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This study aimed to analyse the clinical features and outcomes of and reasons for discontinuing tumour necrosis factor (TNF) inhibitor therapy in older patients with ankylosing spondylitis (AS).Data were extracted from the nationwide Korean College of Rheumatology Biologics registry. Clinical variables and outcomes were compared, and drug retention rate was evaluated.Among 1524 patients with AS treated with TNF inhibitors, 306 were aged ≥ 50 years ('older patients'). Fewer patients were male, the incidence of hypertension and diabetes was higher (all p0.001), and the proportion of peripheral arthritis (35.6 vs. 27.1%), Ankylosing Spondylitis Disease Activity Score‒erythrocyte sedimentation rate (4.0 ± 1.1 vs. 3.6 ± 1.0), and Bath Ankylosing Spondylitis Functional Index (4.2 ± 2.6 vs. 3.3 ± 2.5) were all higher in older patients. Although the drug retention rate was lower (log-rank p = 0.018) and lack of efficacy and adverse events were more frequent in older patients (both p0.001), drug retention rates were not different after propensity score matching (log-rank p = 0.23). Improvements in disease activity and manifestations were comparable between groups, except for the incidence of peripheral arthritis, which decreased significantly less in older patients over 3 and 5 years.Improvements in disease-related clinical factors and drug retention rates were not different between older and younger patients with AS receiving TNF inhibitors. However, the incidence of adverse events was higher in older patients.

The upheaval caused by the coronavirus disease 2019 (COVID-19) pandemic has allowed to large population to use new vaccines urgently. Although vaccine development programs and available epidemiological data reassure us, there are concerns about specific risks associated with vaccinations in patients with autoimmune-autoinflammatory diseases. These patients have the potential to decrease humoral and cellular immune responses caused by biologic agents and develop an acute flare of underlying disease following vaccination. We herein present a rare case of a 49-year-old female with a flare of adult-onset Still's disease (AOSD) after the first dose of BNT162b2 mRNA COVID-19 vaccination. She had been diagnosed with AOSD 7 years earlier and had achieved remission with tocilizumab. This patient came to the emergency room with fever and nausea that occurred 4 days after the first vaccination. Based on laboratory results and clinical manifestations, we suspected AOSD flare and was treated with steroid pulse therapy. In this report, we also discuss possible mechanisms linking vaccination with a flare of AOSD. Considering the close time relationship between COVID-19 vaccinations and a flare of AOSD, physicians should be aware of adverse events from this new vaccination and evaluate the benefits and risks of vaccination for each patient. KEY POINTS: • COVID-19 vaccination may cause an AOSD flare in patients who are in remission with tocilizumab.

Toll-like receptor (TLR)-4 and TLR9 are known to play important roles in the immune system, and several studies have shown their association with the development of rheumatoid arthritis (RA) and regulation of tumor necrosis factor alpha (TNF-α). However, studies that investigate the association between TLR4 or TLR9 gene polymorphisms and remission of the disease in RA patients taking TNF-α inhibitors have yet to be conducted. In this context, this study was designed to investigate the effects of polymorphisms in TLR4 and TLR9 on response to TNF-α inhibitors and to train various models using machine learning approaches to predict remission. A total of six single nucleotide polymorphisms (SNPs) were investigated. Logistic regression analysis was used to investigate the association between genetic polymorphisms and response to treatment. Various machine learning methods were utilized for prediction of remission. After adjusting for covariates, the rate of remission of T-allele carriers of TLR9 rs352139 was about 5 times that of the CC-genotype carriers (95% confidence interval (CI) 1.325–19.231, p = 0.018). Among machine learning algorithms, multivariate logistic regression and elastic net showed the best prediction with the area under the receiver-operating curve (AUROC) value of 0.71 (95% CI 0.597–0.823 for both models). This study showed an association between a TLR9 polymorphism (rs352139) and treatment response in RA patients receiving TNF-α inhibitors. Moreover, this study utilized various machine learning methods for prediction, among which the elastic net provided the best model for remission prediction.

