Associations of clinical and inflammatory biomarker clusters with juvenile idiopathic arthritis categories.

OBJECTIVE: To identify discrete clusters comprising clinical features and inflammatory biomarkers in children with JIA and to determine cluster alignment with JIA categories. METHODS: A Canadian prospective inception cohort comprising 150 children with JIA was evaluated at baseline (visit 1) and after six months (visit 2). Data included clinical manifestations and inflammation-related biomarkers. Probabilistic principal component analysis identified sets of composite variables, or principal components, from 191 original variables. To discern new clinical-biomarker clusters (clusters), Gaussian mixture models were fit to the data. Newly-defined clusters and JIA categories were compared. Agreement between the two was assessed using Kruskal-Wallis analyses and contingency plots. RESULTS: Three principal components recovered 35% (three clusters) and 40% (five clusters) of the variance in patient profiles in visits 1 and 2, respectively. None of the clusters aligned precisely with any of the seven JIA categories but rather spanned multiple categories. Results demonstrated that the newly defined clinical-biomarker lustres are more homogeneous than JIA categories. CONCLUSION: Applying unsupervised data mining to clinical and inflammatory biomarker data discerns discrete clusters that intersect multiple JIA categories. Results suggest that certain groups of patients within different JIA categories are more aligned pathobiologically than their separate clinical categorizations suggest. Applying data mining analyses to complex datasets can generate insights into JIA pathogenesis and could contribute to biologically based refinements in JIA classification.

Clinical and associated inflammatory biomarker features predictive of short-term outcomes in non-systemic juvenile idiopathic arthritis.

OBJECTIVE: To identify early predictors of disease activity at 18 months in JIA using clinical and biomarker profiling. METHODS: Clinical and biomarker data were collected at JIA diagnosis in a prospective longitudinal inception cohort of 82 children with non-systemic JIA, and their ability to predict an active joint count of 0, a physician global assessment of disease activity of ≤1 cm, and inactive disease by Wallace 2004 criteria 18 months later was assessed. Correlation-based feature selection and ReliefF were used to shortlist predictors and random forest models were trained to predict outcomes. RESULTS: From the original 112 features, 13 effectively predicted 18-month outcomes. They included age, number of active/effused joints, wrist, ankle and/or knee involvement, ESR, ANA positivity and plasma levels of five inflammatory biomarkers (IL-10, IL-17, IL-12p70, soluble low-density lipoprotein receptor-related protein 1 and vitamin D), at enrolment. The clinical plus biomarker panel predicted active joint count = 0, physician global assessment ≤ 1, and inactive disease after 18 months with 0.79, 0.80 and 0.83 accuracy and 0.84, 0.83, 0.88 area under the curve, respectively. Using clinical features alone resulted in 0.75, 0.72 and 0.80 accuracy, and area under the curve values of 0.81, 0.78 and 0.83, respectively. CONCLUSION: A panel of five plasma biomarkers combined with clinical features at the time of diagnosis more accurately predicted short-term disease activity in JIA than clinical characteristics alone. If validated in external cohorts, such a panel may guide more rationally conceived, biologically based, personalized treatment strategies in early JIA.

Higher concentrations of vitamin D in Canadian children with juvenile idiopathic arthritis compared to healthy controls are associated with more frequent use of vitamin D supplements and season of birth.

