Cost-of-illness changes before and after the diagnosis of systemic lupus erythematosus: a nationwide, population-based observational study in Korea.

OBJECTIVES: To estimate the direct healthcare cost progression from before to after systemic lupus erythematosus (SLE) diagnosis and to compare healthcare costs by disease severity. METHODS: Patients with incident SLE diagnosed between 2008 and 2018 were identified from the Korean National Health Insurance database. Annual direct healthcare costs for 5 years before and after SLE were estimated and compared with those of age-, sex-, and calendar month-matched (1:4) controls, without SLE. Direct healthcare costs were compared by disease severity of SLE using regression analysis. RESULTS: Among 11 173 patients with SLE and 45 500 subjects without SLE, annual direct healthcare costs per person increased in the year before SLE diagnosis and peaked in the first year after diagnosis. They were 7.7-fold greater in the SLE patients than in the subjects without SLE ($5,871 vs $759). Severe SLE was associated with 3.284-fold (95% CI 3.075-3.507) higher annual costs than mild SLE during the year after diagnosis. Older age (age 60-79 years), lupus nephritis, interstitial lung diseases, and comorbidities such as avascular necrosis and chronic kidney disease were associated with higher annual direct healthcare costs (times [95% CI]) in the first year after diagnosis; aged 60-69, 1.119 [1.034-1.211], aged 70-79, 1.470 [1.342-1.611], 1.794 [1.711-1.881], 1.435 [1.258-1.638], 6.208 [4.541-8.487], and 1.858 [1.673-2.064], respectively. CONCLUSION: Patients with SLE incurred significantly high direct healthcare costs than subjects without SLE during the first year after diagnosis. Disease severity, older age, major organ involvements and comorbidities were associated with increased healthcare costs.

Korean LupusPRO: Cross-Cultural validation study for systemic lupus erythematosus.

OBJECTIVE: To establish the reliability and validity of the Korean version of LupusPRO version 1.7 (v1.7) for systemic lupus erythematosus (SLE) patients. METHODS: LupusPRO v1.7 was translated into Korean, followed by pretesting among five native Korean speakers. We administered the LupusPRO v1.7 survey to five SLE patients and made minor changes to clarify the language. Then, 133 SLE patients participated in the validation procedure. In each domain, the internal consistency reliability (ICR) and test-retest reliability (TRR) were assessed using Cronbach's alpha and the intra-class correlation coefficient (ICC), respectively. Criterion validity was evaluated using Spearman's correlation coefficient with the other measures such as SF-36, EQ-5D VAS, and SELENA-SLEDAI PGA. Construct validity was assessed by confirmatory factor analysis (CFA) using the unweighted least square estimation method. RESULTS: The mean age of the 133 patients was 36.14 years, and 97% of them were women. Analysis of 130 returned questionnaires revealed that most ICRs of the Korean LupusPRO v1.7 domains were acceptable, with Cronbach's alphas in the range of 0.579-0.949, and most TRRs were good with ICCs from 0.582 to 0.851. Criterion validities presented significant correlations between the LupusPRO v1.7 and other measures validated. In the analysis of the CFA model, the goodness of fit indices demonstrated an acceptable fit. Factor loadings for most individual items were between 0.548 and 0.985. The average variance extracted (AVE) and composite reliability (CR) of most domains were greater than 0.5 and 0.7, respectively, demonstrating acceptable convergent and discriminant validities. CONCLUSIONS: The Korean version of LupusPRO v.17 had acceptable reliability and validity.

COX-2 Inhibitor Use as an Early Treatment Option for Knee Osteoarthritis Patients in Korea: A Population-Based Cross-Sectional Study.

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.

Uptake of Biosimilars and Its Economic Implication for the Treatment of Patients with Rheumatoid Arthritis in Korea.

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.

Risk of Tuberculosis Development in Patients with Rheumatoid Arthritis Receiving Targeted Therapy: a Prospective Single Center Cohort Study.

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 person-years (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.

The Prevalence of Sjögren's Syndrome in Rheumatoid Arthritis Patients and Their Clinical Features.

