Background/Aims: We aimed to compare the effectiveness and safety of Janus kinase inhibitors (JAKi) vs. biologic disease- modifying antirheumatic drugs (bDMARD) in Korean patients with rheumatoid arthritis (RA) who had an inadequate response to conventional synthetic DMARDs. Methods: A quasi-experimental, multi-center, prospective, non-randomized study was conducted to compare response rates between JAKi and bDMARDs in patients with RA naïve to targeted therapy. An interim analysis was performed to estimate the proportion of patients achieving low disease activity (LDA) based on disease activity score (DAS)–28– erythroid sedimentation rate (ESR) (DAS28-ESR) at 24 weeks after treatment initiation and to evaluate the development of adverse events (AEs). Results: Among 506 patients enrolled from 17 institutions between April 2020 and August 2022, 346 (196 JAKi group and 150 bDMARD group) were included in the analysis. After 24 weeks of treatment, 49.0% of JAKi users and 48.7% of bDMARD users achieved LDA (p = 0.954). DAS28-ESR remission rates were also comparable between JAKi and bDMARD users (30.1% and 31.3%, respectively; p = 0.806). The frequency of AEs reported in the JAKi group was numerically higher than that in the bDMARDs group, but the frequencies of serious and severe AEs were comparable between the groups. Conclusions Our interim findings reveal JAKi have comparable effectiveness and safety to bDMARDs at 24 weeks after treatment initiation.

Background: To investigate the use of cyclooxygenase-2 (COX-2) inhibitors as an initial drug treatment for knee osteoarthritis (OA) patients. Methods: From 2013 to 2015, patients with knee OA were identified from the Korean nationwide claims database. Among them, we extracted incident cases of knee OA to identify the initial drug treatment. Trends in the use of non-steroid anti-inflammatory drugs (NSAIDs) including COX-2 inhibitors were analyzed during the first year after their diagnosis. Associated factors for COX-2 inhibitor use were examined using a multivariate logistic regression model. Results: We identified 2,857,999 incident knee OA patients (955,259 in 2013, 981,314 in 2014, and 921,426 in 2015). The mean ± standard deviation age of patients was 64.2 ± 9.8 years. The frequency of COX-2 inhibitor use as initial treatment increased from 3.5% in 2013 to 7.2% in 2015 (P < 0.01). In patients taking the medication regularly for one year after diagnosis (medication possession ratio ≥ 50%), COX-2 inhibitor use also rapidly increased from 5.5% in 2013 to 11.1% in 2015 (P < 0.01). However, the frequencies of non-selective NSAID and analgesic use did not decrease remarkably. Factors associated with patients using COX-2 inhibitors on initial drug treatment were older age (odds ratio [OR], 1.08), female (OR, 1.24), and comorbidity (OR, 1.03). Type of institution, physician speciality, and insurance type of patients were also associated. Conclusion In Korea, COX-2 inhibitors have rapidly increased as an initial treatment for knee OA patients, but it has not appeared to reduce the use of non-selective NSAIDs and analgesics.

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.

Background/Aims: This study was performed to undertake cross-cultural adaptation and validation of the Educational Needs Assessment Tool (ENAT) in rheumatoid arthritis (RA) for use in Korea. Methods: The study involved two main phases: cross-cultural adaptation of the ENAT from English into Korean, and validation of the Korean ENAT. The first phase followed the established process of cross-cultural adaptation of self-report measures, and in the second phase, the Korean ENAT data were analyzed using the Rasch measurement model. Fit to the model was determined using the observed data infit and outfit statistics. Additional tests of validity included unidimensionality and internal consistency. Results: Adequate conceptual equivalence was achieved following the adaptation process. A total of 123 patients completed the Korean ENAT. The mean age was 46.7 ± 12.3 years and the majority of patients (81.3%) were female. Thirty-five of the 39 items gave good fit to the model. The four items deviating from the model had infit and outfit > 1.50. The item separation index (5.26) and item reliability index (0.97) provided evidence for good reliability of items. All seven domains of the Korean ENAT fit the Rasch model. The internal consistency of the Korean ENAT was high, and unidimensionality was confirmed (person separation index, 3.41; reliability index, 0.92; item separation index, 16.82; reliability index, 1.00). Conclusions Using the standard procedure for cross-cultural adaptation, the ENAT has been adapted into Korean, and Rasch analysis has confirmed the construct validity, reliability, and unidimensionality of the Korean ENAT.