A number of studies have demonstrated that patients with autoimmune disease have lower levels of vitamin D prompting speculation that vitamin D might suppress inflammation and immune responses in children with juvenile idiopathic arthritis (JIA).  The objective of this study was to compare vitamin D levels in children with JIA at disease onset with healthy children. We hypothesized that children and adolescents with JIA have lower vitamin D levels than healthy children and adolescents. Data from a Canadian cohort of children with new-onset JIA (n= 164, data collection 2007-2012) were compared to Canadian Health Measures Survey (CHMS) data (n=4027, data collection 2007-2011). We compared 25-hydroxy vitamin D (25(OH)D) concentrations with measures of inflammation, vitamin D supplement use, milk intake, and season of birth. Mean 25(OH)D level was significantly higher in patients with JIA (79 ± 3.1 nmol/L) than in healthy controls (68 ± 1.8 nmol/L P <.05). Patients with JIA more often used vitamin D containing supplements (50% vs. 7%; P <.05). The prevalence of 25(OH)D deficiency (<30 nmol/L) was 6% for both groups. Children with JIA with 25(OH)D deficiency or insufficiency (<50 nmol/L) had higher C-reactive protein levels. Children with JIA were more often born in the fall and winter compared to healthy children. In contrast to earlier studies, we found vitamin D levels in Canadian children with JIA were higher compared to healthy children and associated with more frequent use of vitamin D supplements. Among children with JIA, low vitamin D levels were associated with indicators of greater inflammation.

Soluble Low-density Lipoprotein Receptor-related Protein 1 in Juvenile Idiopathic Arthritis.

OBJECTIVES: This study aimed to expand knowledge about soluble low-density lipoprotein receptor-related protein 1 (sLRP1) in juvenile idiopathic arthritis (JIA) by determining associations of sLRP1 levels in nonsystemic JIA patients with clinical and inflammatory biomarker indicators of disease activity. METHODS: Plasma sLRP1 and 44 inflammation-related biomarkers were measured at enrollment and 6 months later in a cohort of 96 newly diagnosed Canadian patients with nonsystemic JIA. Relationships between sLRP1 levels and indicators of disease activity and biomarker levels were analyzed at both visits. RESULTS: At enrollment, sLRP1 levels correlated negatively with age and active joint counts. Children showed significantly higher levels of sLRP1 than adolescents (mean ranks: 55.4 and 41.9, respectively; P = 0.02). Participants with 4 or fewer active joints, compared to those with 5 or more active joints, had significantly higher sLRP1 levels (mean ranks: 56.2 and 40.7, respectively; P = 0.006). At enrollment, considering the entire cohort, sLRP1 correlated negatively with the number of active joints (r = -0.235, P = 0.017). In the entire cohort, sLRP1 levels at enrollment and 6 months later correlated with 13 and 6 pro- and antiinflammatory biomarkers, respectively. In JIA categories, sLRP1 correlations with inflammatory markers were significant in rheumatoid factor-negative polyarticular JIA, oligoarticular JIA, enthesitis-related arthritis, and psoriatic arthritis at enrollment. Higher sLRP1 levels at enrollment increased the likelihood of absence of active joints 6 months later. CONCLUSION: Plasma sLRP1 levels correlate with clinical and biomarker indicators of short-term improvement in JIA disease activity, supporting sLRP1 as an upstream biomarker of potential utility for assessing JIA disease activity and outcome prediction.

Clinical and psychosocial stress factors are associated with decline in physical activity over time in children with juvenile idiopathic arthritis.

BACKGROUND: Physical activity (PA) patterns in children with juvenile idiopathic arthritis (JIA) over time are not well described. The aim of this study was to describe associations of physical activity (PA) with disease activity, function, pain, and psychosocial stress in the 2 years following diagnosis in an inception cohort of children with juvenile idiopathic arthritis (JIA). METHODS: In 82 children with newly diagnosed JIA, PA levels, prospectively determined at enrollment, 12 and 24 months using the Physical Activity Questionnaire for Children (PAQ-C) and Adolescents (PAQ-A) raw scores, were evaluated in relation to disease activity as reflected by arthritis activity (Juvenile Arthritis Disease Activity Score (JADAS-71)), function, pain, and psychosocial stresses using a linear mixed model approach. Results in the JIA cohort were compared to normative Pediatric Bone Mineral Accrual Study data derived from healthy children using z-scores. RESULTS: At enrollment, PA z-score levels of study participants were lower than those in the normative population (median z-score - 0.356; p = 0.005). At enrollment, PA raw scores were negatively associated with the psychosocial domain of the Juvenile Arthritis Quality of Life Questionnaire (r = - 0.251; p = 0.023). There was a significant decline in PAQ-C/A raw scores from baseline (median and IQR: 2.6, 1.4-3.1) to 24 months (median and IQR: 2.1, 1.4-2.7; p = 0.003). The linear mixed-effect model showed that PAQ-C/A raw scores in children with JIA decreased as age, disease duration, and ESR increased. The PAQ-C/A raw scores of the participants was also negatively influenced by an increase in disease activity as measured by the JADAS-71 (p <  0.001). CONCLUSION: Canadian children with newly diagnosed JIA have lower PA levels than healthy children. The decline in PA levels over time was associated with disease activity and higher disease-specific psychosocial stress.

