Childhood-Onset Systemic Lupus Erythematosus: Southeast Asian Perspectives

Utility of pan-immune-inflammation value as a predictor of the prognosis of childhood lupus

BACKGROUND

Systemic lupus erythematosus (SLE) is a chronic inflammatory multisystemic disease. Monitoring disease activity thoughtout the disease course is important for effective management and assessment of disease outcome.

OBJECTIVE

To assess whether the pan-immune inflammation value (PIIV) at diagnosis could predict organ involvement and disease activity in childhood SLE (cSLE) patients after 12 months of disease onst.

METHODS

This is an observational retrospective multicenter study that comprised cSLE patients seen and followed at the participating centers between January 2010 and December 2022. All patients met the EULAR/ACR-19 criteria, were immunosuppressive drug-naïve at the time of SLE diagnosis and had a minimal follow-up period of 12 months. The data included clinical and laboratory findings and disease activity using the SLEDAI-2K. Receiver operating characteristic (ROC) curves were employed to determine the optimal cut-off value of PIIV and assess its predictive potential for disease activity, and organ involvement.

RESULTS

A total of 125 patients (104 female) with a median age of 16.0 (IQR 5.6) years, a median age at disease onset of 10.9 (IQR 3.0) years, and a median disease duration of 4.8 (IQR 5.3) years were included. The most frequent involved organs at diagnosis were hematological (89.6%), musculoskeletal (68.8%), mucocutaneous (63.2%), and renal (58.4%). However, at a 12-month follow-up visit, the most frequent involved organs were renal (40.0%), hematological (39.2%), musculoskeletal (15.2%), and mucocutaneous (10.4%). The median PIIV at diagnosis was 139 (IQR 229.6), while the median SLEDAI was 12 (IQR 6.5) and 3.5 (IQR 7.0) at diagnosis and 12 months, respectively. An optimal PIIV cut-off of 250 was found to be a predicative for disease activity, with a sensitivity of 45% and a specificity of 86%. The study revealed that the PIIV successfully predicted four systems in our cohort of patients.

CONCLUSION

Our work suggests the PIIV might be a reasonable predictor for organ involvement and disease activity in newly diagnosed cSLE, though further research, particularly larger studies, is required to validate these findings, especially regarding organ involvement.

Childhood-Onset Systemic Lupus Erythematosus (cSLE): An International Perspective

PURPOSE OF REVIEW

Childhood-onset systemic lupus erythematosus (cSLE) is a severe and potentially life-threatening chronic autoimmune disease. cSLE is more aggressive and has poorer outcomes than adult-onset disease. The global burden of cSLE is poorly understood, with most publications on cSLE originating from high-resourced settings. The reports from less resourced settings indicate high morbidity and mortality in these populations.

RECENT FINDINGS

In this article, we review the disparities in global access to rheumatology care and research for patients with cSLE. We highlight recent cSLE advances from all regions of the globe. We describe current obstacles to cSLE clinical care and research in all settings. Finally, we propose a path forward for high quality, equitable and accessible care to individuals with cSLE everywhere. Individuals with cSLE are at risk for morbidity and death, yet patients worldwide face challenges to adequate access to care and research. Sustained, collaborative efforts are needed to create pathways to improve care and outcomes for these patients.

Mortality and prognostic factors among inpatients with systemic lupus erythematosus in China: A 20-year retrospective study

OBJECTIVE

To summarize the causes of death and clinical characteristics of systemic lupus erythematosus (SLE) hospitalized patients in the last 20 years to improve SLE survival rates by detecting critical SLE early.

METHODS

In this case-control study, 218 SLE death cases were retrospectively analyzed from January 2002 to December 2022, with 110 SLE inpatients chosen at random as controls. The clinical symptoms, causes of death, and risk factors in patients with SLE were investigated.

