Association of Infant Breastfeeding and Juvenile Spondyloarthritis: A Case-Control Study.

OBJECTIVE: Given the multifactorial pathogenesis of juvenile spondyloarthritis (JSpA) and evidence of a protective effect in phenotypically similar diseases, we aimed to test whether breastfeeding is associated with the development and disease activity of JSpA. METHODS: This single-center retrospective case-control study included children with JSpA and age- and sex-matched controls with a 1:1 ratio. Univariable and multivariable conditional logistic regression modeling for matched pairs was used to test the association of infant factors with the development of JSpA, including infant nutrition and form of delivery. Linear regression was used to assess the association of JSpA disease activity (JSpA Disease Activity Index with 6 elements [JSpADA6]) at presentation with breastfeeding exposure, form of delivery, and antibiotic exposure. RESULTS: For the 195 case-control matched pairs, the mean age was 13.0 years and 47.7% were female. For breastfeeding, 88.7% of controls and 69.2% of JSpA cases were exposed to breastfeeding of any duration, respectively (P < 0.001). In the multivariable model, exclusive breastfeeding > 6 months was independently and significantly associated with a lower chance of JSpA development (odds ratio 0.47, 95% CI 0.30-0.72; P < 0.001). The median JSpADA6 was not significantly associated with breastfeeding for > 6 months. However, vaginal delivery was significantly associated with a lower JSpADA6 (B = -0.65, 95% CI -1.13 to -0.17; P = 0.008). CONCLUSION: This study suggests that infant factors that affect the microbiome may be associated with the occurrence and disease activity of JSpA at presentation.

Consensus-Driven Definition for Unequivocal Sacroiliitis on Radiographs in Juvenile Spondyloarthritis.

OBJECTIVE: Radiography is still used worldwide for the detection of sacroiliitis in juvenile spondyloarthritis (JSpA), despite its low sensitivity and reliability. We aimed to define unequivocal evidence of sacroiliitis on pelvic radiography in skeletally immature youth for use in classification criteria when magnetic resonance imaging (MRI) is unavailable. METHODS: Subjects were a retrospective cohort of juvenile patients with spondyloarthritis with a radiograph and MRI as part of a diagnostic evaluation for axial disease. Six musculoskeletal imaging experts underwent an iterative consensus process to define unequivocal sacroiliitis on radiography in skeletally immature youth. Radiographs were graded using the modified New York (mNY) criteria and the unequivocal sacroiliitis criteria. Interrater agreement was assessed with the Fleiss [Formula: see text] statistic. Specificity, area under the receiver operator characteristic curve (AUROC), and sensitivity of the 2 measures were tested using 2 MRI reference standards. RESULTS: A total of 112 subjects, with a median age of 14.9 (range 6.7-20.1) years, were included. The Fleiss [Formula: see text] was fair for the mNY criteria (0.54, 95% CI 0.42-0.67) and the unequivocal sacroiliitis criteria (0.58, 95% CI 0.46-0.69). The unequivocal sacroiliitis criteria achieved > 90% specificity using both MRI reference standards. Sensitivity (59.26 and 57.14 vs 44.83 and 43.33) and AUROC (0.76 and 0.76 vs 0.71 and 0.71) were higher, for both reference standards, for the unequivocal sacroiliitis in youth definition than for the mNY criteria, respectively. CONCLUSION: In this study, we propose the first consensus-derived definition to our knowledge of unequivocal sacroiliitis by radiography in skeletally immature youth. This definition achieved excellent specificity and had higher AUROC and sensitivity values than the mNY criteria using both MRI reference standards. This definition has applicability to the JSpA axial disease classification imaging criterion when MRI is unavailable.

Biologic Abatement and Capturing Kids' Outcomes and Flare Frequency in Juvenile Spondyloarthritis (BACK-OFF JSpA): study protocol for a randomized pragmatic trial.

BACKGROUND: The effectiveness of biologic therapies, primarily tumor necrosis factor inhibitors (TNFi), for children with spondyloarthritis (SpA) has made inactive disease a realistic patient outcome. However, biologic therapies are costly, primarily delivered by subcutaneous or intravenous route, and have non-trivial side effects. Many patients and families want to know if biologic medications can be discontinued after inactive disease is achieved. It remains unclear whether medication dose should remain unchanged, tapered (increase the time between doses), or discontinued once when inactive disease is attained. METHODS: The Biologic Abatement and Capturing Kids' Outcomes and Flare Frequency in Juvenile SpA (BACK-OFF JSpA) trial is a multicenter pragmatic trial that will randomize 198 participants ages 8-21 years old with SpA and sustained inactive disease on standard TNFi dosing to (1) continue standard TNFi dosing, (2) fixed longer dosing intervals of TNFi, or (3) stop TNFi. The trial will compare the hazard rate of protocol-defined flare and participants' emotional health among the 3 groups over 12 months. Innovative aspects of this trial are the involvement of patient and parent stakeholders in the design and conduct of the study as well as an electronic health record-based enhanced recruitment strategy. DISCUSSION: This is the first randomized pragmatic trial to assess the efficacy of TNFi de-escalation strategies in children with JSpA with sustained inactive disease. This research will improve the evidence base that patients, caregivers, and rheumatologists use to make shared decisions about continued treatment versus de-escalation of TNFi therapy in this population. TRIAL REGISTRATION: ClinicalTrials.gov NCT04891640. Registered on 18 May 2021.

