectional study of 502 649 UK Biobank participants

Introduction

To characterise the detailed phenotypic and comorbid characteristics of participants with rheumatoid arthritis (RA) in the large population-based UK Biobank, thereby enabling future longitudinal analyses.

Methods

We undertook a cross-sectional study using baseline data from the unique UK Biobank resource (n=502 649). RA was based on self-report, and type of medication was used as a proxy measure of valid diagnosis. Participants with and without RA were compared in terms of sociodemographic, lifestyle and other disease-related risk factors. Logistic regression models were used to determine whether participants with RA were more likely to report comorbid conditions, and whether this varied by RA severity. The models were adjusted for potential confounders and lifestyle risk factors.

Results

At baseline, 5657 (1.13%) eligible UK Biobank participants reported RA of whom 2849 (0.57%) had medically treated RA (median duration=10 years). Prevalence was significantly higher among female, South Asian and socioeconomically deprived participants. Participants with RA were significantly more likely to report diabetes (covariate-adjusted OR 1.18, 95% CI 1.06 to 1.32, p<0.01), hypertension (OR 1.19, 95% CI 1.21 to 1.27, p<0.001) and cardiovascular disease (OR 1.52, 95% CI 1.39 to 1.67, p<0.001).

Conclusions

UK Biobank provides extensive data concerning RA population-level comorbidity and risk factors. The frequency, distribution and characteristics of participants reporting RA in UK Biobank are largely consistent with other studies. It provides a unique opportunity to interrogate biomarkers, genetic data, detailed imaging and linkage to clinical records at the population level across primary and secondary care.

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.

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.

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.

The dynamic evolution of rheumatology in Korea

Rheumatology was first recognized as a distinct clinical specialty in Korea just 35 years ago. Young professors who were trained in rheumatology in the USA and afterwards returned to Korea contributed substantially to advances in rheumatology clinical practice, educational programmes and research activities. They also established the Korean Rheumatism Association, later renamed the Korean College of Rheumatology. These young rheumatologists had a major role not only in raising the level of clinical and scientific activities, but also in promoting academic exchanges around the Asia-Pacific region, the USA and Europe. Subsequently, Korea's rapid economic growth and high education level enabled rheumatology to advance rapidly. Today, continued efforts are required to raise the standard of clinical and basic research, to optimize clinical practice with regard to new biologic agents, to exploit personalized and targeted therapies for the rheumatic diseases, and to meet the medical demands of Korea's ageing society.

Factors Associated with the Use of Complementary and Alternative Medicine for Korean Patients with Rheumatoid Arthritis

Objective.

Rheumatoid arthritis (RA) is a chronic autoimmune disease that is often painful and debilitating. Patients with RA are increasingly receiving complementary and alternative medicine (CAM). We aimed to identify the patient characteristics and disease-specific factors associated with Korean patients with RA who decide to start treatment with CAM.

Methods.

Among the total 5371 patients with RA in the KORean Observational study Network for Arthritis (KORONA), 2175 patients who had no experience with CAM were included in our study. In our study, we assessed the frequency of new incident CAM use, its patterns, and the predictive factors of new CAM use.

Results.

Of the 2175 patients, 229 patients (10.5%) newly started receiving CAM within a year of enrolling in the cohort. Of those who started treatment with CAM, 17.0% received only herbal medicine, 54.6% only acupuncture treatments (7.0% used a combination of both), and 21.4% “Other” (e.g., physical therapy and placental extract injections). Women (OR 1.89, 95% CI 1.13–3.14) and patients with depression (OR 3.52, 95% CI 1.65–7.50) were significantly more likely to be treated with CAM. Regarding household types, patients who lived in an extended family (OR 1.78, 95% CI 1.08–2.95) or as part of a couple (OR 1.55, 95% CI 1.07–2.24) were more likely to be treated with CAM than patients living in a nuclear family.

Conclusion.

Our study found, within a year, an incidence rate of 10.5% for new CAM use among patients with no previous experience with CAM. Sex, depression, and household type were significantly associated with new CAM use.

Inconsistent treatment with disease-modifying antirheumatic drugs: a longitudinal data analysis

OBJECTIVE

Current recommendations advocate treatment with disease-modifying antirheumatic drugs (DMARD) in all patients with active rheumatoid arthritis (RA). We investigated the frequency of and reasons for inconsistent DMARD use among patients in a clinical rheumatology cohort.

METHODS

Patients in the Brigham Rheumatoid Arthritis Sequential Study were studied for DMARD use (any or none) at each semiannual study timepoint during the first 2 study years. Inconsistent use was defined as DMARD use at ≤ 40% of study timepoints. Characteristics were compared between inconsistent and consistent users (> 40%), and factors associated with inconsistent DMARD use were determined through multivariate logistic regression. A medical record review was performed to determine the reasons for inconsistent use.