RESULTS

There were 218 deaths among 9538 patients with SLE, including 188 women and 30 men. The death rate fell steadily from 4.14% in 2002 to 1.96% in 2013 and remained at 1.84% from 2014 to 2022. The standardized mortality ratio (SMR) was 4.98 [95% CI (4.06-5.89)] from 2002 to 2012 and 3.39 [95% CI (2.74-4.04)] from 2013 to 2022. Infection, lupus-induced multiple organ failure syndrome (MODS), and neuropsychiatric lupus (NPLE) were the leading causes of death, accounting for 31.19%, 15.14%, and 11.47% of overall deaths. Age had a significant association with the major causes of death. Logistic regression analysis showed NPLE[OR = 10.772,95% CI (3.350,34.633), p < 0.001], lupus pulmonary involvement (LP)[OR = 3.844,95%CI (1.547,9.552), p = 0.004], pneumonia[OR = 3.439,95%CI(1.552,7.621), p = 0.002], thrombocytopenia[OR = 14.941,95%CI (4.088,54.604), p < 0.001], creatinine>177 μmol/L[OR = 8.644,95%CI (2.831,26.388), p < 0.001], glutamic transaminase(AST) > 60U/L[OR = 5.762,95%CI (2.200,15.088), p < 0.001], total bilirubin > 34 μmol/L[OR = 16.701,95%CI (3.349,83.294), p = 0.001], higher SLE Disease Activity Index (SLEDAI)[OR = 1.089,95%CI (1.032,1.149), p = 0.002] and SLE Damage Index (SDI)[OR = 3.690,95%CI (2.487,5.474), p < 0.001] correlated positively with death.

CONCLUSION

From 2002 to 2013, the mortality rate among patients with SLE fell steadily but remained unchanged from 2014 to 2022. Patients with SLE had significantly higher SMR than the general population. Childhood-onset SLE had a poorer prognosis than adult-onset SLE. Infection, MODS, and NPLE were the three leading causes of death. Major organ involvement and high disease activity were risk factors for mortality.

Diagnostic performance of classification criteria for systemic lupus erythematosus: A validation study from Singapore

Introduction

Classification criteria for systemic lupus erythematosus (SLE) include American College of Rheumatology (ACR) 1997, Systemic Lupus Erythematosus International Collaborating Clinics (SLICC) 2012 and European Alliance of Associations for Rheumatology (EULAR)/ACR 2019 criteria. Their performance in an Asian childhood-onset SLE (cSLE) population remains unclear as the clinical manifestations differ. We aim to evaluate the diagnostic performance in a cSLE cohort in Singapore.

Method

Cases were physician-diagnosed cSLE, while controls were children with mixed and undifferentiated connective tissue disease that posed an initial diagnostic challenge. Data were retrospec-tively reviewed to establish the 3 criteria fulfilled at diagnosis and over time.

Results

The study population included 120 cSLE cases and 36 controls. At diagnosis, 102 (85%) patients fulfilled all criteria. SLICC-2012 had the highest sensitivity (97.5%, 95% confidence interval [CI] 92.3-99.5), while ACR-1997 had the highest specificity (91.7%, 95% CI 77.5-98.3). All criteria had diagnostic accuracies at more than 85%. Over time, 113 (94%) fulfilled all criteria. SLICC-2012 remained the criteria with the highest sensitivity (99.2%, 95% CI 95.4-99.9), while ACR-1997 had the highest specificity (75.0%, 95% CI 57.8-87.9). Only SLICC-2012 and ACR-1997 had more than 85% diagnostic accuracy over time. Using a cutoff score of ≥13 for EULAR/ACR-2019 criteria resulted in improved diagnostic performance.

Conclusion

SLICC-2012 criteria had the highest sensitivity early in the disease course in this first study evaluating the SLE classification criteria performance in a Southeast Asian cSLE cohort, while the ACR-1997 criteria had the highest specificity. Using a cutoff score of ≥13 for EULAR/ACR-2019 improved the diagnostic performance.