Objectives Nuclear factor of activated T cells C2 (NFATC2) is known as a member of the transcription family and enhances tumor necrosis factor-alpha (TNF-α) synthesis in human T cells at the gene transcription level. Although NFATC2 has a potential role in rheumatoid arthritis (RA) progression and treatment, no study has investigated the association between NFATC2 gene polymorphisms and response status in RA patients receiving TNF-α inhibitors. This study aimed to examine the effects of polymorphisms in NFATC2, a TNF-α transcription factor, on response to TNF-α inhibitors. Methods This prospective observational study was performed in two centers. Seven single nucleotide polymorphisms (SNPs) were investigated. Good responders were defined as patients with disease activity score (DAS)28 ≤3.2 after 6 months of treatment. Logistic regression analyses were used to investigate the association between genetic polymorphisms and response to the treatment. To test the model's goodness of fit, a Hosmer-Lemeshow test was performed. Results This study included 98 patients, among whom 46 showed favorable responses to the treatment. Patients with hypertension revealed an approximately three-fold lower response to TNF-α inhibitors compared to those without hypertension (23.5 vs. 76.5%; P = 0.049). After adjusting for covariates, C allele carriers of NFATC2 rs3787186 exhibited approximately three-fold lower rates of treatment response compared to those with TT genotype (P = 0.037). The Hosmer-Lemeshow test showed that the fitness of the multivariable analysis model was satisfactory (χ2 = 9.745; 8 degrees of freedom; P = 0.283). Conclusion This study suggested an association between the C allele of rs3787186 and treatment response in RA patients receiving TNF-α inhibitors.

Immunoglobulin gamma-3 chain C (IGHG3) levels have been detected in the blood and tissue of patients with systemic lupus erythematosus (SLE). This study aims to assess its clinical value by measuring and comparing levels of IGHG3 in different body fluids in patients with SLE. The levels of IGHG3 in saliva, serum, and urine from 181 patients with SLE and 99 healthy controls were measured and analyzed. In patients with SLE and healthy controls, salivary IGHG3 levels were 3078.9 ± 2473.8 and 1413.6 ± 1075.3 ng/mL, serum IGHG3 levels were 478.1 ± 160.9 and 364.4 ± 97.9 μg/mL, and urine IGHG3 levels were 64.0 ± 74.5 and 27.1 ± 16.2 ng/mL, respectively (all p < 0.001). Salivary IGHG3 was correlated with ESR (correlation coefficient [r], 0.173; p = 0.024). Serum IGHG3 was correlated with leukocyte count (r, −0.219; p = 0.003), lymphocyte count (r, 0.22; p = 0.03), anti-dsDNA antibody positivity (r, 0.22; p = 0.003), and C3 levels (r, −0.23; p = 0.002). Urinary IGHG3 was correlated with hemoglobin level (r, −0.183; p = 0.021), ESR (r, 0.204; p = 0.01), anti-dsDNA antibody positivity (r, 0.262; p = 0.001), C3 levels (r, −0.202; p = 0.011), and SLE disease activity index (r, 0.332; p = 0.01). Urinary IGHG3 was higher in patients with nephritis than in those without (119.5 ± 110.0 vs. 49.8 ± 54.4 ng/mL; p < 0.01). IGHG3 was increased in the saliva, serum, and urine of patients with SLE. While salivary IGHG3 was not identified to be specific to SLE disease activity, serum IGHG3 showed correlations with clinical characteristics. Urinary IGHG3 levels were associated with disease activity and renal involvement in SLE.

Transcription of the chemerin chemokine-like receptor 1 (CMKLR1) has been observed in T cell subsets, but its role in T cells has not been well studied. As previously reported, the levels of its ligand, chemerin, are increased in the plasma and synovial fluid of patients with rheumatoid arthritis (RA); hence, we aimed to explore the expression and role of CMKLR1 in the T cells of these patients.Peripheral blood and synovial fluid from patients with RA or osteoarthritis and healthy individuals were collected to analyse the frequency of CD27-CD28- T cells and the expression of CMKLR1 and TNF-α by flow cytometry. Chemotaxis of T cells was assessed using a Transwell migration assay. Chemerin levels were measured using an enzyme-linked immunosorbent assay.CMKLR1 was preferentially expressed in CD27-CD28- T cell subsets. Its surface levels were reduced by stimulation with anti-CD3 antibody or chemerin. We found a correlation between CMKLR1+CD8+CD27-CD28- T cell frequency and disease activity score 28 of RA. Chemerin treatment up-regulated but CMKLR1 inhibitor treatment down-regulated TNF-α expression in CD8+CD27-CD28- T cells, half of which express CMKLR1 on average. Moreover, chemerin induced migration of these cells. Analysis of blood and synovial fluid samples of RA showed a reduction of CMKLR1+CD27-CD28- T cell levels in the synovial fluid, with a few exceptions.Our results suggest that CMKLR1 expression in T cells may be involved in RA pathogenesis through modulation of TNF-α expression and cell migration.

