Prevalence and incidence of rheumatoid arthritis in South Korea

National trends in rheumatoid arthritis and osteoarthritis prevalence in South Korea, 1998-2021

Studies on the trends in the prevalence of rheumatoid arthritis (RA) and osteoarthritis (OA) are limited, particularly during the COVID-19 pandemic. This study aimed to analyze the temporal trend of RA and OA in South Korean adults from 1998 to 2021, including the COVID-19 pandemic period. The Korea National Health and Nutrition Examination Survey (KNHANES) data on adults aged ≥ 19 years were analyzed to investigate the prevalence of RA and OA from 1998 to 2021. The prevalence trends were compared by the years, and βdiff (β difference) was calculated. Odds ratios (ORs) were computed for each disease to examine changes in disease prevalence before and during the pandemic in order to determine the impact of the pandemic on disease prevalence. Among 163,221 Korean adults, the prevalence of RA and OA showed a steady decrease from 2005 (RA: from 1.91% in 2005-2007 to 1.55% in 2016-2019 and OA: from 9.75% in 2005-2007 to 8.27% in 2016-2019), but there was a slight increased after the onset of the COVID-19 pandemic (RA: from 1.23% in 2020 to 1.36% in 2021 and OA: from 8.04% in 2020 to 8.27% in 2021). Vulnerable groups, including participants aged ≥ 60 years (versus 19-60 years, ratio of ORs: 1.222; 95% CI 1.011-1.477), urban residents (ratio of ORs: 1.289; 95% CI 1.007-1.650), and participants with higher education level (ratio of ORs: 1.360; 95% CI 1.119-1.653) showed higher ORs of OA, whereas no particularly vulnerable population was observed for RA. Our findings provide an insight into the long-term trends of RA and OA among adult population and highlight a novel perspective on the impact of COVID-19 on disease prevalence.

Joint Replacement Surgery in Patients with Rheumatoid Arthritis in South Korea: Analysis of a Large National Database

BACKGROUND

We aimed to investigate the current trend of joint replacement surgery incidence in patients with rheumatoid arthritis (RA) in South Korea and to compare the incidence of joint replacement surgery in each affected joint.

METHODS

We performed this big data analysis to investigate the current trend of joint replacement surgery incidence in patients with RA in South Korea and to compare the incidence of joint replacement surgery in each affected joint. This retrospective study was based on data from the Korea National Health Insurance claims database.

RESULTS

The prevalence of RA increased every year (0.13% in 2008, 0.25% in 2016). The number of newly diagnosed patients increased from 29,184 in 2010 to 38,347 in 2016. The incidence rate of joint replacement surgery in patients with RA increased from 0.72% in 2010 to 4.03% in 2016. The knee (68.3%) was the most commonly replaced joint. The relative risk (RR) of additional joint replacement surgery was highest for the shoulder joint (RR,1.454; 95% confidence interval, 0.763-2.771). The median time from diagnosis to surgery was the shortest in the elbow joint (379 days) and the longest in the shoulder joint (955 days). The median time for each joint was short in order of the elbows, ankles, hips, knees, and shoulders (p < 0.01).

CONCLUSIONS

The most frequently and initially replaced joints were different, but the prevalence and incidence of RA, as well as those of joint replacement surgery, have recently increased in South Korea. Joint replacement surgery in RA was the highest for the knee joint. The median time from diagnosis to surgery was shortest for the elbow, followed by the ankle, hip, knee, and shoulder. Regardless of whether patients are symptomatic, evaluation of large joints such as the knee, elbow, ankle, and hip should be considered from an early stage.

Treatment Sequence After Initiating Biologic Therapy for Patients With Rheumatoid Arthritis in Korea: A Nationwide Retrospective Cohort Study

Objective

To evaluate treatment patterns and healthcare resource utilization (HCRU) after initiating biologic disease-modifying antirheumatic drugs (bDMARDs) in Korean patients with rheumatoid arthritis (RA).

Methods

Patients newly diagnosed with RA in 2014 were identified and followed up on using the Korean National Health Insurance Database until 2018. The initial line of therapy (LOT) or LOT1 included patients treated with conventional DMARDs (cDMARD). Patients who started a bDMARD were assigned to LOT2 bDMARD. Those who moved from a bDMARD to a Janus kinase inhibitor were assigned to LOT3. Analyzed outcomes were treatment patterns and HCRU in LOT2 bDMARD.

Results

The most prescribed initial bDMARD was a tumor necrosis factor inhibitor. Seventy-five percent of patients had changes in treatment after starting a bDMARD, such as addition/removal or switch of a DMARD, and transition to LOT3. For the first and second changes in LOT2 bDMARD, adding a cDMARD to a bDMARD was more common than switching to another bDMARD (7.98% vs. 2.93% for the first change, and 17.10% vs. 6.51% for the second change). Tocilizumab was the most common bDMARD that was switched to. Forty-eight percent of patients had at least one hospitalization after initiating bDMARDs. Of these patients, 64.3% were admitted due to RA-related reasons.

Conclusion

This real-world study provides information on treatment characteristics of RA patients in Korea after starting a bDMARD. In contrary to guidelines, cDMARD addition was more often than bDMARD switches in daily clinical practice.

The prevalence of rheumatoid arthritis in Western Australia

BACKGROUND

Rheumatoid arthritis (RA) is the most common form of autoimmune arthritis, but the prevalence in Australia is unknown. We estimated RA period prevalence and identified factors associated with frequent RA hospitalisations, using linked administrative health and state-specific Australian Pharmaceutical Benefits Scheme (PBS) datasets in Western Australia (WA) from 1995 to 2014.

METHODS

This was a longitudinal population-based cohort study using two independent datasets to identify prevalent RA patients. RA prevalence was calculated per 1000 hospital separations and biological therapy users. RA patients were identified in the WA linked health dataset using ICD codes 714.0-714.9 and M05.00-M06.99. Dispensing data on biological therapy for RA were obtained from PBS records and converted to defined daily doses /1000 population/day. Multivariable logistic regression was used to analyse factors associated with frequent RA hospitalisations (> 2/year), controlling for sex, age, and geographic locations. Potential interactions were assessed using logistic regression in a stepwise approach.

RESULTS

A total of 17,125 RA patients had 50,353 hospital separations between 1995 and 2014, averaging three hospitalisations per patient over 20 years. The RA period prevalence was 3.4 per 1000 separations (0.34%; 95% CI 0.33-0.34), while the RA period prevalence based on biological therapy use was 0.36% (95% CI 0.35-0.37). The corrected RA prevalence based on biological therapy usage was 0.36% (95% CI 0.35-0.37) for the 2005-2009 and increased to 0.72% (95% CI 0.70-0.74) in 2010-2014 period. Associated factors for frequent RA hospitalisations were being female [1.21 (95% CI 1.15-1.26)], aged 60-69 years [4.45 (95% CI 3.74-5.30)], living in rural areas [1.12 (95% CI 1.02-1.24)]. The odd ratio of interaction between these associated factors was 1.34 (95% CI 1.16-1.55).

CONCLUSION

The minimal prevalence of RA in Western Australia is 0.34-0.36%, which falls within the literature range. Older female RA patients in rural were more likely to be hospitalised, suggesting unmet primary care for needs.