Decrease of left ventricular function measured by speckle-tracking echocardiography based on systemic lupus erythematosus severity in children

INTRODUCTION

Systemic lupus erythematosus in children generally manifests more severely with a more aggressive disease course. Cardiac involvement in systemic lupus erythematosus often does not show specific signs and symptoms, but speckle-tracking echocardiography can detect cardiac dysfunction. This study aimed to determine the differences in left ventricular function as measured by speckle-tracking echocardiography in children with various severity of systemic lupus erythematosus activity.

METHODS

A cross-sectional study of 49 children diagnosed with systemic lupus erythematosus are currently undergoing outpatient or inpatient care at Dr Hasan Sadikin General Hospital, Bandung, from May 2023 to June 2023. Disease activity was assessed by Mexican Version of the Systemic Lupus Erythematosus Disease Activity Index (MEX-SLEDAI) with a score of 2-5 classified as mild activity, 6-9 as moderate, and ≥10 as severe. Each subject underwent conventional echocardiography and speckle-tracking echocardiography with a Philips EPIQ machine performed by a Pediatric Cardiologist Consultant 10 days after inclusion.

RESULTS

Fifteen (30.6%) subjects had mild disease activity, and 34 (69.4%) subjects had moderate disease activity. Most subjects (81.96%) were female with an average age of 15 years. The mean ejection fraction and fractional shortening as well as the median E/A ratio in the mild and moderate disease activity groups were not significantly different (65.76 versus 67.38%, 35.73 versus 37.11%, 1.6 versus 1.5%, respectively, p > 0.005). The global longitudinal strain in the moderate activity group was reduced more significantly than in the mild activity group (-16.58 versus -19.65, p = 0.008).

CONCLUSION

Left ventricular function as measured by speckle-tracking echocardiography was lower in children with moderate systemic lupus erythematosus activity than those with mild disease activity.

Childhood-Onset Systemic Lupus Erythematosus Presenting With Concomitant Gastrointestinal Manifestation and Antiphospholipid Syndrome

Childhood-onset systemic lupus erythematosus is a rare disease that is more prevalent in Southeast Asian children than in Western children. It is characterised by a peripubertal onset and a female predominance that rises with age. Haematological, renal, and mucocutaneous are among the frequently involved organs upon diagnosis. Some of the typical symptoms include cutaneous vasculitis, malar rash, and fever. Patients frequently had proliferative class IV lupus nephritis, which increases disease activity and kidney damage. We reported a child presented with fever associated with multiple joint pain, skin rashes over the fingers of the right hand, and generalised abdominal pain.

An eight-year old girl with fever and rash: What is the possible diagnosis?

In this clinical challenge, we describe the case of a previously healthy 8-year-old girl who presented to a primary care clinic with fever, reduced oral intake and malaise on day 3 of her illness. Clinical examination revealed that she was tachypnoeic and tachycardic. An erythematous rash was found across the bridge of her nose and cheeks, and several painless ulcers were noted in the oral cavity. Blood investigation showed thrombocytopenia, while urinalysis revealed microscopic haematuria and proteinuria. Useful initial diagnostic imaging studies were discussed, including bedside ultrasound in the ambulatory care setting. It is imperative that primary care providers be vigilant when encountering cases like this.

Case report: Aseptic splenic abscesses in childhood-onset systemic lupus erythematosus

Background

Systemic lupus erythematosus (SLE) can involve any organ system and cause a wide range of manifestations. Noninfectious inflammatory lesions termed aseptic abscesses have been reported in some autoimmune and autoinflammatory conditions but not in childhood-onset SLE. In this report, we highlight the unusual finding of occult splenic abscesses in two children diagnosed with SLE who had no evidence of concomitant infection.

