Abstract 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.

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

Systemic lupus erythematosus (SLE) is an autoimmune disorder that can affect various organs. Juvenile-onset SLE (jSLE) may be more severe than the adult-onset form, but the diagnosis and classification remain challenging due to the complex nature of the condition and its resemblance to other conditions. Antinuclear antibodies (ANA) are the immunological hallmark of SLE, but their limited specificity poses challenges. The 2019 (European Alliance of Associations for Rheumatology/American College of Rheumatology) SLE proposed a weighted multi-criteria system for classifying SLE, with ANA serving as an entry criterion. However, seronegative SLE, in which a patient's clinical features and laboratory values are consistent with SLE but their ANA serology test is negative, is a rare subtype of SLE that has been reported in several cases worldwide. Here, we present two rare cases of jSLE in 13- and 11 years old girls with negative ANA. The first case presented as lupus cerebritis and lupus nephritis (LN) class IV and V which showed improvement with treatment. The other one was also diagnosed as LN class IV but showed poor outcome despite aggressive immunosuppressive treatment. These cases highlight the importance of considering lupus-like symptoms in children with negative serology and the need for further research into current diagnostic protocols and calls for a re-evaluation using a more inclusive set of criteria that does not centralize immunological serology.

The management of rheumatoid arthritis (RA) follows a treat-to-target approach, as recommended by guidelines from the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR).RA treatment recommendations include an emphasis on frequent disease activity assessments to optimize therapy, recognizing the possibility of timely therapies to slow progression and improve long-term results.The evaluation of joint inflammation, pain, physical function, and clinical indicators is required for comprehensive RA therapy.Current therapeutic goals include achieving low disease activity or remission to enhance the quality of life (QoL) for patients.ACR-endorsed RA disease activity measures, such as the Disease Activity Score in 28 Joints with erythrocyte sedimentation rate or C-reactive protein level, Simplified Disease Activity Index (SDAI), Clinical Disease Activity Index (CDAI), Patient Activity Scale-II, and Routine Assessment of Patient Index Data 3, are recommended for their precision and sensitivity in supporting treat-to-target strategies.The ACR and EULAR have implemented Boolean-based and index-based remission criteria (SDAI and CDAI, respectively) to evaluate therapeutic effectiveness.The use of these markers regularly aligns with the ACR guidelines, improving adherence to quality indicators in clinical practice and confirming the provision of high-quality RA therapy.This review examines disease activity, function, and QoL measurements in line with the ACR and EULAR guidelines to aid doctors in treating Korean patients with RA.

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

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.

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.

Gout is the most common form of arthritis, with the prevalence increasing worldwide. The present treatment guidelines provide recommendations for the appropriate treatment of acute gout, management during the inter-critical period, and prevention of chronic complications. The guidelines were developed based on evidence-based medicine and draft recommendations finalized after expert consensus. These guidelines are designed to provide clinicians with clinical evidence to enable efficient treatment of gout.

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.

Objective To determine the risk of herpes zoster (HZ) in Korean patients with rheumatoid arthritis (RA) receiving Janus kinase inhibitors (JAKis). Methods We performed a nested case–control study with 1:10 matching for sex and age using single-centre prospective cohorts of patients with RA receiving targeted therapy in Korea. Then we performed conditional logistic regression analyses to determine the risk associated with JAKi use compared with biologic disease-modifying antirheumatic drug (bDMARD) use, with adjusting for various factors. We also used logistic regression analysis to identify other risk factors for the development of HZ in JAKi users. Results From a total of 1147 patients, 61 cases and 610 matched controls were selected. In conditional logistic regression analysis, JAKi use did not increase the risk of HZ development (OR 1.35, 95% CI 0.70 to 2.61) after adjusting for other factors. Rather, duration of RA less than 10 years (OR 0.54, 95% CI 0.30 to 0.97) and having had three or more previous targeted therapies (OR 5.29, 95% CI 1.45 to 19.31) were risk factors for HZ. Among JAKi users, higher disease activity score 28-erythrocyte sedimentation rate (DAS28-ESR) (OR 1.44, 95% CI 1.06 to 1.97) was identified as a risk factor in addition to three or more previous targeted therapies (OR 10.12, 95% CI 1.92 to 53.49). Conclusions The number of previous targeted therapies, but not JAKi use, was identified as a risk factor for HZ development in Korean patients with RA in a real-world setting. High disease activity was an additional risk factor for JAKi users.