Potential Cancer Risk in Patients with Rheumatoid Arthritis: A Longitudinal Korean Population-Based Analysis

The potential link between rheumatoid arthritis (RA) and cancer incidence needs to be validated due to inconsistent results between Asian and Western countries. We explored the long-term association of RA with the overall and organ-specific cancer incidence using nationwide population data. This longitudinal follow-up study (2002–2015) included 3070 patients with RA and 12,280 controls (1:4 propensity score-matched for sex, age, residence, and income) from the Korean National Health Insurance Service-Health Screening Cohort database. A Cox proportional hazard model estimated the hazard ratio for malignancy following adjusting for covariates. Despite the similar overall cancer incidence between RA and control groups, differences in the incidence of organ-specific cancers were noted: the RA group had a 1.63-fold greater likelihood for lung cancer (95% confidence interval 1.11–2.40). In the sex-stratified subgroup analyses, the male RA patients exhibited higher odds of lung and thyroid cancer but a lower probability for colorectal cancer; no such associations were detected in either female patients with RA or age subgroups. In summary, the higher likelihood for lung cancer in Korean RA patients, especially thyroid and lung cancer in male RA patients, seems to be characteristic, which needs to be carefully monitored.

Silencing CoREST inhibits the viability and migration of fibroblast‑like synoviocytes in TNF‑α‑induced rheumatoid arthritis

Fibroblast-like synoviocytes (FLSs) have functions in the pathogenesis of rheumatoid arthritis (RA) through the onset of synovitis, the growth of pannus and the destruction of cartilage and bone. The significant increase in the proliferation, migration and invasion of FLSs induces the onset and advancement of RA. To date, the exact function of corepressor element-1 silencing transcription factor (CoREST) in RA remains unclear, but its expression has been determined in RA synovial tissues. In this study, the effects of CoREST were investigated in a TNF-α-induced FLS activation model. Following the silencing of CoREST expression with small interfering (si)RNA, the viability and migration of FLSs were evaluated. Furthermore, the possible molecular mechanisms were explored by detecting the expression of key factors, including matrix metalloproteinases (MMPs), lysine-specific histone demethylase 1 (LSD1) and associated cytokines, via reverse transcription-quantitative PCR and western blotting. CoREST expression increased not only in the RA synovial tissues, but also in the TNF-α-induced FLS activation model. Following the silencing of CoREST in the FLSs treated with TNF-α, cell viability was inhibited, and the migratory capacity of FLSs was suppressed, which was accompanied by the reduced expression of MMP-3 and MMP-9. The expression of LSD1 was also downregulated. There was a notable decrease in the synthesis of interferon-γ and interleukin (IL)-17, while IL-10 expression was increased. The knockdown of CoREST inhibited the viability and migration of FLSs stimulated with TNF-α. Thus, the suppression of CoREST may have crucial roles in the occurrence and development of RA.

Incidence and prevalence of pressure ulcers in hospitals: 10-year cohort study

OBJECTIVE

Pressure ulcers (PUs) are a serious problem in patients with multiple comorbidities and are associated with a longer duration of hospital stay and higher medical costs. The aetiology and rate of PU occurrence in South Korea remains unclear. Therefore, we aimed to determine the incidence, prevalence, mortality and common comorbidities of hospitalised patients with PUs in the South Korean healthcare system.

METHOD

A 10-year cohort study using the healthcare insurance reimbursement claims from the South Korean National Health Insurance System database. Patients diagnosed with a PU on admission to hospital [ICD-10: L89 + procedure code] between January 2002 and December 2016 were included and their comorbidities evaluated. Patients <20 years of age and recurrent PU cases were excluded.

RESULTS

Incidence, prevalence, survival rate and risk factors related to survival rate of patients with PUs were determined. The study population in 2006 was 36,195,121 (all patients admitted to hospital that year), which changed yearly because of the inclusion of additional patients who met the study inclusion criteria, and removal of patients who had died during the year. Standardised PU incidence rate decreased from 17.1 in 2006 to 14.9 in 2015 per 10,000 people. Standardised PU prevalence also showed a slightly decreasing trend from 20.2 in 2006 to 18.9 in 2015 per 10,000 people.

CONCLUSION

This findings of this 10-year study showed that incidence and prevalence of PUs markedly increased with age after the seventh decade. Incidence of PUs increased in patients with pneumonia, cerebral infarction, sepsis, femoral neck fracture and malignant neoplasm of the bronchus. Patients with femoral neck fracture and cerebral infarction showed a higher rate of survival than those with other high-risk comorbidities.

Association between previous rheumatoid arthritis and COVID-19 and its severity: a nationwide cohort study in South Korea

OBJECTIVES

The prevalence of rheumatoid arthritis (RA) among patients with COVID-19 and the association between RA and the outcome of COVID-19 remain unclear. We aimed to compare the prevalence of RA between participants with and without COVID-19; we then analysed the association between the presence of RA and the severity of COVID-19.

DESIGN

A cross-sectional study.

SETTING

Data from a nationwide COVID-19 cohort database by the Korea National Health Insurance Corporation were used.

PARTICIPANTS AND INTERVENTIONS

A total of 8070 patients with COVID-19 (1 January 2020 through 4 June 2020) were matched with 32 280 control participants with regard to age, sex and income. Patients with COVID-19 were confirmed by SARS-CoV-2 PCR and controls were collected from the database. RA was confirmed using the diagnostic code (International Classification of Disease, Tenth Revision) and medication claim codes. Conditional/unconditional logistic regression was applied to analyse the association between RA and COVID-19.

PRIMARY OUTCOME AND SECONDARY OUTCOME

Laboratory confirmation of SARS-CoV-2 infection was defined as the primary outcome. The secondary outcome was severe COVID-19 defined as a history of intensive care unit admission, invasive ventilation or death.

RESULTS

The prevalence of RA in the COVID-19 (0.4%, 35/8070) and control (0.4%, 121/32,280) groups did not differ (p=0.446). After adjusting for underlying diseases, no association between RA and COVID-19 was observed (adjusted OR=1.14, 95% CI: 0.78 to 1.67) and COVID-19 severity was not associated with RA (adjusted OR=0.62, 95% CI: 0.14 to 7.29). The overall mortality rate was 2.9% (237/8070) and RA was not significantly associated with mortality (adjusted OR=1.64, 95% CI: 0.33 to 8.15).

CONCLUSION

We did not find an association between the presence of RA and COVID-19. In addition, RA was not associated with the severity of COVID-19.