Case presentation

An 8-year-old and an 11-year-old were admitted separately to the hospital with fever for 7 and 14 days, respectively. In the younger child, a generalized rash preceded the fever. Both had been well, with no significant past medical history prior to the onset of the illness. In both girls, abdominal ultrasonography showed multiple small hypoechoic lesions suggestive of abscesses scattered throughout the spleen. Their C-reactive protein and blood cultures were negative, and symptoms persisted despite intravenous antibiotics. Fulfilling the clinical and immunologic criteria for diagnosis, both were ultimately diagnosed with childhood-onset SLE. Rapid recovery of symptoms and complete resolution of the abscesses ensued with corticosteroids and immunosuppressive therapy.

Conclusions

These two cases suggest that aseptic splenic abscesses may occur in childhood-onset SLE. Autoimmune conditions such as SLE should be included in the differential diagnosis of children with occult splenic abscesses.

Management and outcomes in children with lupus nephritis in the developing countries

BACKGROUND

Lupus nephritis (LN) has variable prevalence, severity, and outcomes across the world.

OBJECTIVES

This review compares the outcomes of childhood LN in low- and middle-income countries (LMICs) and high-income countries (HICs) and aims to summarize long-term outcomes of pediatric LN from LMICs.

DATA SOURCES

A systematic literature search, conducted in PubMed, EMBASE, and Cochrane database in the last 30-years from January 1992, published in the English language, identified 113 studies including 52 from lower (n = 1336) and upper MICs (n = 3014).

STUDY ELIGIBILITY CRITERIA

Cohort studies or randomized controlled trials, of patients ≤ 18 years of age (or where such data can be separately extracted), with > 10 patients with clinically or histologically diagnosed LN and outcomes reported beyond 12 months were included.

PARTICIPANTS AND INTERVENTIONS

Patients ≤ 18 years of age with clinically or histologically diagnosed LN; effect of an intervention was not measured.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two authors independently extracted data. We separately analyzed studies from developed countries (high income countries; HIC) and developing countries (LMICs). Middle-income countries were further classified as lower and upper MICs. Meta-analyses of data were performed by calculating a pooled estimate utilizing the random-effects model. Test for heterogeneity was applied using I² statistics. Publication bias was assessed using funnel plots.

RESULTS

Kidney remission was similar across MICs and HICs with 1-year pooled complete remission rates of 59% (95% CI 51-67%); one third of patients had kidney flares. The pooled 5-year survival free of stage 5 chronic kidney disease (CKD5) was lower in MICs, especially in lower MICs compared to HICs (83% vs. 93%; P = 0.002). The pooled 5-year patient survival was significantly lower in MICs than HICs (85% vs. 94%; P < 0.001). In patients with class IV LN, the 5-and 10-year respective risk of CKD5 was 14% and 30% in MICs; corresponding risks in HICs were 8% and 17%. Long-term data from developing countries was limited. Sepsis (48.8%), kidney failure (14%), lupus activity (18.1%), and intracranial hemorrhage/infarct (5.4%) were chief causes of death; mortality due to complications of kidney failure was more common in lower MICs (25.6%) than HICs (6.4%).

LIMITATIONS

The review is limited by heterogenous approach to diagnosis and management that has changed over the period spanning the review. World Bank classification based on income might not correlate with the standards of medical care. The overall quality of evidence is low since included studies were chiefly retrospective and single center.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Challenges in LMICs include limited access to pediatric nephrology care, dialysis, increased risk of infection-induced mortality, lack of frequent monitoring, and non-compliance due to cost of therapy. Attention to these issues might update the existing data and improve patient follow-up and outcomes.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO 2022 number: CRD42022359002, available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022359002.