Background: We investigated the prevalence of and the factors associated with a high risk of osteoporotic fractures in Korean patients with ankylosing spondylitis (AS). Methods: This was a multicenter, retrospective study including 219 AS patients from five university hospitals; the control group was selected by matching age and sex with those of the AS patients. The fracture risk was evaluated based on bone mineral density (BMD) measured by dual-energy X-ray absorptiometry and the fracture risk assessment tool (FRAX) with/without BMD. Results: The mean age of the patients was 47.6 years, and 144 (65.8%) patients were men. According to the WHO criteria and FRAX with/without BMD, the candidates for pharmacological treatment were 44 (20.1%), 20 (13.2%), and 23 (15.1%) patients, respectively, significantly more than those in the healthy control group. Among them, the proportion of patients receiving osteoporosis treatment was 39.1–75%. In logistic regression analysis, menopause was an independent factor for the high risk of fracture according to the WHO criteria and FRAX with/without BMD. C-reactive protein level (odds ratio (OR) 3.8 and OR 6) and glucocorticoid use (OR 1.5 and OR 1.7) were associated with a high risk of osteoporotic fracture based on FRAX without BMD and osteoporosis diagnosed according to the WHO criteria. Conclusions: Our study suggests that both FRAX and WHO criteria may be complementary for treatment decisions to reduce osteoporotic fractures in patients with AS.

Our aim was to evaluate the association between salivary gland scintigraphy and the clinical parameters, including histological characteristics of salivary glands, in patients with primary Sjogren's syndrome (pSS).Forty-one pSS patients were included in the study. The patients who had received salivary gland scintigraphy and minor salivary gland biopsy were retrospectively analyzed. Salivary gland scintigraphy was interpreted via semi-quantitative methods obtained by calculating the peak uptake and washout of each gland using regions of interest. All specimens were examined by pathologists for focus scores and leukocyte common antigen (LCA) to determine the degree of inflammatory infiltration.The mean age of pSS patients was 46.4 years, 82.9% were female, and the mean duration of symptoms was 2.5 years. The focus score was negatively correlated to the mean peak uptake (r = ‒0.396; p = 0.019), mean uptake (r = ‒0.388; p = 0.021), and mean percentage washout (r = ‒0.391; p = 0.02). In addition, the focus score and number of LCA positive cells per mmAlthough the diagnostic role of salivary gland biopsy is widely accepted and features in the classification criteria of Sjogren's syndrome, salivary gland scintigraphy may be an acceptable alternative method especially if a non-invasive test is required.

Polymyalgia rheumatica (PMR), a benign rheumatic disorder, requires long-term glucocorticoid therapy, which could be associated with osteoporosis. In the present study, we compared bone mineral density (BMD), trabecular bone score (TBS) and frequencies of vertebral fracture (VF) among patients with PMR or rheumatoid arthritis (RA) and controls.Fifty-three postmenopausal women with PMR aged 50 yr or older were eligible for inclusion in this study. Subjects in RA (n = 106) and control (n = 106) groups were selected by propensity score matching with controlling age, body mass index and use of anti-osteoporotic agents.The frequency of VF in patients with PMR (30.2%) was significantly higher than those in patients with RA (13.2 %) and controls (13.2%, p = 0.017). The mean TBS of patients with PMR (1.317 ± 0.092) was significantly lower than those of patients with RA (1.336 ± 0.089) and the controls (1.373 ± 0.073, p0.001). In receiver operating characteristic analysis for VF in patients with PMR, the area under the curve (AUC) was 0.759 (95% confidence interval [CI] = 0.601-0.918, p0.001) for TBS and 0.618 (95% CI = 0.442-0.795, p0.001) for L-spine BMD. The AUCs were 0.760 (95% CI = 0.630-0.891, p ≤ 0.001) and 0.767 (95% CI 0.627-0.907, p0.001) for femur neck and total hip BMD, respectively. Multivariate analysis identified the factor associated with VF of patients with PMR as a lower TBS (Odds ratio: 0.000, 95% CI: 0.000, 0.754, p = 0.043).TBS could be a supplementary tool for discriminating osteoporotic fractures in postmenopausal patients with PMR.