BACKGROUND: To estimate the prevalence of Sjögren's syndrome (SS) in patients with rheumatoid arthritis (RA) and to compare the clinical features of RA patients with and without SS. METHODS: We conducted a retrospective study of RA patients who visited a rheumatology clinic in a tertiary referral hospital in Korea between May 20 and July 22, 2016. All patients fulfilled the classification criteria for RA, and the diagnosis of SS was made clinically by rheumatologists and according to the 2002 American-European Consensus Group (AECG), 2012 American College of Rheumatology (ACR), and 2016 ACR/European League Against Rheumatism (EULAR) classification criteria. The prevalence was estimated as the number of SS patients within the total number of RA patients. The disease activity and treatment pattern of RA were compared between patients with and without SS. RESULTS: Among 827 RA patients, 72 patients (8.7%) were diagnosed with SS by a rheumatologist, though only 60 patients (7.3%) satisfied the 2002 AECG classification criteria for SS. Fifty-two patients (6.3%) and 56 patients (6.8%) fulfilled the 2012 ACR and 2016 ACR/EULAR classification criteria, respectively. The prevalence of SS in RA patients was 10.5%, 17.0%, and 67.6% in rheumatoid factor, antinuclear antibody (≥ 1:80), and anti-Ro antibody positive patients, respectively. CONCLUSION: The prevalence of SS among RA patients was 8.7% according to rheumatologists' diagnosis. The presence of SS did not affect the treatment patterns of RA patients. However, the autoantibody profiles and demographics of RA patients with SS differed from those of patients without SS.

Increased risk of malignancy in patients aged over 50 with idiopathic inflammatory myositis compared to patients with osteoarthritis of the knee.

Objectives: To estimate risk of malignancy in patients with idiopathic inflammatory myositis (IIM) compared to patients with knee osteoarthritis (OA).Methods: Patients with IIM and knee OA aged over 50, who had no history of malignancy, were identified using Korean National claims database from January 2012 to December 2014. They had been observed until a malignancy was diagnosed or up to the end of the study, December 2015. The incidence rate (IR) of malignancy in IIM patients was calculated and compared with knee OA patients using standardized incidence ratio (SIR).Results: A total of 634 polymyositis (PM) and 556 dermatomyositis (DM) patients were included. Overall, 100 solid (IR 270.4/10,000 person-years (PY), 95% confidence interval (CI) 217.4-323.4) and 12 hematologic malignancies (IR 32.4/10,000 PY, 95% CI 14.1-50.8) occurred. Compared with knee OA, risk of overall (SIR 1.5, 95% CI 1.2-1.8), solid (SIR 1.4, 95% CI 1.1-1.6), and hematologic malignancy (SIR 5.7, 95% CI 2.5-9.0) were increased in IIM patients. This was due to increased incidence of malignancy in DM (hematologic malignancy, SIR 8.7, 95% CI 2.7-14.7, solid malignancy, SIR 1.5, 95% CI 1.1-1.9).Conclusion: Patients with IIM, especially DM, have an increased risk of malignancy compared to patients with knee OA.

Malignancy risk in Korean male patients with ankylosing spondylitis.

The objective of this study is to determine the overall and specific cancer risks in male patients with ankylosing spondylitis (AS). From the claims database of the Health Insurance and Review Assessment, male patients with AS without prior cancer history were selected (n = 21,780). Stratified random samples of claims data were used as a reference general male population group (n = 342,361). Incidence rates of overall and types of cancer were presented as number of events per 10,000 person-years with 95% confidence interval (CI). A standardized incidence ratio (SIR) was used to represent the association between AS and cancer, accounting for person-years at risk. Compared to a general male population group, the overall incidence of cancer was increased in male patients with AS (SIR 1.25, 95% CI 1.15-1.36). For specific malignancy types, the risks of male reproductive system malignancy (SIR 1.97, 95% CI 1.59-2.35) and pancreatic cancer (SIR 1.75, 95% CI 1.12-2.37) were increased. Male patients with AS had increased cancer risk, especially for male reproductive system and pancreatic cancer.

Incidence and Prevalence of Idiopathic Inflammatory Myopathies in Korea: a Nationwide Population-based Study.