RESULTS

Of 848 patients with ≥ 4 out of 5 visits recorded, 55 (6.5%) were inconsistent DMARD users. Higher age, longer disease duration, and rheumatoid factor negativity were statistically significant correlates of inconsistent use in the multivariate analyses. The primary reasons for inconsistent use identified through chart review, allowing for up to 2 co-primary reasons, were inactive disease (n = 28, 50.9%), intolerance to DMARD (n = 18, 32.7%), patient preference (n = 7, 12.7%), comorbidity (n = 6, 10.9%), DMARD not being effective (n = 3, 5.5%), and pregnancy (n = 3, 5.5%). During subsequent followup, 14/45 (31.1%) inconsistent users with sufficient data became consistent users of DMARD.

CONCLUSION

A small proportion of patients with RA in a clinical rheumatology cohort were inconsistent DMARD users during the first 2 years of followup. While various patient factors correlate with inconsistent use, many patients re-start DMARD and become consistent users over time.

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.

Patterns of disease-modifying antirheumatic drug use in rheumatoid arthritis patients after 2002: a systematic review

OBJECTIVE

To report and synthesize patterns of disease-modifying antirheumatic drug (DMARD) use reported in observational studies of patients with established and early rheumatoid arthritis (RA) after publication of the American College of Rheumatology guidelines promoting universal DMARD use.

METHODS

We searched PubMed for full-length articles in English published between January 1, 2002 and October 1, 2012 that examined DMARD use. The data abstracted from articles included the patient characteristics, country of study, time period studied, patient source, and treating physician type. Study quality was assessed using a modified Newcastle-Ottawa Quality Assessment Scale.

RESULTS

We reviewed 1,287 abstracts; 98 full-length articles were selected for additional review and 27 studies describing 28 cohorts of patients were included. Twelve studies described data from cohorts of patients with established RA, and DMARD use in this group of studies ranged from 73-100%. Five studies described data from patients sourced through administrative data and demonstrated consistently lower DMARD use, ranging from 30-63%. Three studies conducted population-based surveys to define cases of RA where DMARD use ranged from 47-73%. Eight studies investigated patients with early RA. DMARD use among patients followed by rheumatologists ranged from 77-98%, whereas DMARD use reported for patients seen by a mix of physicians was significantly lower (39-63%).

CONCLUSION

DMARD use in studies from RA cohorts or registries (in which patients were followed by rheumatologists) ranged from 73-100%, compared with 30-73% in studies from administrative data or population-based surveys (in which patients were not necessarily receiving rheumatology subspecialty care).

Development of an algorithm for identifying rheumatoid arthritis in the Korean National Health Insurance claims database

This study aimed to develop an identification algorithm for validating the International Classification of Diseases-Tenth diagnostic codes for rheumatoid arthritis (RA) in the Korean National Health Insurance (NHI) claims database. An individual copayment beneficiaries program for rare and intractable diseases, including seropositive RA (M05), began in South Korea in July 2009. Patients registered in this system pay only 10 % of their total medical costs, but registration requires an official report from a doctor documenting that the patient fulfills the 1987 ACR criteria. We regarded patients registered in this system as gold standard RA and examined the validity of several algorithms to define RA diagnosis using diagnostic codes and prescription data. We constructed nine algorithms using two highly specific prescriptions (positive predictive value >90 % and specificity >90 %) and one prescription with high sensitivity (>80 %) and accuracy (>75 %). A total of 59,823 RA patients were included in this validation study. Among them, 50,082 (83.7 %) were registered in the individual copayment beneficiaries program and considered true RA. We tested nine algorithms that incorporated two specific regimens [biologics and leflunomide alone, methotrexate plus leflunomide, or more than 3 disease-modifying anti-rheumatic drugs (DMARDs)] and one sensitive drug (any non-steroidal anti-inflammatory drug (NSAID), any DMARD, or any NSAID plus any DMARD). The algorithm that included biologics, more than 3 DMARDs, and any DMARD yielded the highest accuracy (91.4 %). Patients with RA diagnostic codes with prescription of biologics or any DMARD can be considered as accurate cases of RA in Korean NHI claims database.

Interaction of HLA-DRB1*09:01 and *04:05 with smoking suggests distinctive mechanisms of rheumatoid arthritis susceptibility beyond the shared epitope

OBJECTIVE

Although HLA-DRB1 shared epitope (SE) alleles and HLA-DRB1*09:01 have repeatedly been shown to be associated with susceptibility to rheumatoid arthritis (RA), the effect of each allele on levels of anticyclic citrullinated peptide autoantibodies (anti-CCP) and interaction with cigarette smoking in RA remains to be fully defined. We investigated whether HLA-DRB1 risk alleles influence anti-CCP levels and whether each allele interacts with smoking in anti-CCP-positive or -negative RA.