A Preliminary Predictive Model for Proliferative Lupus Nephritis in Juvenile Systemic Lupus Erythematosus

Proliferative lupus nephritis, which is diagnosed by renal biopsy, has significant impact on the treatment choices and long-term prognosis of juvenile SLE (jSLE). Renal biopsies are however not always possible or available, thus leading to an ongoing search for alternative biomarkers. This study aimed to develop a clinical predictive machine learning model using routine standard parameters as an alternative tool to evaluate the probability of proliferative lupus nephritis (ISN/RPS Class III or IV). Data were collected retrospectively from jSLE patients seen at Selayang Hospital from 2004 to 2021. A total of 22 variables including demographic, clinical and laboratory features were analyzed. A recursive feature elimination technique was used to identify factors to predict pediatric proliferative lupus nephritis. Various models were then used to build predictive machine learning models and assessed for sensitivity, specificity and accuracy. There were 194 jSLE patients (165 females), of which 111 had lupus nephritis (54 proliferative pattern). A combination of 11 variables consisting of gender, ethnicity, fever, nephrotic state, hypertension, urine red blood cells (RBC), C3, C4, duration of illness, serum albumin, and proteinuria demonstrated the highest accuracy of 79.4% in predicting proliferative lupus nephritis. A decision-tree model performed the best with an AROC of 69.9%, accuracy of 73.85%, sensitivity of 78.72% and specificity of 61.11%. A potential clinically useful predictive model using a combination of 11 non-invasive variables to collectively predict pediatric proliferative lupus nephritis in daily practice was developed.

The pathological spectrum of pediatric kidney disease: 18-Year experience from a single tertiary care center in northern Taiwan

BACKGROUND

Glomerular disease is one of the leading causes of chronic kidney disease in children worldwide. Recent studies outlined the changing spectrum of glomerular disease in certain countries. Therefore, our study aimed to evaluate the histopathological patterns and changes in pediatric kidney disease over the past 18 years in northern Taiwan.

METHODS

This was a retrospective chart review study of pediatric patients (≤18 years of age) undergoing percutaneous renal biopsies (PRBs) of native kidneys between January 2002 and July 2020 from a Pediatric Care Center at Chang Gung Memorial Hospital, Taoyuan, Taiwan.

RESULTS

This study analyzed a total of 339 pediatric native PRBs. The mean age of the subjects was 13.7 ± 7.0 years (184 girls and 155 boys). The most common indications of PRBs included acute nephritic syndrome (55.7%), idiopathic nephrotic syndrome (22.7%), persistent asymptomatic hematuria (13.9%), and unexplained renal failure (7.7%). Our study revealed that proliferative lupus nephritis (LN), minimal change disease (MCD)-related nephrotic syndrome, and IgA nephropathy (IgAN) were the most frequent biopsy-proven pediatric glomerular diseases. In addition, we showed that severe acute post-streptococcal glomerulonephritis (APSGN) was infrequent and has not even been diagnosed since 2010.

CONCLUSION

Our result revealed that the spectrum of biopsy-proven pediatric kidney disease has not changed significantly over the past two decades. Furthermore, proliferative LN, MCD, and primary IgAN continue to be the most common histopathological diagnoses among Taiwanese children.

Clinical and histopathological study of renal biopsy in Nepalese children: A single center experience

BACKGROUND

Glomerular diseases are important causes of morbidity and mortality among children in developing countries. Renal biopsy is the gold standard for determining histological diagnosis, prognosis, and therapy options. This study aimed to investigate the clinical, histopathological, and direct immunofluorescence findings of renal biopsy results in Nepalese children under 18 years old.

METHODS

In this retrospective cross-sectional study, the available data from children who had undergone kidney biopsy between 2016 and the end of 2020 were evaluated. Demographic data, indications of biopsy, histopathologic findings, and direct immunofluorescence findings were collected and presented.