Development and Validation of a Juvenile Spondyloarthritis Disease Flare Measure: Ascertaining Flare in Patients With Inactive Disease.

OBJECTIVE: Our objective was to develop and validate a composite disease flare definition for juvenile spondyloarthritis (SpA) that would closely approximate the clinical decision made to reinitiate or not reinitiate systemic therapy after therapy de-escalation. METHODS: Retrospective chart reviews of children with SpA who underwent systemic therapy de-escalation of biologic or conventional disease-modifying antirheumatic drugs were used to develop and validate the flare outcome. Data on independent cohorts for development (1 center) and validation (4 centers) were collected from large tertiary health care systems. Core measure thresholds and candidate disease flare outcomes were assessed using sensitivity, specificity, positive predictive values (PPVs) and negative predictive values (NPVs), and the receiver operating characteristic (ROC) area under the curve (AUC), with physician assessment of active disease plus re-initiation of standard dose of systemic therapy as the reference standard. RESULTS: Of the candidate definitions, clinically meaningful worsening in ≥3 of the following 5 core measures performed best: caregiver/patient assessment of well-being; physician assessment of disease activity; caregiver/patient assessment of pain, physical function, and active joint count. The ROC AUC was 0.91, PPV 87.5%, NPV 98.1%, sensitivity 82.4%, and specificity 98.7%. Cronbach's α was 0.81, signifying internal consistency, and factor analysis demonstrated that the outcome measured 1 construct. The Juvenile SpA Flare measure had face validity according to 21 surveyed pediatric rheumatologists. Juvenile SpA Flare had an ROC AUC of 0.85, a PPV of 92.3%, and an NPV of 96.8% in the validation cohort. CONCLUSION: There is initial support for the validity of the Juvenile SpA Flare measure as a tool to identify disease flare in juvenile SpA patients de-escalating therapy, and the measure is potentially applicable in clinical practice, observational studies, and therapeutic trials.

Stakeholder outcome prioritization in the Biologic Abatement and Capturing Kids' Outcomes and Flare Frequency in Juvenile Spondyloarthritis (BACK-OFF JSpA) trial.

BACKGROUND: The Biologic Abatement and Capturing Kids' Outcomes and Flare Frequency in Juvenile Spondyloarthritis (BACK-OFF JSpA) study is a randomized, pragmatic trial investigating different tumour necrosis factor inhibitor de-escalation strategies for children with sustained inactive disease. In this project, we elicited concept rankings that aided in the selection of the patient-reported outcome (PRO) measures that should be examined as part of the BACK-OFF JSpA trial. METHODS: We conducted a discrete choice experiment to evaluate individuals' preferences regarding PROs. Stakeholders assessed a discrete list of 21 outcome concepts, each of which had a Patient-Reported Outcome Measurement Information System (PROMIS) measure associated with it. PROMIS measures are self- or proxy-reported instruments that are universally applicable to the general population and all chronic conditions. Stakeholders were required to make choices instead of expressing the strength of a preference. RESULTS: Fourteen caregivers, 12 patients (9-22 years old), 16 rheumatologists and three executives from health insurance companies completed the exercise, which took approximately 10 min. The discrete choice experiment resulted in an estimate of the relative importance of each outcome and rank. All stakeholder groups agreed that the primary PRO should be 'Pain Interference', a measure that evaluates the effect of pain on a child's everyday activities, including its impact on social, emotional, mental and physical functioning. Patients and caregivers were mostly aligned in their top priorities, with patients valuing physical health (50% of the top 10) whereas caregivers were more interested in mental health (60% of the top 10). Rheumatologists and health insurance executives were most interested in physical health outcomes, which were ranked 80% and 60% of their top 10 PROs, respectively. Overall, the patients had the most diverse set of prioritized outcomes, including at least one of each category in their top 10 rank order of importance. Patients were also the only stakeholders to prioritize 'social' health. CONCLUSIONS: Patients and caregivers were mostly aligned in their outcome priority rankings. The rank-order list directly informed the creation of a profile of PRO measures for our upcoming trial. PATIENT OR PUBLIC CONTRIBUTION: Stakeholder partners helped with acquisition of data and lead parent partners helped interpret data.