BACKGROUND: This study aimed to estimate the incidence and prevalence of idiopathic inflammatory myopathies (IIM) and associated comorbidities in Korea from 2006 to 2015. METHODS: IIM between 2004 to 2015 were identified using the Korean National Health Insurance Service medical claim database. The case definition required more than one visit based on diagnostic codes including juvenile dermatomyositis (JDM), dermatomyositis (DM), or polymyositis (PM) and registration in the Individual Copayment Beneficiaries Program (ICBP) for rare and intractable diseases. IIM patients with a disease-free period of 24 months before the index date were defined as incident cases. The Elixhauser comorbidity score was calculated. RESULTS: Using the base case definition, 1,150 prevalent patients with IIM (117 JDM, 521 DM, 512 PM) were recorded in 2006 and 2,210 (130 JDM, 1,101 DM, 869 PM) in 2015. The prevalence was estimated at 2.3-4.0 (0.9-1.2 for JDM, 1.2-2.7 for DM, 1.4-2.1 for PM)/100,000 person-year (PY). We identified 218 incident cases of IIM in 2006 (18 JDM, 98 DM, 102 PM) and 191 cases (7 JDM, 83 DM, 101 PM) in 2015. The incidence was estimated at 2.9-5.2 (0.7-1.9 for JDM, 1.8-4.0 for DM, 1.6-3.0 for PM)/1,000,000 PY. The mean age (± standard deviation) of prevalent patients with IIM was 51.2 (± 16.9) years, and the percentage of women was 72.1%. More than two-thirds of patients (70.7%) had more than two comorbidities. Twenty percent of patients had interstitial lung diseases. CONCLUSION: In Korea, the incidence and prevalence of IIM were 2.9-5.2/1,000,000 PY and 2.3-4.0/100,000 PY, respectively.

Impact of Osteoarthritis on Household Catastrophic Health Expenditures in Korea.

BACKGROUND: Osteoarthritis (OA) is a disease of old age whose prevalence is increasing. This study explored the impact of OA on household catastrophic health expenditure (CHE) in Korea. METHODS: We used data on 5,200 households from the Korea Health Panel Survey in 2013 and estimated annual living expenses and out-of-pocket (OOP) payments. Household CHE was defined when a household's total OOP health payments exceeded 10%, 20%, 30%, or 40% of the household's capacity to pay. To compare the OOP payments of households with OA individuals and those without OA, OA households were matched 1:1 with households containing a member with other chronic disease such as neoplasm, hypertension, heart disease, cerebrovascular disease, diabetes, or osteoporosis. The impact of OA on CHE was determined by multivariable logistic analysis. RESULTS: A total of 1,289 households were included, and households with and without OA patients paid mean annual OOP payments of $2,789 and $2,607, respectively. The prevalence of household CHE at thresholds of 10%, 20%, 30%, and 40% were higher in households with OA patients than in those without OA patients (P < 0.001). The presence of OA patients in each household contributed significantly to CHE at thresholds of 10% (odds ratio [OR], 1.48; 95% confidence interval [CI], 1.16-1.87), 20% (OR, 1.29; 95% CI, 1.01-1.66), and 30% (OR, 1.37; 95% CI, 1.05-1.78), but not of 40% (OR, 1.17; 95% CI, 0.87-1.57). CONCLUSION: The presence of OA patients in Korean households is significantly related to CHE. Policy makers should try to reduce OOP payments in households with OA patients.

Increased cardiovascular risk in Korean patients with systemic lupus erythematosus: a population-based cohort study.

To determine the increased risk of major adverse cardiovascular events (MACE) in patients with systemic lupus erythematosus (SLE) compared to the general population in Korea. Using data from the National Health Insurance Service database spanning 2008 to 2018, incident SLE patients aged 18 years and above were selected along with a 1:4 age- and sex-matched control group. The crude incidence rate (IR) of MACE was calculated as the number of events per 1000 person-years and the IR ratio (IRR) for MACE was adjusted using generalized estimating equations. Subgroup analysis was conducted to evaluate the risk differences of overall MACE and its composites based on age and sex stratification. The study included 8568 SLE patients and 34,272 controls. The cumulative IR of MACE per 1000 person-years in SLE patients and controls were 4.08 and 1.30, respectively. After adjusting for confounders, SLE patients had a higher risk of MACE compared to the general population (adjusted IRR of 2.40 [95% confidence interval [CI] 1.88-3.05]), with no gender differences observed. The increased risk of MACE in SLE patients was highest in the 18-39 age group (IRR 11.70, 95% CI 5.95-23.01) and gradually decreased with age. The increased risk of ischemic stroke (IRR 2.41, 95% CI 1.84-3.15) and myocardial infarction (IRR 2.19, 95% CI 1.30-3.68) in SLE patients was comparable. The risk of MACE in SLE patients is 2.40 times higher than that of the general population, with a higher relative risk observed in younger individuals.

Risk factors of mortality in patients with rheumatoid arthritis-associated interstitial lung disease: a single-centre prospective cohort study.