Purpose TNF-α is a transmembrane protein which requires cleavage by ADAM17 in order to act systemically. The activation of ADAM17 to generate soluble TNF‑α results in an increased inflammatory activity. We hypothesized that variants spanning the ADAM17 gene contribute towards the observed variation in patient response defined by the number of changes in TNF‑α inhibitors. Patients and methods Seven single-nucleotide polymorphisms (SNPs) of ADAM17 in 63 patients with rheumatoid arthritis who received TNF-α inhibitors were analyzed: rs57467365, rs62117540, rs117645314, rs6432013, rs532704607, rs117179141, and rs12692386. Univariate and multivariate regression analysis were employed to investigate the independent predictable factors for changes in TNF-α inhibitors. Results ADAM17 rs117645314 and rs117179141 showed significant association with the number of changes in TNF-α inhibitors. Patients with GA in rs117645314 and AT in rs117179141 had significantly higher chance of two or more changes of TNF-α inhibitors than those with wild homozygous alleles. Multivariate analysis showed that rs117179141 explained 5.7% of the 23.8% variability in TNF-α inhibitor response. Conclusion This study showed that the number of changes in TNF-α inhibitor is associated with ADAM17 SNPs.

Neutrophils are innate immune phagocytes that play a key role in immune defense against invading pathogens. The main offensive mechanisms of neutrophils are the phagocytosis of pathogens, release of granules, and production of cytokines. The formation of neutrophil extracellular traps (NETs) has been described as a novel defense mechanism in the literature. NETs are a network of fibers assembled from chromatin deoxyribonucleic acid, histones, and neutrophil granule proteins that have the ability to kill pathogens, while they can also cause toxic effects in hosts. Activated neutrophils with NET formation stimulate autoimmune responses related to a wide range of inflammatory autoimmune diseases by exposing autoantigens in susceptible individuals. The association between increased NET formation and autoimmunity was first reported in antineutrophil cytoplasmic antibody-related vasculitis, and the role of NETs in various diseases, including systemic lupus erythematosus, rheumatoid arthritis, and psoriasis, has since been elucidated in research. Herein, we discuss the mechanistic role of neutrophils, including NETs, in the pathogenesis of systemic juvenile idiopathic arthritis (SJIA) and adult-onset Still’s disease (AOSD), and provide their clinical values as biomarkers for monitoring and prognosis.

This study investigated the role of Toll-like receptor 1 (TLR1), TLR2, TLR4, TLR7, and TLR9 in patients with adult-onset Still’s disease (AOSD). This study included 20 patients with AOSD and 15 healthy controls (HCs). TLR expression in the peripheral blood was quantified using flow cytometry; TLR expression pattern, in the skin lesions and lymph nodes (LNs) of patients with AOSD, was evaluated immunohistochemically. Significantly higher mean intensities of cells presenting TLR2 and TLR7 from whole blood were observed in patients with AOSD than in HCs. TLR2 expression in whole cells correlated with systemic scores, levels of lactate dehydrogenase and ferritin and serum levels of interleukin-1β (IL-1β), IL-6, and IL-18. The percentage of TLR2-positive inflammatory cells was higher in skin biopsy samples from patients with AOSD than those in HCs. TLR9-expressing positive inflammatory cell counts were higher in skin lesions from patients with AOSD than those in the HC, eczema, and psoriasis groups. The expression levels of TLR1, TLR4, TLR7, and TLR9 were higher in LNs of patients with AOSD than in those with T cell lymphoma and reactive lymphadenopathy. Circulating TLR2- and TLR7-positive cells may contribute to the pathogenesis of AOSD. Furthermore, immunohistochemical staining for TLRs in skin lesions and LNs may aid in differentiating AOSD from similar conditions.

Sjögren’s syndrome (SS) is a chronic autoimmune disease characterized by dry mouth and dry eyes, with lymphocytic infiltration of the exocrine glands. Saliva is becoming a useful tool to determine the clinical and pathological characteristics of SS because the collection method is easy and non-invasive. Since 1900, salivary proteomic analysis has been performed continuously using a variety of optimized analytical methods. Many studies have identified distinct characteristics of salivary proteins in patients with primary SS, and the changes were related to chronic inflammation and overproduction of immunoglobulins or downregulated secretory function. Several proteomic studies using whole or parotid saliva have evaluated whether several salivary proteins can be used to discriminate SS, including salivary β2-microglobulin, calprotectin, carbonic anhydrase VI, neutrophil gelatinase-associated lipocalin, sialic acid-binding immunoglobulin-like lectin-5, and tripartite motif-containing protein 29. In addition, salivary proinflammatory cytokine levels have been reported to be increased in patients with SS. Although these candidate salivary proteins have exhibited considerable differences in patients with SS, more data are needed to confirm their role as biomarkers. Moreover, the identification of salivary characteristics that can accurately reflect disease activity, predict treatment response and prognosis, and diagnose SS is anticipated.