Data-Driven Magnetic Resonance Imaging Definitions for Active and Structural Sacroiliac Joint Lesions in Juvenile Spondyloarthritis Typical of Axial Disease: A Cross-Sectional International Study.

OBJECTIVE: We aimed to determine quantitative sacroiliac (SI) joint magnetic resonance imaging (MRI) cutoffs for active and structural lesions that will be incorporated as imaging domains in classification criteria of axial disease in juvenile spondyloarthritis (SpA). METHODS: MRI scans from an international cross-section of juvenile SpA patients were reviewed by 6 musculoskeletal imaging experts blinded to clinical details. Raters globally assessed the presence/absence of lesions typical of axial SpA and performed SI joint quadrant- or joint-based scoring. Sensitivity and specificity of lesion cutoffs were calculated using a rater majority (≥4 of 6 raters) on a global assessment of the presence/absence of active or structural lesions typical of axial SpA with high confidence as the reference standard. Cutoffs were validated in an independent cohort. RESULTS: Imaging from 243 subjects, 61% male, median age 14.9 years, had sequences available for detailed MRI scoring. Optimal cutoffs for defining lesions typical of axial disease in juvenile SpA were: 1) inflammatory lesion: bone marrow edema in ≥3 SI joint quadrants across all SI joint MRI slices (sensitivity 98.6%, specificity 96.5%); 2) structural lesions: erosion in ≥3 quadrants or sclerosis or fat lesion in ≥2 SI joint quadrants or backfill or ankylosis in ≥2 joint halves across all SI joint MRI slices (sensitivity 98.6%, specificity 95.5%). Sensitivity and specificity of the optimal cutoffs in the validation cohort were excellent. CONCLUSION: We propose data-driven cutoffs for active inflammatory and structural lesions on MRI typical of axial disease in juvenile SpA that have high specificity and sensitivity using central imaging global assessment as the reference standard and excellent reliability.

Incidence Rates of Psoriasis in Children With Inflammatory Bowel Disease and Juvenile Arthritis Treated With Tumor Necrosis Factor Inhibitors and Disease-Modifying Antirheumatic Drugs.

OBJECTIVE: To estimate the differential effect of tumor necrosis factor inhibitor (TNFi) therapies and presence or absence of conventional synthetic disease-modifying antirheumatic drugs (DMARDs) on the incidence of psoriasis (PsO) in children with inflammatory bowel disease (IBD), juvenile idiopathic arthritis (JIA), and chronic nonbacterial osteomyelitis (CNO). METHODS: This was a retrospective cohort study from 2008 to 2020. TNFi and DMARD exposures were dichotomized as ever/never. The primary outcome was incident PsO. Incidence rates (IRs) of PsO were stratified by underlying diagnosis, TNFi agent, and DMARD use. Poisson regression was used to assess the IR ratios (IRRs) between exposure groups. RESULTS: There were 5088 children who met the inclusion criteria: 3794 (75%) had IBD, 1189 (23%) had JIA, and 105 (2%) had CNO. Of the 2023 children with TNFi exposure, 613 (30%) and 1410 (70%) were with or without a DMARD, respectively. When controlling for DMARD, sex, and family history of PsO, the IRR of developing PsO in patients exposed to adalimumab (ADA) was 2.70 times higher (95% CI 1.53-4.75; P < 0.001) than those who did not receive any TNFi treatment. IRR was lower, but not significantly different, for patients exposed to infliximab (IFX; IRR 2.34, 95% CI 1.56-3.51; P < 0.001) and etanercept (ETN; IRR 2.21; 95% CI 1.17-4.21; P = 0.006) compared to TNFi-unexposed patients. IRR of TNFi exposure was lower by 0.25 (P < 0.001) in DMARD-exposed patients compared to non-DMARD-exposed patients. CONCLUSION: IRR of TNFi-induced PsO was not significantly different among ADA, IFX, and ETN. However, for patients with exposure to any of the TNFi evaluated, the IRR was significantly lower in those also exposed to a DMARD.

Clinical features, treatment patterns and short-term outcomes of children with inflammatory bowel disease evaluated in rheumatology clinic.