Epidemiological Trends of Rheumatoid Arthritis and PADI4, PTPN22, and HLA-DRB9 Genes Distribution in the Kazakhstan Population

BACKGROUND: The prevalence of rheumatoid arthritis (RA) is 1% in the global population. The lack of epidemiological studies in developing countries makes it difficult to obtain a complete global epidemiological picture of RA. RA develops due to the interaction of multiple genetic and environmental factors, though the contribution of these factors to the various disease occurrence seen in different populations is unclear. AIM: The aim of our study was to analyze the dynamics of the general prevalence and incidence of RA among the population of Kazakhstan in 2017–2019 as well as to investigate the three most common single-nucleotide polymorphisms (SNP) of RA in the Kazakhstan population. METHODS: The analysis of statistical data on Form 12 “On the health of the people and the health care system” was carried out. Prevalence and incidence rates were calculated according to generally accepted rules. Demographic data for the Republic of Kazakhstan were obtained from the official website stat.gov.kz. Our study included 70 RA patients and 113 control subjects. Blood samples were collected and genotyped for peptidylarginine deiminase 4 (PADI4), protein tyrosine phosphatase 22, and human leukocyte antigen (HLA)-DRB9 SNPs by reverse transcription polymerase chain reaction. RESULTS: The prevalence of RA in Kazakhstan in 2017–2019 was 0.36–0.38%, with an incidence rate of 0.085–0.087%, which can be comparable to data of other countries in Central Asia. The allele and genotypes frequency analyses were carried out between patients and controls. The HLA-DRB9 showed significant association of the G allele odds ratio (OR) 1.96 (95% confidence interval [CI]: 1.252–3.081), p= 0.0025 and G/G genotype OR = 3.67 (95% CI: 1.58–8.54), p = 0.00162 with RA in our sample. Strong association between anti-citrullinated protein antibody (ACPA) profile and PADI4 (OR 12.19 [95% CI: 2.19–67.94], p = 0.00115) was found. CONCLUSION: There was an increase in RA prevalence with age among females and a higher crude prevalence and incidence of RA in the southern regions of Kazakhstan. HLA-DRB9 prevailed in Kazakhstani patients with RA, PADI4 showed association with ACPA-positive RA. Further studies on larger samples are required to confirm our obtained results.

Real-World Safety and Effectiveness of Golimumab in Rheumatic Diseases: Post-Marketing Surveillance in Korea

Introduction

Golimumab is a human monoclonal antibody that inhibits tumor necrosis factor-α (TNF-α). Inhibition of TNF-α by golimumab inhibits the inflammatory response, thereby modulating the immune response in immune-mediated inflammatory diseases. Although the efficacy of golimumab has been demonstrated in randomized controlled trials (RCTs), various patient populations, such as those at high risk of infection, including those with latent tuberculosis and various comorbidities, or on co-administered medications, were excluded from the RCTs. Therefore, safety cannot be sufficiently evaluated by RCTs in the patient group with heterogenous characteristics. The aim of this study was to assess the safety and effectiveness of golimumab in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondyloarthritis (AS) in a real-world setting in Korea.

Methods

We conducted an open-label, prospective, non-interventional study as post-marketing surveillance. Safety was evaluated by collecting and recording adverse events, and effectiveness was evaluated by assessing disease activity using DAS28-CRP, DAS28-ESR, ACR20, and ASAS20 outcome measures. Multiple logistic regression was performed to identify factors associated with the incidence of adverse events, and changes in disease activity scores from baseline were analyzed using the Wilcoxon signed-rank test.

Results

A total 673 patients were enrolled, of whom 621 were included in the safety analysis. During the study, 97 adverse drug reactions (ADRs) were reported in 62 patients (10.0%). The most frequently reported ADRs were related to infection, including nasopharyngitis (0.8%), upper respiratory tract infection (0.6%), and herpes zoster (0.5%). The mean (± standard deviation) changes from baseline in global disease activity at weeks 12 and 24 were − 3.37 ± 2.529 and − 3.68 ± 2.404, respectively, with statistical significance. In those patients with RA, 72.5 and 47.0% of individuals had a good response based on DAS28-CRP and DAS28-ESR outcomes at week 24. At week 24, 71.4% of patients with PsA had an ACR20 response and 72.9% of patients with AS had an ASAS20 response.

Conclusion

In the real-world setting, golimumab was safe and effective in Korean patients with RA, PsA, and AS.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-021-00352-6.

Bidirectional association between migraine and rheumatoid arthritis: two longitudinal follow-up studies with a national sample cohort

OBJECTIVE

To investigate the bidirectional association between migraine and rheumatoid arthritis (RA).

DESIGN

Two longitudinal follow-up studies.

SETTING

Data collected from a national cohort between 2002 and 2013 by the Korean National Health Insurance Service-Health Screening Cohort.

PARTICIPANTS

In cohort 1, matching resulted in the inclusion of 31 589 migraine patients and 126 356 control I participants. In cohort 2, matching resulted in the inclusion of 9287 RA patients and 37 148 control II participants.

PRIMARY AND SECONDARY OUTCOME MEASURES

The HRs for RA in patients with migraine (cohort 1) and migraine in patients with RA (cohort 2) were analysed using stratified Cox proportional hazard models after adjusting for autoimmune disease, Charlson Comorbidity Index scores without rheumatoid diseases, obesity (body mass index), smoking and history of alcohol intake. Subgroup analyses stratified by age, sex, income and region of residence were also performed.

RESULTS

The incidence of RA in the migraine group (2.0% (640/31 589)) was higher than that in the control I group (1.4% (1709/126 356), p<0.001). The adjusted HR for RA in the migraine without aura group was 1.48 (95% CIs=1.34 to 1.63, p<0.001).The incidence of migraine in the RA group (6.4% (590/9287)) was higher than that in the control II group (4.6% (1721/37 148), p<0.001). The adjusted HR for migraine without aura in the RA group was 1.35 (95% CI=1.23 to 1.49, p<0.001).

CONCLUSION

Migraine increases the risk of RA, and RA is also associated with an increased risk of migraine.

Prevalence of chronic obstructive pulmonary disease in patients with rheumatoid arthritis: A cross-sectional study

OBJECTIVE

Rheumatoid arthritis (RA) and chronic obstructive pulmonary disease (COPD) are both chronic inflammatory diseases; the prevalence of COPD in RA patients is known to be high. However, the prevalence of both RA and COPD differs according to sex; the relationship between RA and COPD may also vary according to sex. Therefore, we investigated the prevalence of COPD and its association in patients with RA in Korea by sex.

METHODS

We conducted a nationwide cross-sectional study using data from the Korea National Health and Nutrition Examination Survey. A total of 12 417 men and 15 878 women were included. In this study, RA was defined as physician diagnosed or currently under RA treatment. COPD was defined based on spirometry results, chronic symptoms, and smoking history. Multivariable logistic regression models were employed and we calculated the odds ratios (ORs) and 95% confidence intervals (CIs) for COPD prevalence in patients with RA.

RESULTS

The prevalence of COPD was 15.5% in men with RA, 3.5% in women with RA, 7.8% in men without RA, and 2.2% in women without RA. After adjustment for potential confounding variables, including smoking status, RA was significantly associated with COPD in men (OR 2.16, 95% CI 1.06-4.40), but not in women (OR 1.58, 95% CI 0.81-3.10).

CONCLUSIONS

In Korea, the prevalence of COPD was high in patients with RA of both sexes; RA and COPD was significantly likely to be associated in men, but not in women.

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.

Psoriasis is associated with an increased risk of osteoporosis: follow-up and nested case-control studies using a national sample cohort

A total of 25,306 psoriasis participants were matched to 101,224 controls, and the occurrence of osteoporosis was analyzed. Additionally, 79,212 osteoporosis patients were matched to 79,212 controls and a previous history of psoriasis was analyzed. Psoriasis increased the risk of osteoporosis among participants aged ≥ 40 years.

INTRODUCTION

The aim of the present study was to evaluate the association between psoriasis and osteoporosis using two different studies.