OBJECTIVES: To determine the risk factors for mortality in Korean patients with rheumatoid arthritis (RA)-associated interstitial lung disease (ILD) in comparison to patients with RA but without ILD (RA-nonILD). METHODS: Data were extracted from a single-centre prospective cohort of RA patients with a chest computed tomography scan at an academic referral hospital in Korea. Patients with RA-ILD enroled between May 2017 and August 2022 were selected, and those without ILD were selected as comparators. The mortality rate was calculated, and the causes of each death were investigated. We used Cox proportional hazard regression with Firth's penalised likelihood method to identify the risk factors for mortality in patients with RA-ILD. RESULTS: A total of 615 RA patients were included: 200 with ILD and 415 without ILD. In the RA-ILD group, there were 15 deaths over 540.1 person-years (PYs), resulting in mortality rate of 2.78/100 PYs. No deaths were reported in the RA-nonILD group during the 1669.9 PYs. The primary causes of death were infection (nine cases) and lung cancer (five cases), with only one death attributed to ILD aggravation. High RA activity (adjusted HR 1.87, CI 1.16-3.10), baseline diffusing capacity for carbon monoxide (DLCO) < 60% (adjusted HR 4.88, 95% CI 1.11-45.94), and usual interstitial pneumonia (UIP) pattern (adjusted HR 5.13, 95% CI 1.00-57.36) were identified as risk factors for mortality in RA-ILD patients. CONCLUSION: Patients with RA-ILD have an elevated risk of mortality compared with those without ILD. Infection-related deaths are the main causes of mortality in this population. High RA activity, low DLCO, and the UIP pattern are significantly associated with the mortality in patients with RA-ILD.

Risk of end-stage renal disease in patients with early-onset lupus nephritis: A population-based cohort study.

OBJECTIVE: To compare the risk of end-stage renal disease (ESRD) between patients with early-onset lupus nephritis (EOLN) and those with delayed-onset LN (DOLN). METHODS: This retrospective study of incident cases of systemic lupus erythematosus (SLE) used nationwide Korean claims databases and data from 2008 through 2018. We divided LN patients into two groups: the EOLN group (with LN onset within 12 months of SLE diagnoses) and the DOLN group (with LN onset later than 12 months after SLE diagnoses). Patients were observed from the date of LN diagnosis to the development of ESRD, death, or the last follow-up. Cox proportional hazards modeling was used to predict hazard ratios (HRs) for progression to ESRD with death as a competing risk. RESULTS: We identified 3779 incident SLE patients who developed LN during follow-up: 60 % (n = 2281) had EOLN, and 40 % (n = 1489) had DOLN. Sixty-nine patients with EOLN (3.0 %) and 29 patients with DOLN (1.9 %) progressed to ESRD. After adjusting for confounders, the ESRD risk associated with EOLN was comparable to the risk associated with DOLN (HR 1.10, 95 % confidence interval [CI] 0.57 to 2.11). In the subgroup of patients on aggressive immunosuppressive therapy (670 with EOLN and 179 with DOLN), the ESRD risk was higher in the DOLN group (HR 2.6, 95 % CI 1.11 to 6.10). CONCLUSION: The risk of ESRD was comparable between patients with EOLN and DOLN. However, among patients on aggressive immunosuppressive therapy, compared with EOLN, DOLN was associated with a higher risk of progression to ESRD.

Risk of venous thromboembolism in Korean patients with rheumatoid arthritis treated with Janus kinase inhibitors: A nationwide population-based study.

OBJECTIVE: There was a safety concern about an increased risk of thromboembolic events in patients with rheumatoid arthritis (RA) treated with Janus kinase inhibitors (JAKis). This study aimed to determine the risk of venous thromboembolism (VTE) in Korean patients with RA treated with JAKis compared with tumour necrosis factor (TNF) inhibitors. METHODS: Using the National Health Insurance Service database between 2015 and 2019, patients with prevalent RA who started JAKi or TNF inhibitor were selected as the study population. All participants were naïve to targeted therapy. Patients that had experienced any VTE event or used anticoagulant agents within 30 days were excluded. Demographic and clinical characteristics were all balanced by stabilised inverse probability of treatment weighting (sIPTW) using propensity score. The Cox proportional hazard model considering death as a competing risk was used to evaluate the risk of VTE in JAKi users compared with TNF inhibitor users. RESULTS: A total of 4,178 patients were included: 871 JAKi users and 3,307 TNF inhibitor users were followed up for 1,029.2 person-years (PYs) and 5,940.3 PYs, respectively. With a balanced sample after sIPTW, the incidence rates (IR) of VTE were 0.06 per 100 PYs (95% confidence interval [CI] 0.00-1.23) in JAKi users and 0.38 per 100 PYs (95% CI 0.25-0.58) in TNF inhibitor users. The hazard ratio was 0.18 (95% CI 0.01-3.47) after adjusting for unbalanced variables after performing sIPTW. CONCLUSION: There is no increased risk of VTE in RA patients treated with JAKis compared with TNF inhibitors in Korea.