Sang-Hyon Kim, M.D., Ph.D., Ji-Hyun Lee, M.S., Hye-Jin Jeong, M.D., Ji-Min Kim, M.D., Ph.D., Won-Ki Baek, M.D., Ph.D., Tae-Hwan Kim, M.D., Ph.D., Jae-Bum Jun, M.D., Ph.D., and Chang-Nam Son, M.D., Ph.D.. Ann Lab Med 2022;42:293-5. https://doi.org/10.3343/alm.2022.42.2.293

Serum uric acid levels are altered by kidney disorders because the kidneys play a dominant role in uric acid excretion. Here, major kidney disorders which accompany hyperuricemia or hypouricemia, including their pathophysiology, are discussed. Chronic kidney disease (CKD) and hyperuricemia are frequently associated, but recent clinical trials have not supported the pathogenic roles of hyperuricemia in CKD incidence and progression. Diabetes mellitus (DM) is often associated with hyperuricemia, and hyperuricemia may be associated with an increased risk of diabetic kidney disease in patients with type 2 DM. Sodium-glucose cotransporter 2 inhibitors have a uricosuric effect and can relieve hyperuricemia in DM. Autosomal dominant tubulointerstitial kidney disease (ADTKD) is an important hereditary kidney disease, mainly caused by mutations of uromodulin (UMOD) or mucin-1 (MUC-1). Hyperuricemia and gout are the major clinical manifestations of ADTKD-UMOD and ADTKD-MUC1. Renal hypouricemia is caused by URAT1 or GLUT9 loss-of-function mutations and renders patients susceptible to exercise-induced acute kidney injury, probably because of excessive urinary uric acid excretion. Hypouricemia derived from renal uric acid wasting is a component of Fanconi syndrome, which can be hereditary or acquired. During treatment for human immunodeficiency virus, hepatitis B or cytomegalovirus, tenofovir, adefovir, and cidofovir may cause drug-induced renal Fanconi syndrome. In coronavirus disease 2019, hypouricemia due to proximal tubular injury is related to disease severity, including respiratory failure. Finally, serum uric acid and the fractional excretion of uric acid are indicative of plasma volume status; hyperuricemia caused by the enhanced uric acid reabsorption can be induced by volume depletion, and hypouricemia caused by an increased fractional excretion of uric acid is the characteristic finding in syndromes of inappropriate anti-diuresis, cerebral/renal salt wasting, and thiazide-induced hyponatremia. Molecular mechanisms by which uric acid transport is dysregulated in volume or water balance disorders need to be investigated.

Objective:Both hypouricemia and hyperuricemia are reportedly associated with reduced kidney function This study investigated the association between uric acid levels and the risk of reduced renal function in men and women.Methods:We conducted a cross-sectional study using data from a government-funded health examinee cohort of a Korean genome and epidemiological study A total of 172,970 participants (58,981 men, 113,989 women) aged 40∼79 years were included A logistic regression test was performed, and the odds ratio (OR) and 95% confidence interval (CI) were calculated to examine the relationship between stratified uric acid levels and the frequency of chronic kidney disease.Results:As the uric acid level increased, the risk of reduced renal function increased Moreover, for uric acid levels ≤20 mg/dL, the risk of reduced renal function was higher than that of the reference group Among the total, man, and woman groups, a statistically significant association was observed in men (OR 171, 95% CI 0945∼3111, OR 5003, 95% CI 1405∼17809, and OR 1377, 95% CI 0696∼2724, respectively).Conclusion:The OR of reduced renal function according to uric acid levels formed a J-shaped curve in both genders.

Background/Aims We investigated the distribution of serum uric acid (SUA) levels and estimated the prevalence of hyperuricemia and hypouricemia in the Korean population. Methods This cross-sectional study used data from the Korean Genome and Epidemiology Study and included 172,970 participants (58,981 men and 113,989 women) aged 40 to 79 years. Hypouricemia and hyperuricemia were defined as SUA level ≤ 2.0 mg/dL and > 7 mg/dL, respectively. The prevalence of hyperuricemia and hypouricemia was evaluated by age and sex. Results The mean SUA levels were significantly higher in men than in women (5.71 ± 1.27 mg/dL vs. 4.21 ± 0.96 mg/dL, p < 0.001). The mean SUA levels and prevalence of hyperuricemia increased with age in women but not in men. The overall prevalence of hyperuricemia and that in men and women was 50.82, 133.25, and 8.17 per 1,000 persons, respectively; the overall prevalence of hypouricemia and that in men and women was 4.16, 1.10, and 5.75 per 1,000 persons, respectively. The prevalence of hypouricemia in men was similar across all age groups; however, that in women was the highest in the age group of 40 to 49 years and the lowest in the age group of 50 to 59 years. Conclusions The distribution of SUA levels and prevalence of hyperuricemia and hypouricemia differed according to age and sex. Age and sex should be considered in studies on uric acid-related diseases.