METHODS

Data from the Korean National Health Insurance Service-Health Screening Cohort of participants aged ≥ 40 years were collected from 2002 to 2013. Psoriasis and osteoporosis were included using International Classification of Diseases (ICD)-10 codes. In study I (a follow-up study), a total of 25,306 psoriasis participants were matched to 101,224 controls with respect to age, sex, income, and region of residence, and the occurrence of osteoporosis was analyzed. Crude (simple) and adjusted hazard ratios (HRs) were analyzed using a stratified Cox proportional hazard model. In study II (a nested case-control study), a total of 79,212 osteoporosis patients were matched to 79,212 controls and a previous history of psoriasis was analyzed. Crude and adjusted odds ratios (ORs) were analyzed using a conditional logistic regression analysis. Subgroup analyses were conducted according to age group and sex.

RESULTS

The adjusted HR of osteoporosis was 1.09 (95% confidence interval [CI] = 1.05-1.13, P < 0.001) in study I. In the subgroup analysis according to age and sex, the results were consistent except for ≥ 60-year-old women. The adjusted OR of psoriasis was 1.21 (95% CI = 1.16-1.27, P < 0.001) in study II. All subgroups demonstrated high adjusted ORs of osteoporosis for psoriasis.

CONCLUSIONS

Psoriasis increased the risk of osteoporosis among participants aged ≥ 40 years in Korea.

Incidence and risk of developing rheumatic diseases in 19,724 patients with palindromic rheumatism in South Korea: A nationwide population-based study

OBJECTIVES

The spectrum of progression of palindromic rheumatism (PR) to chronic diseases is quite variable. Hence, this study aimed to investigate the incidence and risk of developing rheumatic diseases in PR using nationwide, population-based medical claims data from Korea.

METHODS

We assessed the incidence rate (IR) of PR in the population in the given year. After matching individuals with PR with those without PR (1:10) for age, gender, and the index year, we calculated the hazard ratios (HRs) with 95% confidence intervals (CIs) using the Cox proportional hazard model.

RESULTS

A total of 19,724 newly diagnosed incident PR cases were identified from 2010 to 2016. The mean age was 50.2±14.9 years. The incidence of PR was 7.02 (95% CI 6.92-7.12) per 100,000 person-years (6.22 and 7.80 in men and women, respectively). During observation, 8.79% patients with PR and 0.30% individuals without PR developed various outcome diseases. Patients with PR had an increased risk of seropositive rheumatoid arthritis (HR 46.51, 95% CI [41.05-52.69]), psoriatic arthritis (44.79 [15.16-132.35]), systemic lupus erythematosus (24.53 [16.15-37.24]), mixed connective tissue disease (22.01 [7.65-63.34]), Behçet's disease (21.04 [13.81-32.06]), Sjögren's syndrome (12.36 [8.54-17.88]), ankylosing spondylitis (9.00 [6.67-12.15]), dermatomyositis/polymyositis (6.14 [2.55-14.82]), and systemic sclerosis (3.75 [1.47-9.58]) compared with individuals without PR.

CONCLUSIONS

This nationwide, population-based cohort study demonstrated that about one-eleventh of patients with PR eventually develop systemic rheumatic diseases and that patients with PR have an increased risk of developing various rheumatic diseases including seropositive rheumatoid arthritis.

Risk of autoimmune diseases in recurrent aphthous ulcer patients: A nationwide population study

OBJECTIVE

To estimate the risk of developing autoimmune disease in patients diagnosed having recurrent aphthous stomatitis (RAS) through a nationwide population-based cohort study.

METHODS

This study included two group of patients who had three or more episodes with aphthae diagnosed from their physician (RAS group) and a similar matched group of patients without aphthae (control group). Both groups were collected within the period of 2005-2007 from the Korean National Health Insurances claims database. Non-RAS cohort was matched after frequency matching. The final enrolled subjects were observed during a follow-up period from 2008 to 2015 and those who received autoimmune diseases diagnoses during follow-up were identified. The hazard ratio (HR) for developing autoimmune diseases was estimated.

RESULTS

A total of 4,637 patients with RAS and 4,637 controls were included. The risk of overall autoimmune diseases was significantly increased in the RAS group (adjusted HR [aHR)], 1.19). With regard to each disease entity, patients with RAS showed an increased risk of Behcet's disease (31.16), systemic lupus erythematous (SLE) (1.74), ankylosing spondylitis (AS) (1.47), gout (1.47), Hashimoto thyroiditis (1.42), Graves' disease (1.37), and rheumatoid arthritis (RA) (1.19).

CONCLUSION

RAS-like lesion may be an early sign of systemic autoimmune disease, as it was associated with an increased risk of Graves' disease, Hashimoto thyroiditis, SLE, AS, gout, RA, and Behcet's disease from real-world data.

The global prevalence of rheumatoid arthritis: a meta-analysis based on a systematic review

The objective is to determine the global population prevalence of rheumatoid arthritis (RA) based on population-based studies and assess factors that influence RA prevalence estimates. Four electronic databases were searched (ProQuest Central, MEDLINE, Web of Science, and EMBASE) for peer-reviewed English publications that report prevalence estimates of RA from 1980 and 2019. We included case-control studies, cross-sectional studies, and prospective or retrospective cohort studies in our search strategy. A random-effect meta-analysis model was used to produce the pooled prevalence estimates. The potential between-study heterogeneity was identified using sensitivity analysis, sub-group and meta-regression analyses. A total of 67 studies were included in the meta-analysis, containing 742,246 RA patients and 211,592,925 healthy controls in the study period. The global RA prevalence estimate was 0.46% (95% confidence interval [CI] 0.39-0.54; I² = 99.9%) with a 95% prediction interval (0.06-1.27). The RA point-prevalence was 0.45% (95% CI 0.38-0.53%) between 1986 and 2014, while the pooled period-prevalence was 0.46% (95% CI 0.36% and 0.57%) from 1955 to 2015. The highest RA pooled prevalence (0.69%; 95% CI 0.47-0.95) was derived from linked data source studies. Based on meta-regression, the factors that explain the studies' heterogeneity of RA prevalence, including geographical location, the risk bias assessment of studies and sample size. The global prevalence of RA between 1980 and 2019 was 460 per 100,000 population, with variations due to geographical location and study methodology. Linked data are the preferred method to estimate RA population prevalence as they provide the best case ascertainment.

Increased Risk of Temporomandibular Joint Disorder in Patients with Rheumatoid Arthritis: A Longitudinal Follow-Up Study

We evaluated the incidence of temporomandibular disorder (TMD) in patients with rheumatoid arthritis (RA) and examined the association between TMD and RA, through longitudinal follow-up. Population data from the Korean National Health Insurance Service-Health Screening Cohort from 2002 to 2015 was used. From 514,866 subjects, 3122 with RA were matched with 12,488 controls in a 1:4 ratio. The crude and adjusted models (for obesity, smoking, alcohol consumption, blood pressure, blood glucose, total cholesterol, and Charlson Comorbidity Index scores) were calculated. Chi-square tests, Kaplan-Meier (KM) analysis, and two-tailed analyses were used for statistical analysis. Stratified Cox proportional hazard models were used to assess the hazard ratios (HR) and 95% confidence intervals (CI) for TMD in the RA group, compared to those in the control group. The adjusted HR for TMD in RA was 2.52 (95% CI = 1.70–3.74), compared to the control group. The results were consistent with the subgroup analyses, according to age and sex, except in men older than 60 years of age. KM analysis showed similar results. Hence, we found that patients with RA have a higher risk of TMD, and should be observed for symptoms of the initial stage of TMD to prevent the risk of aggravation.