OBJECTIVES: This study evaluated the clinical features, treatment patterns, and short-term outcomes of children with inflammatory bowel disease (IBD)-associated musculoskeletal manifestations. METHODS: This was a retrospective cohort study of children with IBD evaluated for joint complaints in a paediatric rheumatology clinic from 2015 to 2020. The index visit was the date of initial rheumatology evaluation. Clinical features were evaluated using standard descriptive statistics. Differences in outcomes over time were compared using rank-sum tests. Univariate logistic regression was used to test associations between clinical features and persistent arthritis or enthesitis. RESULTS: Seventy-five patients met inclusion criteria. 61% had active arthritis or enthesitis at initial evaluation, 1/3 of whom were not yet diagnosed with IBD. Of those with known IBD, over half with joint complaints had arthritis or enthesitis. Active joint disease was common even among patients already receiving tumour necrosis factor (TNF) inhibitors or other immunomodulatory medications for IBD and despite inactive gastrointestinal disease. Treatment escalation was often needed to control articular disease, which included changes in immunomodulatory therapy and NSAIDs. Treatment outcomes for arthritis were good and significant improvements in functional mobility were observed (p<0.01), while enthesitis often persisted at follow-up (11/28, 39%). Moreover, a significant proportion of patients with pain at the index visit reported persistent pain at follow-up (29/44, 65%). CONCLUSIONS: This study provides several findings relevant to the multidisciplinary care of children with IBD, including high rates of active arthritis and enthesitis despite ongoing use of immunomodulatory medications for the management of IBD, responses to treatment, and pain management.

Feasibility of T2 Mapping of the Sacroiliac Joints in Healthy Control Subjects and Children and Young Adults with Sacroiliitis.

OBJECTIVE: To assess the feasibility of T2 mapping for evaluating pediatric SIJ cartilage at 3 Tesla (T) magnetic resonance imaging (MRI). METHODS: Healthy control subjects and adolescents with sacroiliitis underwent a 3T MRI dedicated pelvic protocol that included a T2 mapping sequence consisting of multislice, multiecho acquisition. Healthy control subjects were prospectively recruited from our primary care practices as part of a larger imaging study, whereas adolescents with sacroiliitis were recruited specifically for this study. Regions of interest (ROIs) were hand-drawn by a senior pediatric radiologist twice and a radiology fellow twice to calibrate and test reliability using the intraclass correlation coefficient (ICC). T2 relaxation time between control subjects and cases was compared using univariate linear regression. We tested the association of T2 relaxation time in adolescents with sacroiliitis with patient-reported outcomes and the Spondyloarthritis Research Consortium of Canada sacroiliac joint (SIJ) inflammation and structural scores using Pearson correlation coefficients. RESULTS: Fourteen subjects were evaluable (six control subjects: median age 13.7 years [interquartile range (IQR): 12.2-15.5], 67% male patients; eight cases: median age 17.4 years [IQR: 12.5-20], 88% male patients]. Acquisition time for T2 mapping sequences was approximately 6 minutes, and segmenting the ROI for each SIJ took approximately 3 minutes. The intrarater and inter-rater ICCs were 0.67 and 0.46, respectively, indicating good to fair reliability. There was a trend, albeit statistically insignificant, in longer median T2 relaxation time in cases (43.04 ms; IQR: 41.25-49.76 ms) versus healthy control subjects (40.0 ms; IQR: 38.9-48.6 ms). Although not statistically significant, cases with longer T2 relaxation time tended to occur with poorer patient-reported outcomes. Correlations with the SIJ inflammation and structural lesion scores were weak. CONCLUSION: T2 mapping of the SIJ cartilage in children was feasible and reliable. Larger controlled and longitudinal assessments are needed to assess the validity and utility of these measurements for routine clinical practice and trials.

Changes over time in inflammatory and structural lesions at the sacroiliac joint in children with spondyloarthritis exposed and unexposed to tumor necrosis factor inhibitor.

BACKGROUND: The objective of this work was to describe magnetic resonance imaging (MRI) changes over time in inflammatory and structural lesions at the sacroiliac joint (SIJ) in children with spondyloarthritis (SpA) exposed and unexposed to tumor necrosis factor inhibitor (TNFi). METHODS: This was a retrospective, multicenter study of SpA patients with suspected or confirmed sacroiliitis who underwent at ≥2 pelvic MRI scans. Images were reviewed independently by 3 radiologists and scored for inflammatory and structural changes using the Spondyloarthritis Research Consortium of Canada (SPARCC) SIJ inflammation score (SIS) and structural score (SSS). Longitudinal, quantitative changes in patient MRI scans were measured using descriptive statistics and stratified by TNFi exposure. We used an average treatment effects (ATE) regression model to explore the average effect of TNFi exposure over time on inflammatory and structural lesions, adjusting for baseline lesion scores. RESULTS: Forty-six subjects were evaluated using the SIS (n = 45) and SSS (n = 18). Median age at baseline imaging was 13.6 years, 63% were male and 71% were white. Twenty-three subjects (50%) were TNFi exposed between MRI studies. The median change in SIS in TNFi exposed and unexposed subjects with a baseline SIS ≥0 was - 20.7 and - 14.3, respectively (p = 0.09). Eleven (85%) TNFi exposed and 8 (89%) unexposed subjects with a baseline SIS ≥0 met the SIS minimal clinically important difference (MCID; ≥2.5). Using the ATE model adjusted for baseline SIS, the average effect of TNFi on SIS in patients with a baseline SIS ≥2 was - 14.5 (p < 0.01). Unadjusted erosion change score was significantly worse in TNFi unexposed versus exposed subjects (p = 0.03) but in the ATE model the effect of TNFi was not significant. CONCLUSION: This study quantitatively describes how lesions in the SIJs on MRI change over time in patients exposed to TNFi versus unexposed. Follow-up imaging in TNFi exposed patients showed greater improvement than the unexposed group by most metrics, some of which reached statistical significance. Surprisingly, a majority of TNFi unexposed children with a baseline SIS≥2 met the SIS MCID. Additional studies assessing the short and long-term effects of TNFi on inflammatory and structural changes in juvenile SpA are needed.