Malignancies in juvenile idiopathic arthritis: a preliminary report.

OBJECTIVE: To present preliminary data on incidence of malignancy in juvenile idiopathic arthritis (JIA), compared to general population rates. METHODS: We examined cancer occurrence within JIA registries at 3 Canadian pediatric rheumatology centers. The subjects in the clinic registries were linked to regional tumor registries to determine the occurrence of invasive cancers over the observation period (spanning 1974-2006). The total number of cancers expected was determined by multiplying the person-years in the cohort by age, sex, and calendar year-specific cancer rates. The standardized incidence ratio (SIR, ratio of cancers observed to expected) was generated, with 95% confidence intervals. RESULTS: The study sample consisted of 1834 patients. The female proportion was 67.6%; average age at entry to cohort was 8.6 years (SD 5.1). The majority were Caucasian. Subjects contributed 22,341 patient-years (average 12.2, SD 7.8). Within this observation period, one invasive cancer occurred, compared to 7.9 expected (SIR 0.12, 95% CI 0.0, 0.70). This was a hematological cancer (Hodgkin's lymphoma), representing a SIR for hematological malignancies of 0.76 (95% CI 0.02, 4.21). CONCLUSION: Only one invasive cancer was identified in this large sample of individuals with JIA, observed for an average of 12.2 years each. These data suggest that, at least in the initial years following diagnosis of JIA, the risk of invasive cancers overall is not markedly increased. The results do not rule out the possibility of a baseline increased risk of hematological malignancies.

Corticosteroid treatment of refractory Kawasaki disease.

OBJECTIVE: To review the indications for corticosteroids in patients with Kawasaki disease (KD) treated by pediatric rheumatologists in Canada and to determine their efficacy on fever in patients with refractory KD. METHODS: All practicing pediatric rheumatologists in Canada identified KD patients treated with corticosteroids and completed a standard data form that included demographics, clinical and laboratory features, imaging studies, and therapeutic interventions, by chart review. RESULTS: Thirty-two patients with KD (14 female; 18 male: mean age 4.6 years) were treated with corticosteroids. Corticosteroids were used in 26 patients (81%) for persistent fever despite treatment with intravenous immunoglobulin (IVIG) (refractory KD), 5 patients (19%) for congestive heart failure, and 1 patient for persistent acute phase symptoms other than fever. The 26 patients with refractory KD are the primary subject of this report. Twenty-two patients (85%) had rapid, sustained resolution of fever after corticosteroids. There were no serious reported adverse effects. Eight patients (31%) treated with corticosteroids developed coronary artery (CA) aneurysms and 9 (35%) developed CA dilatations without aneurysms. Of those who developed CA aneurysm, 4 had aneurysms detected prior to IV methylprednisolone (MP) on echocardiograms performed on days 6-27 (mean day 13) of illness. The remaining 4 patients had CA aneurysm detected after IVMP therapy, on echocardiograms performed on days 13-49 (mean day 23) of illness, 1-25 days (mean 9 days) after IVMP. In patients with one year or more of followup, 46% had resolution of CA abnormalities. CONCLUSION: Corticosteroids are effective in the treatment of fever in most patients with IVIG-refractory KD. A multicenter prospective study is needed to determine the effect of corticosteroids on CA outcome in patients with refractory KD.