This study was designed to investigate the effects of polymorphisms in RETN on remission in RA patients receiving TNF-α inhibitors. In addition, machine learning algorithms were trained to predict remission. Ten single-nucleotide polymorphisms were investigated. Univariate and multivariable analyses were performed to evaluate associations between genetic polymorphisms and the efficacy of TNF-α inhibitors. A random forest-based classification approach was used to assess the importance of different variables associated with the efficacy of TNF-α inhibitors. Various machine learning methods were used for finding vital factors and prediction of remission. The eight most significant features included in the multivariable analysis were sex, age, hypertension, sulfasalazine, rs1862513, rs3219178, rs3219177, and rs3745369. T-allele carriers of rs3219177 and males showed approximately 6.0- and 3.6-fold higher remission rates compared to those with the CC genotype and females, respectively. The elastic net algorithm was the best machine-learning method for predicting remission of patients with RA treated with TNF-α inhibitors. On the basis of the results of this study, it may be possible to design individually tailored treatment regimens to predict the efficacy of TNF-α inhibitors.

Unlike other biologic agents for rheumatoid arthritis (RA) that are administered at regular intervals even without flare, rituximab can be administered according to the timing of retreatment determined by the physician. Recently, there has been a tendency to prefer on-demand administration for disease flares rather than regular retreatment. We aimed to investigate the retreatment patterns of rituximab in patients with RA and to identify factors associated with extension of the time interval between retreatment courses. This study included RA patients on rituximab treatment who were enrolled in the Korean Rheumatology Biologics registry (KOBIO) or treated at Ajou University Hospital. Previous or current concomitant conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs), corticosteroids, number of previous biologic agents, withdrawal, and time intervals of rituximab retreatment were collected. In case of treatment failure, the reasons such as lack of efficacy, adverse events, and others, were also identified. A total of 82 patients were enrolled. The mean follow-up period from the first cycle of rituximab was 46.1 months, and the mean interval between the retreatment courses was 16.3 months. The persistent rates of rituximab after 5 years was 72.4%. Concomitant use of at least two csDMARDs (β = 4.672; 95% CI: 0.089–9.255, p = 0.046) and concomitant use of corticosteroids (β = 7.602; 95% CI: 0.924–14.28, p = 0.026) were independent factors for extending the time interval between the retreatment courses. In conclusion, RA patients treated with rituximab in Korea show high persistence rates. Concomitant use of two or more csDMARDs and concomitant use of corticosteroids with rituximab are associating factors of extending the retreatment time interval. These findings should be considered when selecting rituximab as a treatment for patients with RA.

Muscular dysfunction in rheumatoid arthritis (RA) can affect the quality of life and comorbidities. We enrolled 320 patients with RA, and evaluated their muscle mass, grip strength, and physical performance. Seven (2.2%) and 21 RA patients (6.6%) had sarcopenia, as defined by the European and Asian Working Group for Sarcopenia (EWGS and AWGS), respectively, 54 patients (16.9%) were determined to have low muscle mass with normal muscle function, as defined by the EWGS, 38 patients (11.9%) reported sarcopenia by SARC-F questionnaire. Male sex (odds ratio (OR) 140.65), low body mass index (BMI) (OR 0.41), and use of tumor necrosis factor (TNF) inhibitors (OR 4.84) were associated with a low muscle mass as defined by the EWGS, while male sex, old age, and low BMI were associated with sarcopenia as defined by the AWGS. Old age (OR 1.11), high BMI (OR 1.13), and a high Disease Activity Score 28 (OR 1.95) were associated with sarcopenia as reported on the SARC-F. Male, low BMI, and use of TNF inhibitors were associated with a low muscle mass, while male sex, old age, and low BMI were associated with sarcopenia in patients with long-standing RA.

The major salivary glands, namely, the parotid, submandibular, and sublingual glands, are important in maintaining oral cavity health. A salivary gland scan is used to evaluate the uptake and excretory function of the salivary glands. By intravenously injecting 99m TcO 4- , which is distributed like chloride ions in the body, the glands become visible on the salivary gland scan. The parotid and submandibular glands are typically appreciated on the salivary gland scan, but the sublingual gland is not. We present a rare image of a prominent sublingual gland on a salivary gland scan.