RESULTS

The mean age of the patients was 12.14 ± 4.07 years. Male/female ratio was 1:1. The majority of biopsy cases were aged between 11-15 years of age. The most common indication for biopsy in children was nephrotic syndrome (68.25%). Lupus nephritis with 28 cases (22.22%) had the highest frequency in overall renal biopsies. Minimal change disease (MCD) with 22 cases (17.46%) followed by Ig A nephropathy with 16 cases (12.69%) were the most frequent primary glomerulonephritis. Lupus nephritis showed full house positivity, and MCD showed full house negativity in all Direct immunofluorescence (DIF) parameters, whereas immunoglobulin A nephropathy showed 100% positivity in Ig A in DIF.

CONCLUSIONS

Nephrotic syndrome was the most common indication for renal biopsy. The most common primary glomerulonephritis was MCD, while secondary glomerulonephritis was lupus nephritis. Clinical data, light microscopy, and direct DIF played an integral role in the overall final diagnosis.

Expression of the miR-9-5p, miR-125b-5p and its target gene NFKB1 and TRAF6 in childhood-onset systemic lupus erythematosus (cSLE)

Childhood- onset systemic lupus erythematosus (cSLE) is a multisystem inflammatory disease that can lead to severe clinical conditions resulting in early comorbidities. Several genetic, environmental, and immunological factors are known to influence the onset of the disease. MiRNAs have been already considered as potential actors involved in the development and activity of the SLE. Thus, understanding the behavior of these regulators can contribute to clarify the inflammatory process affecting SLE patients. Among miRNAs, miR-125b-5p and miR-9-5p targeting NFKB1 and TRAF6 genes can be involved in the etio-pathogenesis of the disease by modulating inflammation. In this study we evaluated miR-9-5p and miR-125b-5p expression and its target genes NFKB1 and TRAF6 in peripheral blood samples (PBMC) from the 35 cSLE patients and 35 healthy controls. MiRNAs and gene target expression have been evaluated by using RT-PCR with specific TaqMan® probes. Both miR-9-5p [Fold Change (FC) = -2.21; p = 0.002] and miR-125b-5p (FC= -3.30; p < 0.0001) and NFKB1 (FC = -1.84; p < 0.001) were downregulated in cSLE patients, while TRAF6 was upregulated (FC = 1.80; p = 0.006) in cSLE patients when compared to controls. A significant correlation was found between miR-125b-5p and its target gene NFKB1 [Spearman (r) = 0.47; p = 0.023]. Our results showed miR-125b-5p and miR-9-5p differential expression in cSLE patients, possibly contributing to better understanding the role of these regulators in cSLE development and disease pathogenesis.

Sex and gender differences in chronic kidney disease and access to care around the globe

The difference between sex, the biological construct, and gender, the social construct, may be most evident in settings of vulnerability. Globally, chronic kidney disease is more prevalent among women, but the prevalence of end-stage kidney failure, and especially receipt of kidney replacement therapy, is higher in men. These differences likely reflect a combination of physiological and social/structural risk factors that independently modulate kidney disease and/or its progression. The distribution of the most common risk factors such as hypertension and obesity differ between men and women and may impact disease risk differentially. Social and structural gender-related inequities remain stark across the globe. More women live in poverty, receive less education, and are more dependent on others for health care decision making, but men may have a higher risk of injury, occupational exposures, and less access to screening, prevention, and primary care. In this article, we explore how social determinants of health affect kidney disease risk and access to care differentially across genders, and differently across the globe. We also describe specific challenges experienced by boys and girls with kidney disease, how culture and geography may impact kidney care in places where resources are particularly limited such as sub-Saharan Africa, and give examples of social and structural circumstances that place young men and women at high risk of kidney disease in Mexico and Central America, illustrated by case vignettes. The coronavirus disease-2019 pandemic has raised awareness of pervasive gender-based inequities within all societies. This applies to kidney disease and is not new. The nephrology community must add its voice to the calls for action, for a more just society overall, and for the recognition of the roles of sex and gender as modulators of kidney disease risk and access to care.

Systemic lupus erythematosus children in Egypt: Homeland spectrum amid the global situation

OBJECTIVES

This study aims to present the manifestations of juvenile systemic lupus erythematosus (JSLE) across Egypt, to focus on age at onset and gender-driven influence on disease characteristics, and to compare findings to other countries.