METHODS

All patients with RA (n = 1924) and controls (n = 1119) were Korean. The HLA-DRB1 4-digit genotyping was performed by standard PCR-sequencing based typing method. OR and biologic interactions as departures from additivity or multiplicity were analyzed by logistic regression.

RESULTS

SE alleles were significantly associated with increased anti-CCP levels. Conversely, HLA-DRB1*09:01 was associated with reduced levels, in both SE-positive and SE-negative patients. Each of SE alleles interacted significantly with smoking, whereas HLA-DRB1*09:01 did not. Interactions between the 2 most significant risk alleles, HLA-DRB1*04:05 and HLA-DRB1*09:01, (attributable proportion = 0.68, 95% CI 0.46-0.89, multiplicity p = 0.012) significantly increased RA susceptibility regardless of anti-CCP and smoking status. Smoking increased the risk for RA by significant interaction with the heterozygote HLA-DRB1*04:05/*09:01.

CONCLUSION

HLA-DRB1*09:01 differs from SE alleles with regard to anti-CCP levels and interaction with smoking, suggesting a distinct mechanism of HLA-DRB1*09:01 in the pathogenesis of RA that may bypass anti-CCP formation. Also, a significant increase of the HLA-DRB1*04:05/ *09:01 heterozygote in RA susceptibility may be attributable to the synergistic contribution of 2 different pathways in which 2 alleles participate independently.

Smoking, the HLA-DRB1 shared epitope and ACPA fine-specificity in Koreans with rheumatoid arthritis: evidence for more than one pathogenic pathway linking smoking to disease

OBJECTIVES

Data from North European rheumatoid arthritis (RA) populations has suggested a particularly strong association of gene-environment interaction between smoking and HLA-DRB1 shared epitope (SE) with antibodies to citrullinated α-enolase (CEP-1) and vimentin (cVim) peptides. We investigated this further by examining anticitrullinated peptide/protein antibody (ACPA) fine specificity in a Korean cohort, where there are notable differences in the RA-associated HLA-DRB1 alleles.

METHODS

Antibodies to fibrinogen (cFib), α-enolase (CEP-1) and vimentin (cVim) peptides and cyclic citrullinated peptide (CCP) were measured in 513 cases. The Mann-Whitney U test was used to compare antibody levels. Logistic regression generated ORs for RA in a case-control analysis with 1101 controls. Association of ACPA status and erosion in patients with RA was examined by logistic regression.

RESULTS

Anti-CCP, CEP-1, cVim and fibrinogen peptides were found in 86.7%, 63.9%, 45.5% and 74.7%, respectively. The number of ACPA and their levels were associated with SE, with evidence of a gene-dosage effect. There was a particular association of smoking with levels of anti-CEP-1. However, a gene-environment interaction was associated with all the ACPA positive subgroups, albeit the highest OR was seen with the anti-CCP+/cVim+ subset. In the absence of SE, smoking only conferred risk for anti-CCP negative subsets. The presence of erosions was not associated with the number of positive ACPA or specificity.

CONCLUSIONS

The SE governed the magnitude and diversity of the ACPA response, but its interaction with smoking did not exclusively segregate with any of the ACPA specificities studied here. Smoking was associated with RA by SE-dependent and independent effects.

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.

Do patients with elderly-onset rheumatoid arthritis have severe functional disability?

OBJECTIVE

To identify the clinical features of elderly-onset rheumatoid arthritis (EORA) and their impact on disease outcome.

METHODS

A total of 3169 rheumatoid arthritis (RA) patients were recruited as part of the Korean Observational Study Network for Arthritis, the nationwide cohort of South Korea. Patients were stratified according to age at disease onset: <40 years (younger age-onset RA, n = 1167), between the ages of 40 and 59 (middle-aged-onset RA, n = 1516), and ≥60 years (EORA, n = 486). To evaluate the significance of differences in clinical features among these 3 groups, we performed analysis of variance (anova) and the χ(2) test. We used multivariable logistic regression analysis to examine the association of onset age with functional disability measured with Health Assessment Questionnaire-Disability Index (HAQDI).

RESULTS

EORA patients were associated with high HAQDI (≥1) in bivariable analysis [odds ratio (OR) 1.36, confidence interval (CI) 1.04-1.77]. However, in multivariable analysis, not elderly onset but patients' age, female gender, high disease activity, disease duration over 10 years, and comorbidity with cardiovascular disease were associated with high HAQDI. Only in a predefined subgroup with disease duration <10 years, elderly onset was an independent influencing factor for the functional disability of RA patients (OR 3.04, CI 1.85-5.67: disease duration of <5 years, OR 3.07, CI 1.64-5.74: disease duration of 5 to 10 years).

CONCLUSIONS

Disease onset in older age was associated independently with functional disability of RA patients who have relatively short disease duration.