Variability in Interpretation of Magnetic Resonance Imaging of the Pediatric Sacroiliac Joint.

OBJECTIVE: Magnetic resonance imaging (MRI) is pivotal in the assessment of early sacroiliitis in children. We aimed to evaluate the agreement between local radiology reports and central imaging reviewers for active inflammation and structural damage at the sacroiliac (SI) joints. METHODS: Eight hospitals each contributed up to 20 cases of consecutively imaged children and adolescents with juvenile idiopathic arthritis and suspected sacroiliitis. Studies were independently reviewed by 3 experienced musculoskeletal pediatric radiologists. Local assessments of global impression and lesions were coded from the local radiology reports by 2 study team members. Test properties of local reports were calculated using the central imaging team's majority as the reference standard. RESULTS: For 120 evaluable subjects, the median age was 14 years, half of the cases were male, and median disease duration at the time of imaging was 0.8 years (interquartile range 0-2). Sensitivity of local reports for inflammation was high, 93.5% (95% confidence interval [95% CI] 78.6-99.2), and specificity was moderate, 69.7% (95% CI 59.0-79.0), but positive predictive value (PPV) was low, 51.8% (95% CI 38.0-65.3). Twenty-seven cases (23%) had active inflammation reported locally but rated normal at the central reading, 19 (70%) with subsequent medication changes. The sensitivity of local reports detecting structural damage was low, 45.7% (95% CI 28.8-63.4), and specificity was high, 88.2% (95% CI 79.4-94.2); PPV was low, 61.5% (95% CI 40.6-79.8). CONCLUSION: Substantial variation exists in the interpretation of inflammatory and structural lesions at the SI joints in children. To reliably identify pathology, additional training in the MRI appearance of the maturing SI joint is greatly needed.

Determinants of disease activity change over time in Enthesitis related arthritis: effect of structured outcome monitoring and clinical decision support.

BACKGROUND: We aimed to test if standardized point-of-care outcome monitoring and clinical decision support (CDS), as compared to standard care, improves disease activity and patient-reported pain in children with enthesitis-related arthritis (ERA). METHODS: This was a retrospective cohort study of outcomes of children with ERA after phased implementation of I) standardized outcome monitoring with CDS for polyarticular JIA, and II) CDS for ERA, compared to a pre-intervention group of historical controls. We used multivariable mixed-effects models for repeated measures to test whether implementation phase or other disease characteristics were associated with change over time in disease activity, as measured by the clinical juvenile arthritis disease activity score (cJADAS), and pain. RESULTS: One hundred fifty-two ERA patients (41% incident cases) were included with a median age of 14.9 years. Implementation of standardized outcome monitoring or ERA-specific CDS did not result in significant differences in cJADAS or pain over time compared to the pre-intervention cohort. Higher cJADAS at the index visit, pain and more tender entheses were significantly associated with higher cJADAS scores over time (all p < 0.01), while biologic use was associated with lower cJADAS (p = 0.02). Regardless of intervention period, incident ERA cases had a greater rate of cJADAS improvement over time compared to prevalent cases (p < 0.01), but pain persisted over time among both incident and prevalent cases. CONCLUSIONS: There was no significant effect of point-of-care outcome monitoring or CDS interventions on disease activity or pain over time in children with ERA in this single center study. Future efforts to improve disease outcomes using standardized outcome monitoring and CDS will need to consider the importance of addressing pain as a target in addition to spondyloarthritis-specific disease activity metrics.

Juvenile Spondyloarthritis: focus on uveitis.