Bidirectional association between GERD and rheumatoid arthritis: two longitudinal follow-up studies using a national sample cohort

Several previous studies have suggested a relationship between GERD and RA. However, no study has investigated the bidirectional relationship between GERD and RA. This study aimed to evaluate the causal relationships between rheumatoid arthritis (RA) and gastroesophageal reflux disease (GERD). Participants aged ≥ 20 years old in the Korean Health Insurance Review and Assessment Service-National Sample Cohort from 2002 to 2013 were enrolled. In study I, 132,140 GERD participants were 1:2 matched with 264,280 control I participants. In study II, 6615 RA participants were 1:4 matched with 26,460 control II participants. Both control I and control II groups were matched with their study groups for age, sex, income, and region of residence. The occurrence of RA (study I) and GERD (study II) were followed up in both the study and control groups. The hazard ratios (HRs) of GERD for RA (study I) and of RA for GERD (study II) were analysed using stratified Cox-proportional hazards models. In study I, 0.8% (1,034/132,140) of the GERD group and 0.5% (1,290/264,280) of the control I group had RA (P < 0.001). The GERD group demonstrated a 1.49-fold higher adjusted HR than did the control I group (95% confidence interval (95% CI) = 1.37-1.62, P < 0.001). In study II, 22.5% (1,490/6,615) of the RA group and 15.2% (4,034/26,460) of the control II group had GERD (P < 0.001). The RA group showed a 1.46-fold higher adjusted HR than did the control II group (95% CI = 1.38-1.55, P < 0.001). GERD and RA have bidirectional associations in Korean adult population. Key Points • Several previous studies have suggested a relationship between gastroesophageal reflux disease (GERD) and rheumatoid arthritis (RA). • However, no study has investigated the bidirectional relationship between GERD and RA. • This is the first study to present a bidirectional relationship between GERD and RA. • GERD and RA have bidirectional relations with each other.

The association between Bell's palsy and rheumatoid arthritis: A longitudinal study

This study aimed to evaluate the relationship between Bell's palsy and rheumatoid arthritis in a national sample cohort from Korea.Data were collected for individuals ≥20 years old from 2002 to 2013 in the Korean National Health Insurance Service-National Sample Cohort. We extracted data for patients with rheumatoid arthritis (n = 7628) and 1:4-matched controls (n = 30,512) and analyzed the occurrence of Bell's palsy in both groups. Matching was performed based on age, sex, income, and region of residence. Rheumatoid arthritis was diagnosed according to International Classification of Disease-10 (ICD-10) codes (M05-M06) and the prescription of biological agents and/or disease-modifying antirheumatic drugs. Bell's palsy patients were diagnosed according to ICD-10 code H912 and treatment ≥2 times with steroids. Adjusted hazard ratios (HRs) were calculated using stratified Cox proportional hazard models for the Charlson comorbidity index and 95% confidence intervals (CIs). Subgroup analyses based on age and sex were also performed.The rates of Bell's palsy were similar between the rheumatoid arthritis group (0.5% [38/7628]) and the control group, with no significant difference (0.4% [124/30,512], P = .270). The adjusted HR for Bell's palsy was 1.12 (95% CI, 0.78-1.62) in the rheumatoid arthritis group (P = .540). In the subgroup analyses according to age and sex, the relationship between Bell's palsy and rheumatoid arthritis did not reach statistical significance.The risk of Bell's palsy was not increased in patients with rheumatoid arthritis.

Acetabular cup migration after primary cementless total hip arthroplasty in rheumatoid arthritis and its influencing factors: a comparative study with osteoarthritic hip

PURPOSE

To compare the radiographic migration profiles of primary cementless total hip arthroplasty (THA) between patients with rheumatoid arthritis (RA) and those with osteoarthritis (OA).

METHODS

A total of 197 patients (215 hips) who underwent cementless THA for RA or OA between January 2001 and January 2013 and followed up for a minimum of 5.5 years were included. Ninety-four RA patients (109 hips) were compared with 103 OA patients (106 hips). Radiological evaluation was performed for acetabular cup loosening, and cup migration was measured using Einzel-Bild-Röntgen-Analyse (EBRA) software. Multiple variables were assessed to identify influencing factors for cup migration.

RESULTS

Early cup migration was observed in 13 hips (11.9%) in the RA group and four hips (3.8%) in the OA group, showing a significant difference (p = 0.041). Acetabular cup loosening occurred in three cups (2.8%) in the RA group and in one cup (0.9%) in the OA group, showing no significant difference (p = 0.321). Total cup migration was higher in the RA group (2.62 mm) than in the OA group (1.44 mm, p = 0.005). Total cup migration was significantly higher in patients aged < 50 years than in those aged > 50 years (p = 0.005). Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody influenced total cup migration. Patients with seropositive RA showed significantly higher total cup migration and early cup migration incidence than those with seronegative RA (p = 0.005, p = 0.038, respectively).

CONCLUSIONS

Acetabular cups in primary cementless THAs of RA patients were less stable in terms of cup migration compared with that of OA patients.

Physical and Psychological Factors Affecting Falls in Older Patients with Arthritis

As the population ages, falls are becoming one of the leading causes of morbidity and mortality. Joint disease (either osteoarthritis or rheumatoid arthritis) is a well-known predictor of falls, and these medical conditions increase in accordance with the aging population. This study aimed to describe individual, physical, and psychological characteristics between older adults with and without a fall history. Further, we aimed to identify statistically significant physical or psychological factors associated with falls by controlling individual variables. We analyzed data from the 2014 Survey of Living Conditions and Welfare Needs of Korean Older Adults. Adults aged 65 years or over with doctor-diagnosed joint disease were eligible. A total of 2707 women and 784 men (n = 3491) were enrolled. Of these, 1174 patients suffered a fall within a year (average number of falls = 2.4). We adopted individual variable-adjusted models and found that limited activities of daily living (odds ratio (OR) 1.4, 95% confidence interval (CI) 1.04-1.87), fear of falling (OR 7.18, 95% CI 4.26-12.09), and depression (OR 1.28, 95% CI 1.09-1.50) significantly increased fall risks on logistic regression analysis. Our findings suggest that physical and psychological factors, especially the fear of falling, need to be addressed to prevent falls in elderly patients with arthritis.

Simplified disease activity changes in real-world practice: a nationwide observational study of seropositive rheumatoid arthritis patients with moderate-to-high disease activity

BACKGROUND/AIMS

The objective of this study was to compare changes in the simplified disease activity index (SDAI) between biologic (b) and conventional (c) disease-modifying antirheumatic drugs (DMARD) users with seropositive rheumatoid arthritis (RA) in daily clinical practice.

METHODS

This was a nationwide multicenter observational study. Patients who had three or more active joint counts and abnormal inf lammatory marker in blood test were enrolled. The selection of DMARDs was determined by the attending rheumatologist. Clinical parameters, laboratory findings, and Health Assessment Questionnaire (HAQ) scores were obtained at baseline and at 6 and 12 months. Serial SDAI changes and clinical remission rate at 6 and 12 months were assessed.