Infection occurs frequently in patients with systemic lupus erythematosus (SLE), and has been a major cause of morbidity and mortality. However, no large-scale comprehensive studies have estimated the effect of clinical characteristics on serious infection in actual clinical practice yet. We investigated the influence of clinical characteristics on serious infections using electronic medical records data. We conducted a nested case-control study. Patients with SLE who developed serious infection which needs hospitalization or intravenous antibiotics (n = 120) were matched to controls (n = 240) who didn’t. Odds ratios (OR) and 95% confidence intervals (CIs) for infection associated with clinical features were obtained by conditional logistic regression analyses. The conditional logistic regression analysis with adjustment showed that serositis (OR, 2.76; 95% CI, 1.33–5.74), hematologic involvement (OR, 2.53; 95% CI, 1.32–4.87), and use of higher than the low dose of glucocorticoids (GCs; >7.5 mg/d prednisolone-equivalent) (OR, 2.65; 95% CI, 1.31–5.34) were related to serious infections in SLE. Serositis, hematologic involvement, and use of higher than the low dose of GCs were associated with serious infections in patients with SLE.

Relatively little is known about what motivates or prevents patients with rheumatoid arthritis (RA) from adopting physically active lifestyles. This study aimed to evaluate the levels of physical activity and to identify the factors affecting a physically active lifestyle among Korean patients with RA. In this cross-sectional study, data were collected from a rheumatology outpatient clinic of a university-affiliated hospital in South Korea. The levels of physical activity were self-reported using the International Physical Activity Questionnaire. Participants who engaged in more than 600 metabolic equivalent task-minutes/week of physical activity and moderate activity or walking at least three times per week were considered physically active in this study. Structured questionnaires were used to assess perceived barriers and self-efficacy for exercise. Of 345 patients with RA included in this study, about 22% of patients were classified as physically active. Factors associated with a physically active lifestyle were good physical function (odds ratio [OR] = 0.56; 95% confidence interval [CI]: 0.36-0.87) and high levels of exercise self-efficacy (OR = 1.36; 95% CI: 1.20-1.54). Common barriers identified were fatigue, interference with other responsibilities, and a lack of time. Participants showed the lowest self-efficacy for exercise when they had pain and were busy with other activities. The level of physical function and exercise self-efficacy were predictors of physical activity. Individualized physical activity programs tailored to personal abilities and barriers and increasing exercise self-efficacy are needed to facilitate engagement of physical activity in Korean patients with RA. KEY POINTS: • Factors associated with a physically active lifestyle were good physical function and high levels of exercise self-efficacy. • The levels of exercise self-efficacy in Korean patients with RA are low compared to those in other populations. • Frequently encountered barriers in the subjects were being too tired, interference with other responsibilities, and lack of time. • Individualized physical activity programs tailored to personal abilities and barriers and increasing exercise self-efficacy are needed to facilitate engagement of physical activity in Korean patients with RA.

A defect in clearance of apoptotic materials is pivotal in the pathogenesis of systemic lupus erythematosus (SLE). Protein S participates in the removal of apoptotic remnants and the anticoagulation pathway. The aim of the study was to clarify the relationship between plasma levels of free protein S and the disease activity or subclinical atherosclerosis in SLE. Free protein S was measured by an enzyme-linked immunosorbent assay, and patients were classified into two groups of free protein S levels: low (50%) and normal (≥ 50%). One hundred-eleven Korean female patients with SLE were enrolled, and the levels of free protein S were 67.4 ± 19.7%. Carotid plaque was detected in 25 (22.5%) patients. Twenty-one patients with low free protein S had lower hemoglobin (11.4 ± 1.4 vs. 12.5 ± 1.4 g/dL) and lymphocytes (1,221 ± 609 vs. 1,720 ± 1,097/µL), higher erythrocyte sedimentation rate (30.1 ± 20.6 vs. 20.8 ± 17.8 mm/h), and lower complement 3 (80.8 ± 27.6 vs. 103.4 ± 25.8 mg/dL) and complement 4 (15.6 ± 10.4 vs. 21.5 ± 7.6 mg/dL) than those with normal protein S. There was no significant difference in the proportion of patients with increased carotid artery intima-media thickness (4.6 mm) or with carotid artery plaque between two groups. The low levels of free protein S were associated with hemoglobin (OR = 0.64, p = 0.04) and complement 3 (OR = 0.96, p = 0.005). Free protein S is correlated with disease activity, but not with subclinical atherosclerosis in SLE.