Background/Aims: This study was performed to undertake cross-cultural adaptation and validation of the Educational Needs Assessment Tool (ENAT) in rheumatoid arthritis (RA) for use in Korea. Methods: The study involved two main phases: cross-cultural adaptation of the ENAT from English into Korean, and validation of the Korean ENAT. The first phase followed the established process of cross-cultural adaptation of self-report measures, and in the second phase, the Korean ENAT data were analyzed using the Rasch measurement model. Fit to the model was determined using the observed data infit and outfit statistics. Additional tests of validity included unidimensionality and internal consistency. Results: Adequate conceptual equivalence was achieved following the adaptation process. A total of 123 patients completed the Korean ENAT. The mean age was 46.7 ± 12.3 years and the majority of patients (81.3%) were female. Thirty-five of the 39 items gave good fit to the model. The four items deviating from the model had infit and outfit > 1.50. The item separation index (5.26) and item reliability index (0.97) provided evidence for good reliability of items. All seven domains of the Korean ENAT fit the Rasch model. The internal consistency of the Korean ENAT was high, and unidimensionality was confirmed (person separation index, 3.41; reliability index, 0.92; item separation index, 16.82; reliability index, 1.00). Conclusions Using the standard procedure for cross-cultural adaptation, the ENAT has been adapted into Korean, and Rasch analysis has confirmed the construct validity, reliability, and unidimensionality of the Korean ENAT.

Background: Patients with rheumatoid arthritis (RA) undergoing targeted therapy have a higher risk of developing tuberculosis (TB). This requires diagnosis and treatment of latent tuberculosis infection (LTBI). We aimed to evaluate whether diagnosis and treatment of LTBI in RA are effective in Korea, and to estimate the risk of TB development by calculating the incidence rate of active TB among RA patients receiving targeted therapy. Methods: We analyzed data from two prospective cohort studies of RA patients who received biologic disease-modifying antirheumatic drugs (bDMARDs) or Janus kinase (JAK) inhibitor.We selected new starters of targeted therapy and classified them into three groups receiving tumor necrosis factor (TNF) inhibitor, non-TNF inhibitor, and JAK inhibitor, respectively. We then compared LTBI prevalence, treatments, and active TB incidence during first-line therapy in each group. Results: A total of 765 RA patients (574 TNF inhibitor users, 132 non-TNF inhibitor users, and 59 JAK inhibitor users) were included in this study. Observation periods were 1,255.2 personyears (PYs), 264.7 PYs, and 53.3 PYs, respectively. All 765 patients underwent LTBI screening, and the positivity rate was 26.5% (n = 203). Of the 203 LTBI-positive patients, 189 (93.1%) received treatment. Only one patient, who was in the TNF inhibitor group, and was negative for the interferon gamma release assay (IGRA), did not receive LTBI treatment and developed active TB during follow-up. Conclusion Although the prevalence of LTBI in RA patients who started targeted therapy was slightly elevated, the Korean guidelines specifying LTBI screening and treatment were effective in preventing latent TB from becoming active.

Background: We aimed to examine the uptake of infliximab and etanercept biosimilars in patients with rheumatoid arthritis (RA) and its economic implication for healthcare expenditure. Methods: Using Korean Health Insurance Review and Assessment Service National Patient Samples, we extracted RA patients who used biologic disease modifying anti-rheumatic drugs (bDMARDs) between 2009 and 2018. Descriptive statistics were used to explain the basic features of the data. We calculated the proportion of users of each bDMARD among total patients with bDMARDs half-yearly. We assessed changes in the utilization proportions of bDMARDs including 4 tumor necrosis factor inhibitors (TNFis) and 2 non-TNFis, which have been approved for RA in Korea: etanercept, infliximab, adalimumab, golimumab, tocilizumab, and abatacept, and analyzed the changes in market share of biosimilars among the bDMARDs after their introduction. Overall trends of medical costs for each bDMARD were presented over the 10-year period. Results: Since the introduction of the biosimilar TNFis in 2012, the proportion of their use among bDMARDs steadily increased to 15.8% in 2018. While there has been a gradual increase in the use of biosimilar TNFis, the use of the corresponding originators has been decreasing. The introduction of biosimilar TNFis has resulted in a decrease in the medical costs of patients using either originator or biosimilar TNFis. Conclusion In Korea, the proportional use of biosimilar TNFis has gradually increased since their introduction. The availability of less expensive biosimilar TNFis seems to have brought about a decrease in the medical costs of users of the originators.