RESULTS

A total of 850 patients participated in this study. The mean baseline SDAI score in bDMARD group was higher than that in cDMARD group (32.08 ± 12.98 vs 25.69 ± 10.97, p < 0.0001). Mean change of SDAI at 12 months was -19.0 in the bDMARD group and -12.6 in the cDMARD group (p < 0.0001). Clinical remission rates at 12 months in bDMARD and cDMARD groups were 15.4% and 14.6%, respectively. Patient global assessment and HAQ at 12 months were also significantly improved in both groups. Multivariate logistic regression showed that baseline HAQ score was the most notable factor associated with remission.

CONCLUSION

There was a significant reduction in SDAI within 12 months after receiving DMARDs in Korean seropositive RA patients irrespective of bDMARD or cDMARD use in real-world practice. Clinical remission was achieved in those with lower baseline HAQ scores.

Association between depression and rheumatoid arthritis: two longitudinal follow-up studies using a national sample cohort

Objective

To investigate the bidirectional relation between RA and depression.

Methods

Data from the Korean Health Insurance Review and Assessment Service – National Sample Cohort from 2002 to 2013 were analysed. Patients ≥20 years of age were included. Study I was conducted with 38 087 depression patients and 152 348 matched control participants. Study II was conducted with 7385 RA patients and 29 540 matched control participants. Stratified Cox proportional hazards models were used to analyse the hazard ratios (HRs) for depression and RA (study I) and for RA and depression (study II). The data were adjusted by the Charlson comorbidity index; rheumatic disease was excluded. Subgroups were also analysed according to age and sex.

Results

A total of 0.7% (1260/38 087) of the depression group and 0.6% (883/152 348) of the control I group had RA (P = 0.02). The HR for RA in the depression group was not significantly higher than that in control I group. In study II, 5.5% (408/7385) of the RA group and 4.3% (1246/29 540) of the control II group presented with depression (P &lt; 0.001). The RA patients showed an adjusted depression HR that was 1.20 times higher (95% CI 1.07, 1.34; P = 0.002) than that of the control group. The &gt;30-years-old and women subgroups of RA patients showed higher depression HRs than the control subgroups.

Conclusion

RA increased the risk of depression; however, depression did not increase the risk of RA in the Korean adult population.

Appendectomy and rheumatoid arthritis: A longitudinal follow-up study using a national sample cohort

The present study evaluated the association between appendectomy and rheumatoid arthritis (RA) using a national sample cohort of the Korean population. In this cohort study, the Korean National Health Insurance Service-National Sample Cohort of individuals ≥20 years old was collected from 2002 to 2013. A total of 14,995 appendectomy participants were 1:4 matched with 59,980 control subjects for age, group, sex, income group, region of residence, hypertension, diabetes, and dyslipidemia. We analyzed the occurrence of RA in both the appendectomy and control groups. Appendectomies were identified using operation codes for appendicitis only. RA was defined by International Classification of Disease-10 codes (M05 or M06) and medication histories. Crude and adjusted hazard ratios (HRs) were analyzed using a stratified Cox proportional hazard model. Subgroup analyses were performed on groups stratified by age and sex. The adjusted HR for RA was 1.02 (95% confidence interval = 0.76-1.38) in the appendectomy group (P = .883). In all of the subgroup analyses according to age and sex, the adjusted HRs for RA were not higher in the appendectomy group than those in the control group. We could not identify any significant relationship between appendectomy and RA.

Rheumatoid arthritis and neurodegenerative dementia: a nested case-control study and a follow-up study using a national sample cohort

OBJECTIVES

The present study evaluated the associations between rheumatoid arthritis (RA) and neurodegenerative dementia using a Korean national sample cohort.

METHODS

We designed two studies using the Korean National Health Insurance Service-National Sample Cohort from 2002 to 2013. Study I included participants with dementia matched 1:4 with controls and analyzed the participants' history of RA. Study II included participants with RA matched 1:4 with controls and analyzed the occurrence of dementia. RA was defined by the presence of relevant ICD-10 codes (M05 or M06) and medication histories. Neurodegenerative dementia was defined using ICD-10 codes (G30 or F00). Crude and adjusted odds ratios (ORs) were analyzed using conditional logistic regression analyses. Crude and adjusted hazard ratios (HRs) were analyzed using the stratified Cox proportional hazard model. Subgroup analyses were performed on groups stratified by age and sex.

RESULTS

The adjusted ORs for RA were 0.96 (95% CI = 0.78-1.16, P = 0.644) in the dementia group in study I. The adjusted HRs for dementia were 0.91 (95% CI = 0.76-1.10, P = 0.319) in the RA group in study II. No subgroup analysis reached the statistical significance level.

CONCLUSION

We could not identify any significant relationship between RA and dementia.Key Points• Two studies were conducted to identify the relationship between rheumatoid arthritis and dementia using national cohort data.• Neither study showed any association between rheumatoid arthritis and dementia.

Respiratory viral infections and the risk of rheumatoid arthritis

Background

We aimed to investigate the effects of ambient respiratory viral infections in the general population on rheumatoid arthritis (RA) development.

Methods

Data of weekly incident RA (2012–2013) were obtained from the Korean National Health Insurance claims database, and those of weekly observations on eight respiratory viral infections were obtained from the Korea Centers for Disease Control and Prevention database. We estimated the percentage change in incident RA associated with ambient mean respiratory viral infections using a generalized linear model, after adjusting for time trend, air pollution, and meteorological data.

Results

A total of 24,117 cases of incident RA (mean age 54.7 years, 18,688 [77.5%] women) were analyzed. Ambient respiratory viral infections in the population were associated with a higher number of incident RA over time, and its effect peaked 6 or 7 weeks after exposure. Among the 8 viruses, parainfluenza virus (4.8% for 1% respiratory viral infection increase, 95% CI 1.6 to 8.1, P = .003), coronavirus (9.2%, 3.9 to 14.8, P < .001), and metapneumovirus (44%, 2.0 to 103.4, P = .038) were associated with increased number of incident RA. The impact of these respiratory viral infections remained significant in women (3.8%, 12.1%, and 67.4%, respectively, P < .05) and in older patients (10.7%, 14.6%, and 118.2%, respectively, P < .05).

Conclusions

Ambient respiratory viral infections in the population were associated with an increased number of incident RA, especially in women and older patients, suggesting that respiratory viral infections can be a novel environmental risk factor for the development of RA.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1977-9) contains supplementary material, which is available to authorized users.

Dipeptidyl peptidase-4 inhibitors lower the risk of autoimmune disease in patients with type 2 diabetes mellitus: A nationwide population-based cohort study

AIMS

To evaluate the real-world effect of dipeptidyl peptidase-4 inhibitor (DPP4i) on the incidence of autoimmune diseases (AD), including rheumatoid arthritis (RA), inflammatory bowel diseases, multiple sclerosis and systemic lupus erythematosus.

METHODS

We identified new users of DPP4i (n = 497 619) or non-DPP4i (n = 643 165) oral combination therapy between 1 January 2011 and 30 June 2015 among patients with type 2 diabetes mellitus in the Korean national health insurance claims database. Patients were followed from the date of initiation of combination therapy until AD outcome, censoring for treatment discontinuation or switching, death or end of study (31 August 2016). Adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for RA, inflammatory bowel diseases, other AD (multiple sclerosis and systemic lupus erythematosus), and the composite of all outcomes were estimated using propensity score (PS)-adjusted Cox model.