BACKGROUND: Juvenile spondyloarthritis (JSpA) represents a group of inflammatory arthritides with several distinctive features (enthesitis, involvement of spine and sacroiliac joint, HLA-B27 association and development of uveitis). There are limited data on the course of uveitis in children with JSpA. This study aims to estimate the prevalence of uveitis and to look at the presence of HLA-B27 in relation to uveitis occurrence and ocular symptoms in a cohort of JSpA patients. FINDINGS: This is a cross sectional/retrospective study involving patients with JSpA followed in a tertiary referral hospital. Two hundred twenty-three patients were enrolled in the study. The prevalent diagnosis was enthesitis-related arthritis (ERA) (62%) followed by juvenile psoriatic arthritis (PsA), undifferentiated arthritis (UA), and the arthropathies associated with inflammatory bowel disease (IBD-A) (18, 14, 6%, respectively). Uveitis was reported in twenty-four patients (11%) of the JSpA cohort (JSpA-U). ERA patients had the highest uveitis prevalence (ERA-U) (13%) with similar prevalences in UA, PsA and in IBD-A (7% each). The prevalence of HLA-B27 positivity was similar amongst the entire JSpA-U cohort (N = 22, 45%) and those with ERA-U (N = 8, 44%). The overall prevalence of symptomatic uveitis was 79%. Neither the likelihood of uveitis, nor of symptomatic uveitis, varied by HLA-B27 status either in the entire cohort nor in those with ERA. CONCLUSIONS: About one-tenth of patients developed uveitis, the majority of which was symptomatic. Fewer than half of the patients with uveitis were HLA-B27 positive. HLA-B27 status was not statistically associated with either the development of uveitis or symptomaticity of uveitis.

Normal hip joint fluid volumes in healthy children of different ages, based on MRI volumetric quantitative measurement.

BACKGROUND: While magnetic resonance imaging (MRI) of the pelvis and hips is common in pediatric patients, to date there are no data on the quantification of normal hip joint fluid volume in this patient population. OBJECTIVE: We sought to assess the feasibility and reliability of quantitative hip joint fluid measurement in the pediatric population to estimate the normal volume of fluid in a pediatric hip joint. MATERIALS AND METHODS: Seventy healthy children ages 8-17 years underwent a pelvic MRI including a large field of view coronal T2 fat-saturated sequence where hips were entirely imaged. Following 3 training sessions, 2 readers with experience in musculoskeletal imaging performed volumetric quantitative measurements of hip fluid (140 hips) using semiautomated pixel-based thresholding on custom MATLAB software. RESULTS: The mean processing time per hip was 2 min, 41 s. The mean volume of fluid in a hip joint was 2.1 mL (range: 0.38-5.41 mL), increasing slightly with age. Volumes were also greater in boys than in girls (P=0.004). Intra-observer and interobserver agreement were high (intra-class correlation coefficients 0.93 and 0.98, respectively), with mean volume differences of 0.04 mL for intra-observer and 0.09 mL for interobserver. CONCLUSION: A semiautomated pixel-based thresholding approach was feasible and reliable for measuring joint fluid in pediatric hip MRI. The average fluid volume of 2.1 mL can represent a visually substantial quantity of fluid per MRI slice, particularly in small children, and should not be misinterpreted as a joint effusion.

Spondyloarthritis Research Consortium of Canada sacroiliac joint inflammation and structural scores: change score reliability and recalibration utility in children.

BACKGROUND: The SPARCC sacroiliac joint inflammation (SIS) and structural (SSS) scores are reliable measures to quantify abnormalities in the pediatric sacroiliac joint. We aimed to evaluate the utility of online calibration modules for the SIS and SSS and the reliability of their component change scores. METHODS: Change score reliability of 6 raters was assessed by overall and pairwise intraclass correlation coefficients (ICCs) before and after the use of real-time iterative calibration (RETIC) modules for both the SIS and SSS comprised of 20 adult cases. Acceptable ICC for change scores was > 0.7 for SIS and > 0.5 for all SSS components. Sensitivity to change was assessed by the standardized response mean (SRM). RESULTS: In scoring exercise 1, the SIS had acceptable reliability with a change score ICC of 0.80 and sclerosis was the only SSS lesion that met the acceptability threshold with a change score ICC of 0.52. After RETIC calibration, the SIS overall (ICC = 0.83) and mean pairwise (ICC = 0.83) change scores remained reliable with a large SRM (0.90). All SSS components except sclerosis met the overall and mean pairwise change score ICC acceptability thresholds-backfill: overall = 0.54, mean pairwise = 0.50; fat metaplasia: overall = 0.65, mean pairwise = 0.57; erosion: overall = 0.60, mean pairwise = 0.58; and ankylosis: overall = 0.96, mean pairwise = 0.96. The SSS RETIC module augmented the number of SSS components surpassing the acceptability threshold from 1 to 4. Sensitivity to change, as measured by the SRM, was large for erosion (0.96), moderate for backfill (0.55) and sclerosis (0.70), and small for fat metaplasia (0.36) and ankylosis (0.28). CONCLUSION: RETIC modules improved the overall reliability of SPARCC SIS and SSS change scores for previously calibrated raters. SIS recalibration was not as helpful to the most experienced raters who achieved high levels of agreement before recalibration. The SPARCC SIS and all SSS components except sclerosis are reliable measures to quantify change over time in children. A pediatric-specific RETIC tool should be developed to enhance the calibration of readers.