Factors associated with selection of targeted therapy in patients with rheumatoid arthritis.

OBJECTIVE: Deciding which drug to choose for targeted therapy is an important step in sequential treatment for rheumatoid arthritis (RA). This study aimed to identify factors for selecting Janus kinase inhibitors (JAKis) rather than biologic disease-modifying antirheumatic drugs (bDMARDs) in patients with RA in real-world practice. METHODS: We selected RA patients starting JAKis or bDMARDs from single-center prospective cohorts in Korea. Patients were divided into JAKi, tumor necrosis factor (TNF) inhibitor, and non-TNF inhibitor groups. We performed multinomial logistic regression analyses to identify factors associated with selecting JAKis. RESULTS: 145, 205, and 89 patients were included in the JAKi, TNF inhibitor, and non-TNF inhibitor groups. In multinomial regression analysis, the JAKi group was older than the TNF inhibitor group (OR 1.03, 95% confidence interval [CI] 1.01-1.05) but younger than the non-TNF inhibitor group (OR 0.97, CI 0.95-1.00). The JAKi group was less likely to have chronic pulmonary diseases compared with the TNF inhibitor group (OR 0.07, CI 0.01-0.56) or the non-TNF inhibitor group (OR 0.06, CI 0.01-0.50). Higher disease activity assessed by physician (OR 1.80, CI 1.51-2.38) and previous tacrolimus use (OR 2.05, CI 1.20-3.51) were factors suggesting selection of JAKis than TNF inhibitors. CONCLUSION: Age, pulmonary comorbidities, previous tacrolimus use, and high disease activity assessed by physician were factors influencing the selection of JAKis for RA patients in Korea.

Increased risk of herpes zoster with tofacitinib treatment in Korean patients with rheumatoid arthritis: a single-center prospective study.

We aimed to determine the risk of herpes zoster (HZ) in Korean rheumatoid arthritis (RA) patients on tofacitinib compared with tumor necrosis factor inhibitor (TNFi) treatment. From the prospective cohorts of RA patients who started tofacitinib or TNFi in an academic referral hospital in Korea, patients who started tofacitinib between March 2017 and May 2021 and those who started TNFi between July 2011 and May 2021 were included. Baseline characteristics of tofacitinib and TNFi users were balanced through inverse probability of treatment weighting (IPTW) using the propensity score including age, disease activity of RA and medication use. The incidence rate of HZ in each group and incidence rate ratio (IRR) were calculated. A total of 912 patients were included: 200 tofacitinib and 712 TNFi users. There were 20 cases of HZ among tofacitinib users and 36 among TNFi users during observation period of 331.4 person-years (PYs) and 1950.7 PYs, respectively. In IPTW analysis with a balanced sample, IRR of HZ was 8.33 (95% confidence interval 3.05-22.76). Tofacitinib use increased the risk of HZ compared with TNFi in Korean patients with RA, but the rate of serious HZ or permanent discontinuation of tofacitinib due to HZ event was low.

Clinical characteristics of rheumatoid arthritis patients with interstitial lung disease: baseline data of a single-center prospective cohort.