RESULTS

In the PS-weighted and PS-matched analysis, the risk of incident RA was decreased for DPP4i initiators compared with non-DPP4i initiators (aHR 0.67 [95% CI 0.49-0.92] and aHR 0.72 [95% CI 0.51-1.01], respectively). In both analyses, the risk of incident composite AD was also decreased for DPP4i initiators compared with non-DPP4i initiators (aHR 0.82 [95% CI 0.68-0.99] and aHR 0.76 [95% CI 0.62-0.93], respectively).

CONCLUSIONS

In this large population-based cohort study, upfront DPP4i combination therapy was associated with a lower risk of composite AD compared with initial non-DPP4i combination therapy.

Increased risk of asthma in patients with rheumatoid arthritis: A longitudinal follow-up study using a national sample cohort

The aim of this study was to evaluate the risk of asthma in rheumatoid arthritis patients using matched control group for socioeconomic factors and past medical history. Adults >20 years old were collected from the Korean Health Insurance Review and Assessment Service - National Sample Cohort (HIRA-NSC) from 2002 through 2013. A total of 6,695 individuals with rheumatoid arthritis were matched for age, sex, income, region of residence, hypertension, diabetes, and dyslipidemia with 26,780 individuals included in a control group. In both the rheumatoid arthritis and control groups, subjects' history of asthma was evaluated. Asthma (J45 and J46) and rheumatoid arthritis (M05 and M06) were included based on the International Classification of Disease-10 (ICD-10) codes and medication history. The crude and adjusted (depression and Charlson Comorbidity Index) hazard ratios (HRs) and 95% confidence intervals (CI) of asthma for rheumatoid arthritis patients were analyzed using a stratified Cox proportional hazard model. Subgroup analyses were conducted according to age and sex, number of treatment histories, and medication histories. Approximately 16.4% (1,095/6,695) of rheumatoid arthritis group and 13.0% (3,469/26,780) of the control group had asthma (P < 0.001). The rheumatoid arthritis group demonstrated a higher adjusted HR for asthma than the control group (adjusted HR = 1.23, 95% CI = 1.15-1.32, P < 0.001). This result was consistent in all subgroups. Rheumatoid arthritis was related to an increase risk of asthma.

Discrepancy between subjective and objective measures of cognitive impairment in patients with rheumatoid arthritis

This study explored the discrepancy between perceived cognitive dysfunction and computerized neuropsychological test performance in Korean patients with RA. Individuals with RA were recruited by their rheumatologists during follow-up visits at one hospital in Korea. After getting signed consents, a trained research nurse assessed participants with a range of physical, psychosocial, and biological metrics. Subjective cognitive dysfunction was assessed using the Perceived Deficits Questionnaire (PDQ; range 0-20). Objective cognitive impairment was assessed using a set of 6 computerized neurocognitive tests yielding 12 indices covering a range of cognitive domains. Subjects were classified as 'impaired' if they performed 1 SD below age-based population norms on each test. A total cognitive function score was calculated by summing the transformed scores (range 0-12). Multiple linear regression analyses determined the relationship of total cognitive function score with PDQ score, controlling for disease activity, functional limitations, and psychological factors. Forty subjects (mean ± SD age: 63.1 ± 11.4 years) were included. Mean ± SD scores of total cognitive function and PDQ were 7.3 ± 2.7 (2-12) and 11.8 ± 5.1 (5-25), respectively. In multivariate analysis, there was no significant relationship between total cognitive function score and PDQ score. However, depression and sleep quality (β = 0.37, p = 0.025; β = 0.17, p = 0.034) were significantly associated with PDQ score. The findings emphasize the gap between subjective and objective measures of cognitive impairment and the importance of considering psychological factors within the context of cognitive complaints in clinical settings.

Brief Report: Utilization of the First Biosimilar Infliximab Since Its Approval in South Korea

OBJECTIVE

The US Food and Drug Administration is considering an application for a biosimilar version of infliximab, which has been available in South Korea since November 2012. The aim of the present study was to examine the utilization patterns of both branded and biosimilar infliximab and other tumor necrosis factor (TNF) inhibitors in South Korea before and after the introduction of this biosimilar infliximab.

METHODS

Using claims data from April 2009 to March 2014 from the Korean Health Insurance Review and Assessment Service database, which includes the entire South Korean population, the number of claims for biosimilar infliximab was assessed. A segmented linear regression model was used to examine the utilization patterns of infliximab (the branded and biosimilar versions) and other TNF inhibitors (adalimumab and etanercept) before and after the introduction of the biosimilar infliximab.

RESULTS

In total, 20,976 TNF inhibitor users were identified from the South Korean claims database, including 983 with a prescription claim for biosimilar infliximab. Among all of the claims for any version of infliximab, the proportion of biosimilar infliximab claims increased to 19% through March 2014. Before November 2012, each month there were 33 (95% confidence interval [95% CI] 32, 35) more infliximab claims, 44 (95% CI 40, 48) more etanercept claims, and 50 (95% CI 47, 53) more adalimumab claims. After November 2012, there were significant changes in the slopes for trend in usage, with additional increases in the use of branded and biosimilar infliximab (9 more claims per month, 95% CI 2, 17) and decreases in the use of etanercept (-52 claims per month, 95% CI -66, -38) and adalimumab (-21 claims per month, 95% CI -35, -6).

CONCLUSION

During the first 15 months since its introduction in South Korea, one-fifth of all infliximab claims were for the biosimilar version. Introduction of biosimilar infliximab may affect the use of other TNF inhibitors, and the magnitude of change in usage will likely differ in other countries.

Treatment of connective tissue disease-associated interstitial lung disease: the pulmonologist's point of view

Interstitial lung disease (ILD) occurs in 15% of patients with collagen vascular disease (CVD), referred to as connective tissue disease (CTD). Despite advances in management strategies, ILD continues to be a significant cause of mortality in patients with CVD-associated ILD (CTD-ILD). There is a lack of randomized, clinical trials assessing pharmacological agents for CTD-ILD, except in cases of ILD-associated systemic sclerosis (SSc). This may be due to the lack of CTD cases available, the difficulty of histological confirmation of ILD, and the various types of CTD and ILD. As a result, evidence-based pharmacological treatment of CTD-ILD is not yet well established. CTD-ILD presents with varying degrees of histology, from inflammation to fibrosis, and a wide spectrum of clinical manifestations, from minimal symptoms to respiratory failure. This renders it difficult for clinicians to make decisions regarding treatment options, observational strategies, optimal timing for interventions, and the appropriateness of pharmacological agents for treatment. There is no specific treatment for reversing fibrosis-like idiopathic pulmonary fibrosis in a clinical setting. This review describes pharmacological interventions for SSc-ILD described in randomized control trials, and presents an overview of recent advances of CTD-ILD-dependent treatments based on the types of CTD.

Influence of Cigarette Smoking on Rheumatoid Arthritis Risk in the Han Chinese Population

OBJECTIVES

Cigarette smoking has been shown in European populations to be associated with rheumatoid arthritis (RA) susceptibility. This study aims to examine the association of smoking with RA in the Han Chinese population.