MRI of the Sacroiliac Joint in Healthy Children.

To listen to the podcast associated with this article, please select one of the following: iTunes, Google Play, or direct download. OBJECTIVE. Increasing reliance on MRI for the evaluation of sacroiliitis requires that radiologists be familiar with the normal appearance of the developing sacroiliac joint. We describe age-related MRI features of the sacroiliac joints in healthy children. SUBJECTS AND METHODS. Seventy healthy children from three age groups-prepubertal (8-10 years), peripubertal (11-13 years), and approaching skeletal maturity (14-17 years)-completed questionnaires and underwent sacroiliac joint MRI. Imaging studies were evaluated by three experienced pediatric radiologists. Metaphyseal-equivalent signal intensity, nonperiarticular osteitis, cartilage volume, joint fluid, enthesitis, and surface cortex irregularities were evaluated. Metaphyseal-equivalent signal intensity was evaluated using an ordinal grading system (types I-IV). Intraclass correlation coefficients were calculated to assess interrater reliability. RESULTS. Increased metaphyseal-equivalent signal intensity (types I and II) was present in most prepubertal children and in less than 10% of the group approaching skeletal maturity. More prepubertal girls had type I signal than boys, but signal progressed to type IV signal faster in girls than in boys. None of the subjects had subchondral marrow edema, but four subjects had nonperiarticular osteitis. Cartilage volumes decreased with advancing age in girls and, on average, were lower in girls than in boys of the same age. One subject had measurable joint fluid. Cortex irregularities were common (57.1%), most frequently seen along the iliac bone (51.4% ilium vs 11.4% sacrum, p < 0.01) and in the upper quadrants (42.8% upper vs 27.1% lower, p = 0.01). CONCLUSION. We provide valuable reference MRI descriptions of the healthy pediatric sacroiliac joint that should improve our ability to distinguish between normal and pathologic findings.

Radiographs in screening for sacroiliitis in children: what is the value?

BACKGROUND: We aimed to evaluate the diagnostic utility of pelvic radiographs versus magnetic resonance imaging (MRI) of the sacroiliac joints in children with suspected sacroiliitis. METHODS: This was a retrospective cross-sectional study of children with suspected or confirmed spondyloarthritis who underwent pelvic radiograph and MRI within 6 months of one another. Images were scored independently by five raters. Interrater reliability was calculated using Fleiss's kappa coefficient (κ). Test properties of radiographs for depiction of sacroiliitis were calculated using MRI global sacroiliitis impression as the reference standard. RESULTS: The interrater agreement for global impression was κ = 0.34 (95% CI 0.19-0.52) for radiographs and κ = 0.72 (95% CI 0.52-0.86) for MRI. Across raters, the sensitivity of radiographs ranged from 25 to 77.8% and specificity ranged from 60.8 to 92.2%. Positive and negative predictive values ranged from 25.9 to 52% and from 82.7 to 93.9%, respectively. The misclassification rate ranged from 6 to 17% for negative radiographs/positive MRI scans and from 48 to 74% for positive radiographs/negative MRI scans. When the reference standard was changed to structural lesions consistent with sacroiliitis on MRI, the misclassification rate was higher for negative radiographs/positive MRI scans (9-23%) and marginally improved for positive radiographs/negative MRI scans (33-52%). CONCLUSION: Interrater reliability of MRI was superior to radiographs for global sacroiliitis impression. Misclassification for both negative and positive radiographs was high across raters. Radiographs have limited utility in screening for sacroiliitis in children and result in a significant proportion of both false negative and positive findings versus MRI findings.

Feasibility and Reliability of the Spondyloarthritis Research Consortium of Canada Sacroiliac Joint Structural Score in Children.