METHODS

The study included 404 Egyptian children with systemic lupus erythematosus (SLE) presenting to one of the specialized rheumatology centers corresponding to 13 major governorates. Juvenile cases age was ≤ 16°years at the time of recruitment. The SLE Disease Activity Index (SLEDAI) and damage index (DI) were assessed.

RESULTS

The mean age was 13.2 ± 2.4°years; 355 females and 49 males (7.2:1), and the disease duration was 2.3 ± 1.6 years, while age at disease onset was 11.1 ± 2.5°years. Their SLEDAI was 13.5 ± 12.3, and DI, 0.36 ± 0.78. The overall estimated prevalence of childhood-SLE patients in the recruited cohort in Egypt was 1/100,000 population (0.24/100000 males and 1.8/100000 females). 7.4% developed pre-pubertal SLE (≤ 7 years); 73.3%, peri-pubertal; and 19.3% during early adolescence. The differences according to age group were equal for gender and clinical manifestations except skin lesions present in 59.3% of pre-pubertal onset, 74.6% of peri-pubertal, and 84.2% of adolescents (p = 0.029), and renal involvement in 73.8% of peripubertal, 62.1% of pre-pubertal and 58.9% of adolescents (p = 0.03). Laboratory investigations, SLEDAI, and DI were similar among age categories. Lupus nephritis was more common in Egypt compared to JSLE from other countries.

CONCLUSION

Our large multicenter study identified that female gender influenced disease characteristics with more frequent skin involvement. Skin lesions were significantly higher in adolescents, while renal involvement in peri-pubertal children.

Mycophenolic Acid Exposure Optimization Based on Vitamin D Status in Children with Systemic Lupus Erythematosus: A Single-Center Retrospective Study

Introduction

Systemic lupus erythematosus (SLE) can affect bone metabolism and homeostasis of serum electrolytes that are associated with abnormal levels of vitamin D. Mycophenolate mofetil (MMF) is a commonly used immunosuppressant with the active metabolite mycophenolic acid (MPA). The area under the plasma concentration–time curve (AUC) of MPA is often monitored during the treatment to assess the exposure levels. This study aims to explore the association between exposure levels of MPA and 25-hydroxyvitamin D [25(OH)D] levels in children with SLE.

Methods

Repeated measured data of children with SLE who were treated with MMF and under therapeutic drug monitoring (TDM) were retrospectively collected from the electronic medical records. MPA exposure levels were reflected by the area under the concentration–time curve over 24 h (AUC_0–24h). Univariate and multivariate linear regression models were employed to analyze factors associated with 25(OH)D levels. Hierarchical linear models were developed to analyze the intra- and inter-individual effects of AUC_0–24h on the variance of 25(OH)D levels.

Results

Data from 184 children with SLE (142 female and 42 male) with 518 follow-ups were collected. The median age was 14 years (range 3–18 years) at TDM. Children with normal 25(OH)D levels had significantly higher AUC_0–24h than children with low 25(OH)D levels (98.71 vs. 84.05 mg·h/L, P = 0.004). Intra- and inter-individual effects of AUC_0–24h on 25(OH)D levels were similar (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\gamma }_{10}$$\end{document}γ10 = 0.034 vs. \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\gamma }_{01}$$\end{document}γ01 = 0.037) but only the intra-individual effect was significant (P = 0.001) in hierarchical models. Other associated factors include age, sex, season at measurement, glucocorticoid daily dose, and external vitamin D₃ supplements.

Conclusion

25(OH)D levels are associated with MPA exposure levels, and may serve as a potential indicator to optimize the exposure level of MPA during treatment. AUC_0–24h of 98.71 mg·h/L or AUC_0–12h of 49.36 mg·h/L could be the targeted exposure level for children with SLE.