METHODS

718 Han Chinese RA patients and 404 healthy controls were studied. The associations of cigarette smoking (current, former or ever vs. never smokers, and pack-years of exposure) with RA, anti-cyclic citrullinated peptide antibody (ACPA) positive RA, IgM rheumatoid factor (RF) positive RA, and baseline radiographic erosions (modified van der Heijde-Sharp scores) were assessed. The interaction between smoking and the HLA-DRB1 shared epitope (SE) in RA was also examined.

RESULTS

In this study, 11 (1.53%) cases and 6 (1.49%) controls were former smokers (p = 0.95), while 95 (13.23%) cases and 48 (11.88%) controls were current smokers (p = 0.52). Trends toward associations between smoking status (ever vs. never) with RA-overall (p = 0.15, OR = 1.44), ACPA-positive RA (p = 0.24, OR = 1.37), RF-positive RA (p = 0.14, OR = 1.46), or the presence of radiographic erosions (p = 0.66, OR = 1.28) were observed although individually here were not statistically significant. There was no evidence of statistical interaction between smoking status (ever vs. never) and SE for all RA, ACPA-positive RA, ACPA-negative RA, RF-positive RA, RF-negative RA (p = 0.37, 0.50, 0.24, 0.26, and 0.81 respectively), and the 95% CI for the attributable proportion for all interactions included 0.

CONCLUSION

This is the first study to examine the association of cigarette smoking with RA in the Han Chinese population. This study shows a trend toward an interaction between smoking and SE carriage influencing the risk of RA, though findings were not statistically significant. It is possible that in the presence of universal exposure to heavy air pollution the effect of smoking on RA risk may be obscured.

Asthma and the Risk of Rheumatoid Arthritis: An Insight into the Heterogeneity and Phenotypes of Asthma

Asthma is traditionally regarded as a chronic airway disease, and recent literature proves its heterogeneity, based on distinctive clusters or phenotypes of asthma. In defining such asthma clusters, the nature of comorbidity among patients with asthma is poorly understood, by assuming no causal relationship between asthma and other comorbid conditions, including both communicable and noncommunicable diseases. However, emerging evidence suggests that the status of asthma significantly affects the increased susceptibility of the patient to both communicable and noncommunicable diseases. Specifically, the impact of asthma on susceptibility to noncommunicable diseases such as chronic systemic inflammatory diseases (e.g., rheumatoid arthritis), may provide an important insight into asthma as a disease with systemic inflammatory features, a conceptual understanding between asthma and asthma-related comorbidity, and the potential implications on the therapeutic and preventive interventions for patients with asthma. This review discusses the currently under-recognized clinical and immunological phenotypes of asthma; specifically, a higher risk of developing a systemic inflammatory disease such as rheumatoid arthritis and their implications, on the conceptual understanding and management of asthma. Our discussion is divided into three parts: literature summary on the relationship between asthma and the risk of rheumatoid arthritis; potential mechanisms underlying the association; and implications on asthma management and research.

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.

A population-based study on the association between rheumatoid arthritis and voice problems

The objective of this study was to investigate whether rheumatoid arthritis increases the frequency of organic laryngeal lesions and the subjective voice complaint rate in those with no organic laryngeal lesion. We performed a cross-sectional study using the data from 19,368 participants (418 rheumatoid arthritis patients and 18,950 controls) of the 2008-2011 Korea National Health and Nutrition Examination Survey. The associations between rheumatoid arthritis and organic laryngeal lesions/subjective voice complaints were analyzed using simple/multiple logistic regression analysis with complex sample adjusting for confounding factors, including age, sex, smoking status, stress level, and body mass index, which could provoke voice problems. Vocal nodules, vocal polyp, and vocal palsy were not associated with rheumatoid arthritis in a multiple regression analysis, and only laryngitis showed a positive association (adjusted odds ratio, 1.59; 95 % confidence interval, 1.01-2.52; P = 0.047). Rheumatoid arthritis was associated with subjective voice discomfort in a simple regression analysis, but not in a multiple regression analysis. Participants with rheumatoid arthritis were older, more often female, and had higher stress levels than those without rheumatoid arthritis. These factors were associated with subjective voice complaints in both simple and multiple regression analyses. Rheumatoid arthritis was not associated with organic laryngeal diseases except laryngitis. Rheumatoid arthritis did not increase the odds ratio for subjective voice complaints. Voice problems in participants with rheumatoid arthritis originated from the characteristics of the rheumatoid arthritis group (higher mean age, female sex, and stress level) rather than rheumatoid arthritis itself.

Promoter polymorphism (-590, T/C) of interleukin 4 (IL4) gene is associated with rheumatoid arthritis: An updated meta-analysis

Rheumatoid arthritis (RA) is a chronic disease. It causes chronic inflammation of the joint. Recent studies suggested that interleukin 4 (IL4) contributes to susceptibility and severity of rheumatoid arthritis (RA). Especially, it was reported that promoter polymorphism (-590, T/C) of IL4 gene has been associated with susceptibility of RA. The aim of present study was to investigate whether the promoter polymorphism (-590, T/C) of IL4 gene is associated with the susceptibility of RA using meta-analysis. And in order to perform meta-analysis, comprehensive meta analysis program was used. Genetic models (co-dominant, dominant, recessive, and allele) were used to determine odds ratios (ORs), 95% confidence intervals (CIs), and P values. Nine case-control studies with case and control design were included in this meta-analysis. Overall, meta-analysis revealed a strong association with susceptibility of RA [OR = 1.303, 95% CI = 1.093-1.554, P = 0.003 in allele model (C vs. T); OR = 1.247, 95% CI = 1.054-1.474, P = 0.010 in dominant model (CC vs. CT + TT); OR = 2.148, 95% CI = 1.263-3.651, P = 0.005 in recessive model (CC + CT vs. TT)]. Our data demonstrated that promoter polymorphism (-590, T/C) of IL4 gene may be contributed to susceptibility of RA. However, more studies with a larger sample size are needed to provide more precise evidence.

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.

Human autoimmune diseases: a comprehensive update

There have been significant advances in our understanding of human autoimmunity that have led to improvements in classification and diagnosis and, most importantly, research advances in new therapies. The importance of autoimmunity and the mechanisms that lead to clinical disease were first recognized about 50 years ago following the pioneering studies of Macfarlane Burnett and his Nobel Prize-winning hypothesis of the 'forbidden clone'. Such pioneering efforts led to a better understanding not only of autoimmunity, but also of lymphoid cell development, thymic education, apoptosis and deletion of autoreactive cells. Contemporary theories suggest that the development of an autoimmune disease requires a genetic predisposition and environmental factors that trigger the immune pathways that lead, ultimately, to tissue destruction. Despite extensive research, there are no genetic tools that can be used clinically to predict the risk of autoimmune disease. Indeed, the concordance of autoimmune disease in identical twins is 12-67%, highlighting not only a role for environmental factors, but also the potential importance of stochastic or epigenetic phenomena. On the other hand, the identification of cytokines and chemokines, and their cognate receptors, has led to novel therapies that block pathological inflammatory responses within the target organ and have greatly improved the therapeutic effect in patients with autoimmune disease, particularly rheumatoid arthritis. Further advances involving the use of multiplex platforms for diagnosis and identification of new therapeutic agents should lead to major breakthroughs within the next decade.