OBJECTIVE: There is a critical need for measures to evaluate structural progression in the pediatric sacroiliac joint (SIJ). We aimed to evaluate the construct validity and reliability of the Spondyloarthritis Research Consortium of Canada SIJ Structural Score (SSS) in children with suspected or confirmed juvenile spondyloarthritis. METHODS: The SSS assesses structural lesions of the SIJ on magnetic resonance imaging (MRI) through the cartilaginous part of the joint. We conducted 3 sequential reading exercises with 6 readers (1 adult and 3 pediatric radiologists, 1 adult and 1 pediatric rheumatologist). Each exercise was preceded by a calibration module. Interobserver reliability was assessed using intraclass correlation coefficients (ICC). Prespecified acceptable reliability thresholds were ICC > 0.5 for erosion, backfill, and sclerosis, and ICC > 0.7 for ankylosis and fat metaplasia. RESULTS: The SSS had face validity and was feasible to score in pediatric cases for all 3 reading exercises. Of the cases used in the 3 exercises, 58% were male and the median age was 14 years (range 6.8-18.7 yrs). After calibration, median ICC across all readers for each SSS component were the following: erosion 0.67 (interquartile range 0.54-0.80), backfill 0.33 (0.19-0.52), fat metaplasia 0.74 (0.62-0.85), sclerosis 0.63 (0.48-0.77), and ankylosis 0.44 (0.28-0.62). Prespecified reliability thresholds were achieved in the third exercise for erosion, sclerosis, and fat metaplasia but not for backfill or ankylosis. CONCLUSION: The SSS was feasible to score and had acceptable reliability for pediatric SIJ MRI evaluation. The ICC improved with additional calibration and reading exercises, even for readers with limited experience.

Feasibility and reliability of the Spondyloarthritis Research Consortium of Canada sacroiliac joint inflammation score in children.

BACKGROUND: Published methods for quantification of magnetic resonance imaging (MRI) evidence of inflammation in the sacroiliac joint lack validation in pediatric populations. We evaluated the reliability and construct validity of the Spondyloarthritis Research Consortium of Canada (SPARCC) sacroiliac joint inflammation score (SIS) in children with suspected or confirmed juvenile spondyloarthritis (JSpA). METHODS: The SPARCC SIS measures the presence, depth, and intensity of bone marrow inflammation on MRI through the cartilaginous part of the joint. Six readers blinded to clinical details except age, participated in two reading exercises, each preceded by a calibration exercise. Inter-observer reliability was assessed using intraclass correlation coefficients (ICCs) and for pre-specified acceptable reliability the inraclass correlation coefficient (ICC) was > 0.8. RESULTS: The SPARCC SIS had face validity and was feasible to score in pediatric cases in both reading exercises. Cases were mostly male (64%) and the median age at the time of imaging was 14.9 years. After calibration, the median ICC across all readers for the SIS total score was 0.81 (IQR 0.71-0.89). SPARCC SIS had weak correlation with disease activity (DA) as measured by the JSpADA (r = - 0.12) but discriminated significantly between those with and without elevated C-reactive protein (p = 0.03). CONCLUSION: The SPARCC SIS was feasible to score and had acceptable reliability in children. The ICC improved with additional calibration and reading exercises, for both experienced and inexperienced readers.

Comparative Effectiveness of Tumor Necrosis Factor Agents and Disease-modifying Antirheumatic Therapy in Children with Enthesitis-related Arthritis: The First Year after Diagnosis.

OBJECTIVE: To characterize the effect of anti-tumor necrosis factor (TNF) therapy compared to conventional synthetic disease-modifying antirheumatic drugs (csDMARD) in children with enthesitis-related arthritis (ERA) over the first year after diagnosis. METHODS: We conducted a multicenter retrospective comparative effectiveness study of children diagnosed with ERA. We estimated the effect of anti-TNF therapy on clinical variables (active joint count, tender entheses count) and patient-reported pain and global assessment of disease activity over the first year after diagnosis using state-of-the-art comparative effectiveness analytic methods. RESULTS: During the study period, 217 patients newly diagnosed with ERA had a total of 965 clinic visits the first year after disease diagnosis. Children [median age 11.6 yrs, interquartile range 10-14] were treated with anti-TNF monotherapy (n = 33, 15.2%), csDMARD monotherapy (n = 73, 33.6%), or both (n = 52, 23.9%) in the first year after disease diagnosis. There was a statistically significant improvement in the primary outcome, active joint count, over time in children who received an anti-TNF drug versus those who did not (p = 0.03). Additionally, use of anti-TNF therapy versus no anti-TNF therapy was associated with less patient-reported pain (p < 0.01) and improved disease activity over time as assessed by the clinical Juvenile Arthritis Disease Activity Score (p < 0.01). The magnitude of estimated effect on clinical outcomes was uniformly greater, with the exception of tender entheses count, in children treated with an anti-TNF drug versus a csDMARD. CONCLUSION: During the first year after diagnosis, anti-TNF exposure was associated with benefits for several clinically meaningful outcomes in children with enthesitis-related arthritis.