Background: Patients with rheumatoid arthritis (RA) undergoing targeted therapy have a higher risk of developing tuberculosis (TB). This requires diagnosis and treatment of latent tuberculosis infection (LTBI). We aimed to evaluate whether diagnosis and treatment of LTBI in RA are effective in Korea, and to estimate the risk of TB development by calculating the incidence rate of active TB among RA patients receiving targeted therapy. Methods: We analyzed data from two prospective cohort studies of RA patients who received biologic disease-modifying antirheumatic drugs (bDMARDs) or Janus kinase (JAK) inhibitor.We selected new starters of targeted therapy and classified them into three groups receiving tumor necrosis factor (TNF) inhibitor, non-TNF inhibitor, and JAK inhibitor, respectively. We then compared LTBI prevalence, treatments, and active TB incidence during first-line therapy in each group. Results: A total of 765 RA patients (574 TNF inhibitor users, 132 non-TNF inhibitor users, and 59 JAK inhibitor users) were included in this study. Observation periods were 1,255.2 personyears (PYs), 264.7 PYs, and 53.3 PYs, respectively. All 765 patients underwent LTBI screening, and the positivity rate was 26.5% (n = 203). Of the 203 LTBI-positive patients, 189 (93.1%) received treatment. Only one patient, who was in the TNF inhibitor group, and was negative for the interferon gamma release assay (IGRA), did not receive LTBI treatment and developed active TB during follow-up. Conclusion Although the prevalence of LTBI in RA patients who started targeted therapy was slightly elevated, the Korean guidelines specifying LTBI screening and treatment were effective in preventing latent TB from becoming active.

Background: We aimed to examine the uptake of infliximab and etanercept biosimilars in patients with rheumatoid arthritis (RA) and its economic implication for healthcare expenditure. Methods: Using Korean Health Insurance Review and Assessment Service National Patient Samples, we extracted RA patients who used biologic disease modifying anti-rheumatic drugs (bDMARDs) between 2009 and 2018. Descriptive statistics were used to explain the basic features of the data. We calculated the proportion of users of each bDMARD among total patients with bDMARDs half-yearly. We assessed changes in the utilization proportions of bDMARDs including 4 tumor necrosis factor inhibitors (TNFis) and 2 non-TNFis, which have been approved for RA in Korea: etanercept, infliximab, adalimumab, golimumab, tocilizumab, and abatacept, and analyzed the changes in market share of biosimilars among the bDMARDs after their introduction. Overall trends of medical costs for each bDMARD were presented over the 10-year period. Results: Since the introduction of the biosimilar TNFis in 2012, the proportion of their use among bDMARDs steadily increased to 15.8% in 2018. While there has been a gradual increase in the use of biosimilar TNFis, the use of the corresponding originators has been decreasing. The introduction of biosimilar TNFis has resulted in a decrease in the medical costs of patients using either originator or biosimilar TNFis. Conclusion In Korea, the proportional use of biosimilar TNFis has gradually increased since their introduction. The availability of less expensive biosimilar TNFis seems to have brought about a decrease in the medical costs of users of the originators.

Background: In this study, we aimed to evaluate and compare the treatment indication for patients with glucocorticoid-induced osteoporosis (GIOP) in various clinical practice guidelines. Methods: We searched for potentially relevant studies conducted from January 2000 to March 2020 using online databases, including PubMed, Ovid-EMBASE, Guidelines International Network, National Institute for Health and Clinical Excellence, KoreaMed, KMbase, and KoMGI. We reviewed and analyzed the guidelines that included recommendations on GIOP and fulfilled the inclusion criteria. Results: A total of 94 articles were selected based on review of the title and abstract; 14 guidelines were assessed upon reviewing the full text. The bone mineral density score for therapeutic intervention of GIOP in postmenopausal women was presented in 7 guidelines, among which 3 guidelines set a T-score of −2.5 or lower and the other 4 guidelines proposed a less stringent cut-off point of −1.5 or lower. Among the 10 guidelines published since 2012 after the emergence of the fracture risk assessment tool (FRAX), 6 guidelines included FRAX in their criteria for defining intervention thresholds. However, they were further divided into fixed-probability (n=3) and age-dependent (n=3) thresholds based on the country. Conclusions Recently developed guidelines use FRAX as the criterion for establishing the treatment of patients with GIOP. However, these intervention thresholds need to be adapted for each country.