Background This study aimed to analyze the literature systematically to determine the clinical characteristics and prognosis of patients with connective tissue disease (CTD) with combined pulmonary fibrosis and emphysema (CPFE) compared to those of patients with CTD-interstitial lung disease (CTD-ILD) without emphysema. Methods We searched MEDLINE, EMBASE, Cochrane Library, and KoreaMed for relevant articles published before July 2019. Studies meeting all the following criteria were included: (1) original research studies evaluating the effect of CPFE on CTD, (2) studies that compared patients with CTD-CPFE to those with CTD-ILD without emphysema, and (3) studies providing data on physical capacity, pulmonary function, or death in patients with CTD. Clinical characteristics of patients with CTD-CPFE were compared with those of patients with CTD-ILD without emphysema, and the influence of CPFE on physical capacity, pulmonary function, and death was analyzed. Results Six studies between 2013 and 2019 were included. Two hundred ninety-nine (29.5%) and 715 (70.5%) patients had CTD-CPFE and CTD-ILD without emphysema, respectively. Regarding the type of CTD, 711 (68.3%) patients had systemic sclerosis, 263 (25.3%) rheumatoid arthritis, and 67 (6.4%) other CTDs. Patients with CTD-CPFE had a higher frequency of pulmonary hypertension and pulmonary fibrosis > 20% of the total lung volume, higher ratio of the forced vital capacity to the diffusion capacity of the lung for carbon monoxide (DLCO), lower arterial oxygen pressure at rest, and lower DLCO compared to those in patients with CTD-ILD without emphysema. In addition, more deaths occurred among those with CTD-CPFE (odds ratio, 2.95; 95% confidence interval, 1.75–4.96). Conclusion CTD-CPFE is associated with worse physical and pulmonary function and more deaths compared to those in CTD-ILD without emphysema. These findings indicate the need for increased awareness and close monitoring of patients with CTD-CPFE.

Objectives To assess the efficacy of an endothelin receptor antagonist (ERA) and phosphodiesterase type5 inhibitors (PDE5is) for treating SSc-related digital ulcers (DUs). Methods This prospective, multicentre, observational cohort study recruited patients with active SSc-related DUs from 13 medical centres in South Korea. The primary outcome was time to cardinal ulcer (CU) healing. A secondary outcome was time to new DU occurrence. Patients were followed up 4, 8, 12 and 24 weeks after treatment initiation. Results Sixty-three patients were analysed. Their mean age was 49.9 years (s.d. 11.4) and 49 were female. Twenty-eight had limited SSc. Forty-nine patients received ERA, 11 received a PDE5i (9 sildenafil, 1 udenafil and 1 tadalafil) and 3 received other medication. The hazard ratio (HR) for time to CU healing in the ERA group vs the PDE5i group was 0.75 (95% CI 0.35, 1.64; P = 0.47) in an unadjusted model and 0.80 (95% CI 0.36, 1.78; P = 0.59) in a model adjusted for age, sex, use of calcium channel blockers (CCBs), total DU number and initial CU area. The HR for new DU development in the ERA group vs the PDE5i group was 0.39 (95% CI 0.16, 0.93; P = 0.03) in an unadjusted model and 0.32 (95% CI 0.13, 0.81; P = 0.02) in an adjusted model. No patients receiving CCBs developed new DUs at 24 weeks. Conclusion Time to CU healing is comparable for ERA and PDE5i. ERAs are more effective in reducing new DU occurrence than PDE5is. CCBs may be effective as a background medication.

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

The clinical relevance of the fabella, a sesamoid bone, has recently been investigated. Although many studies have documented the prevalence of the fabella, few large-scale studies have been conducted in an Asian, especially Korean, population. We conducted a retrospective survey of Koreans to determine the prevalence and distribution of the fabella and its association with osteoarthritic severity of the knee. From June 2016 to August 2017, a total of 2243 people who visited a rheumatology clinic for musculoskeletal evaluation was consecutively recruited. A total of 2126 subjects (1634 females and 492 males) was finally registered and analysed. Anteroposterior and lateral radiographs of both knees were analysed for presence, number and distribution of fabellae and Kellgren-Lawrence grade. The prevalence of the fabella was 57.2% (57.5% for females, 56.1% for males). Among subjects with a fabella, 21.2% had a unilateral distribution, and 78.8% had a bilateral distribution. The number of fabella was correlated with increasing age (r = 0.169, p < 0.001). In the group of subjects with a fabella, the Kellgren-Lawrence grade was significantly higher than in the group without a fabella (2.64 ± 1.38 vs. 1.89 ± 1.54, p < 0.001). The prevalence of fabella in Koreans was relatively high compared with the findings of previous studies, irrespective of the country studied or methodology used. The number of fabellae tended to increase with age. The osteoarthritic severity of the knee appeared worse in the group with a fabella.

In an elderly population with cognitive impairment, we investigated the association between serum uric acid (sUA) and serum homocysteine (sHcy), known risk factors for cerebrovascular disease. We also investigated the potential effect of the C677T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR) to the sUA level in different dementia types. Participants underwent a battery of tests including measurements of sUA, sHcy, folic acid, and vitamin B12 as well as genotyping of the MTHFR locus. Data from 861 subjects (597 females to 264 males) were retrospectively analyzed. Subjects with hyperhomocysteinemia had lower serum folic acid and vitamin B12 and higher sUA than those with normal sHcy. sUA was significantly associated with serum creatinine, HbA1c, and sHcy regardless of gender. The TT genotype was found to be associated with hyperhomocysteinemia in both genders (p = 0.001). The levels of hyperlipidemia, sHcy, and sUA differed according to dementia subtypes. High sUA were associated with hyperhomocystenemia in TT genotype only in dementia with vascular lesion. This study reveals that sUA is positively associated with sHcy. We speculate that the two markers synergistically increase cerebrovascular burden and suggested that dietary intervention for sUA and sHcy would be helpful for cognitive decline with vascular lesion.