BACKGROUND: To introduce a prospective cohort for rheumatoid arthritis (RA) patients with interstitial lung disease (ILD) and to identify their clinical features in comparison with RA patients without ILD. METHODS: Using a multidisciplinary collaborative approach, a single-center cohort for RA patients with ILD (RA-ILD) was established in May 2017, and enrolment data from May 2017 to March 2021 were used to compare the clinical features of RA patients without ILD (RA-non ILD). Multivariable logistic regression analysis was used to identify factors associated with ILD in RA patients. RESULTS: Among 148 RA-ILD and 410 RA-non ILD patients, participants in the RA-ILD group were older (65.8 ± 9.9 vs. 58.0 ± 10.4 years, P < 0.001) and included more males (35.8% vs. 14.6%, P < 0.001) than in the RA-non ILD group. The RA-ILD group had a higher proportion of late-onset RA patients (age ≥ 60 years) than in the comparator group (43.9% vs. 14.2%, P < 0.001). Multivariable logistic regression analysis showed that higher age at RA onset (OR 1.056, 95% CI 1.021-1.091), higher body mass index (BMI; OR 1.65, 95% CI 1.036-2.629), smoking history (OR 2.484, 95% CI 1.071-5.764), and oral glucocorticoid use (OR 3.562, 95% CI 2.160-5.874) were associated with ILD in RA patients, whereas methotrexate use was less likely to be associated with ILD (OR 0.253, 95% CI 0.155-0.412). CONCLUSIONS: Higher age at RA onset, smoking history, and higher BMI were associated with the presence of ILD among RA patients. Oral glucocorticoids were more frequently used whereas methotrexate was less likely to be used in RA-ILD patients.

Comparative effectiveness of JAK inhibitors and biologic disease-modifying antirheumatic drugs in patients with rheumatoid arthritis.

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. CONCLUSION: Our interim findings reveal JAKi have comparable effectiveness and safety to bDMARDs at 24 weeks after treatment initiation.

Comparative Effectiveness of Azathioprine Versus Cyclosporine as an Initial Treatment for Idiopathic Inflammatory Myopathies: A Population-Based Observational Study.

OBJECTIVE: To compare the effectiveness of azathioprine (AZA) and cyclosporine (CsA) as initial treatments for patients with idiopathic inflammatory myopathies (IIM). METHODS: A retrospective cohort study was conducted using information from the National Health Insurance Service database of Republic of Korea. Patients with IIM who had started AZA or CsA as initial treatment between January 2007 and December 2011 were selected for the study. They were followed from the day of treatment initiation to the occurrence of study outcomes or the end of the study until December 2016. Effectiveness outcomes, defined as switching the drug or adding immunosuppressants, and discontinuation of corticosteroids, were compared between the two groups. The Cox proportional-hazards model was used to calculate the adjusted relative risk (aRR) with 95% confidence interval (CI) between the AZA and CsA groups. RESULTS: A total of 376 patients with incident IIM who used AZA (n = 288) or CsA (n = 88) were identified. The aRR of switching the drug or adding immunosuppressants (1.45 [95% CI 0.99-2.11]) was not significantly different between the CsA and AZA groups. Among patients who were treated with corticosteroids at baseline, the rate of discontinuation of corticosteroids was not different between the two groups (1.69 [95% CI 0.82-3.47]). CONCLUSIONS: The effectiveness of AZA and CsA as initial treatments for the management of IIM was comparable.

Association between malignancy risk and Janus kinase inhibitors versus tumour necrosis factor inhibitors in Korean patients with rheumatoid arthritis: a nationwide population-based study.

OBJECTIVE: To determine the risk of malignancy in Korean patients with rheumatoid arthritis (RA) receiving Janus kinase inhibitors (JAKis) compared with tumour necrosis factor inhibitors (TNFis). METHODS: A retrospective cohort of patients with RA initiating their first JAKi or TNFi was established using the Korean National Health Insurance database between 2015 and 2019. They were followed up from treatment initiation to the occurrence of malignancy, drug discontinuation, death or until December 2019. Baseline features of the patients were balanced through inverse probability of treatment weighting (IPTW) using a propensity score. A Cox proportional hazard model was established to estimate the HR for malignancy risk in JAKi users compared with TNFi users. RESULTS: A total of 4929 patients (1064 JAKi-treated and 3865 TNFi-treated patients) were included, and the observation periods were 1288.6 person-years (PYs) for JAKi users and 6823.8 PYs for TNFi users. The incidence rates of overall malignancy were 0.54 per 100 PYs (95% CI 0.26 to 1.14) in JAKi users and 0.85 per 100 PYs (95% CI 0.66 to 1.10) in TNFi users. In IPTW analysis with a balanced sample (4101 JAKi-treated and 5131 TNFi-treated patients), HR was 0.83 (95% CI 0.55 to 1.27) for overall malignancy: 0.77 (95% CI 0.50 to 1.19) for solid malignancy and 2.86 (95% CI 0.41 to 20.00) for haematological malignancy. CONCLUSION: Malignancy risk in Korean patients with RA was not increased with JAKi use compared with TNFi use.