The Role of Psychology in Pediatric Rheumatic Diseases

Pediatric rheumatic diseases (PRDs) are a heterogeneous group of diseases that can have a chronic unpredictable disease course that can negatively affect mood, functioning, and quality of life. Given the range of difficulties faced in managing PRDs, as well as the psychosocial issues youth with these diseases experience, pediatric psychologists can be well suited to address concerns that arise in care for youth with PRDs including adherence, cognitive assessment, pain management, functional disability, and mood. Potential ways that pediatric psychologists can address these concerns and be embedded within an interdisciplinary treatment plan for youth with PRDs are described.

Clinical Characteristics of Adolescents With Juvenile Idiopathic Arthritis Transitioning to Adult Rheumatology Care in Canada: Results From the CAPRI Registry

OBJECTIVE

Using Canadian Alliance of Pediatric Rheumatology Investigators (CAPRI) juvenile idiopathic arthritis (JIA) registry data, we describe (1) clinical characteristics of patients with JIA transitioning to adult care, (2) prevalence of disease-related damage and complications, and (3) changes in disease activity during the final year prior to transfer.

METHODS

Registry participants who turned 17 years between February 2017 and November 2021 were included. Clinical characteristics and patient-reported outcomes (PROs) at the last recorded pediatric rheumatology visit, and changes observed in the year prior to that visit were analyzed. Physicians completed an additional questionnaire characterizing cumulative disease-related damage and adverse events by age 17 years.

RESULTS

At their last visit, 88 of 131 participants (67%) had inactive and 42 (32%) had active disease. Overall, 96 (73%) were on medications and 41 (31%) were on biologic disease-modifying antirheumatic drugs. Among 80 participants for whom the additional questionnaire was completed, 26% had clinically detected joint damage, 31% had joint damage on imaging, 14% had uveitis, and 7.5% had experienced at least 1 serious adverse event. During the final year, 44.2% of patients were in remission, 28.4% attained inactive disease, and 27.4% became or remained active. Mean scores of PROs were stable overall during that last year, but a minority reported marked worsening.

CONCLUSION

A substantial proportion of youth with JIA transitioning to adult care in Canada had a high disease burden, which was reflected by their degree of disease activity, joint damage, or ongoing medication use. These results will inform pediatric and adult providers of anticipated needs during transition of care.

Body mass index is associated with health-related quality of life and disease characteristics in young adults with juvenile idiopathic arthritis

BACKGROUND

There is a growing interest concerning the relationship between obesity and several medical conditions and inflammation. Nevertheless, there is a lack of studies regarding body mass index (BMI) among patients with juvenile idiopathic arthritis (JIA). Our aim was to investigate the impact of BMI on health-related quality of life (HRQoL) measured with a 36-Item Short Form Survey (SF-36), disease activity, and disability in young adults with JIA.

METHODS

This study is a part of the population-based Nordic JIA cohort study. All newly diagnosed patients with JIA were recruited consecutively between 1997-2000 in specific regions in the Nordic countries. Patients in this sub-study were enrolled from 434 patients who attended their 18-year follow-up visit. Patients were classified according to the World Health Organization (WHO) into four groups based on their BMI. HRQoL, disease characteristics, disability, fatigue, sleep quality, physical activity, pain, comorbidities, and social status were assessed.

RESULTS

Three hundred fifty-five patients from the original study cohort were enrolled in this study and 72% of them were female. Mean age was 23.9 (± SD 4.4) years. A significant relationship was found between the JIA categories and BMI groups (p = 0.014). A significant relationship was also found between BMI and disease activity scores (DAS28) (p = 0.028), disability (p < 0.001), pain (p = 0.013), fatigue (p = 0.035), and sleep quality (p = 0.044). Moreover, a significant relationship between BMI and HRQoL regarding bodily pain (p = 0.010) and general health (p = 0.048) was revealed when adjusted for sex, age, and JIA subtype.

CONCLUSION

We discovered that BMI was significantly related to HRQoL, disease activity, and disability. BMI deserves more attention considering the treatment options and outcome of JIA in young adults.

Significant pain decrease in children with non-systemic Juvenile Idiopathic Arthritis treated to target: results over 24 months of follow up

BACKGROUND

The aim of this study was to compare pain-scores in three targeted treatment-strategies in JIA-patients and to identify characteristics predicting persistent pain.

METHODS

In the BeSt-for-Kids-study 92 DMARD-naïve JIA-patients were randomized in 3 treatment-strategies: 1) initial sequential DMARD-monotherapy 2) initial methotrexate (MTX)/prednisolone-bridging or 3) initial MTX/etanercept. Potential differences in VAS pain scores (0-100 mm) over time between treatment-strategies were compared using linear mixed models with visits clustered within patients. A multivariable model was used to assess the ability of baseline characteristics to predict the chance of high pain-scores during follow-up.

RESULTS

Pain-scores over time reduced from mean 55.3 (SD 21.7) to 19.5 (SD 25.3) mm after 24 months. On average, pain-scores decreased significantly with β -1.37 mm (95% CI -1.726; -1.022) per month. No significant difference was found between treatment-strategies (interaction term treatment arm*time (months) β (95% CI) arm 1: 0.13 (-0.36; 0.62) and arm 2: 0.37 (-0.12; 0.86) compared to arm 3). Correction for sex and symptom duration yielded similar results. Several baseline characteristics were predictive for pain over time. Higher VAS pain [β 0.44 (95% CI 0.25; 0.65)] and higher active joint count [0.77 (0.19; 1.34)] were predictive of higher pain over time, whereas, low VAS physician [ -0.34 (-0.55; -0.06)], CHQ Physical [ -0.42 (-0.72; -0.11)] and Psychosocial summary Score [ -0.42 (-0.77; -0.06)] were predictive of lower pain.

CONCLUSIONS

Treatment-to-target seems effective in pain-reduction in non-systemic JIA-patients irrespective of initial treatment-strategy. Several baseline-predictors for pain over time were found, which could help to identify patients with a high risk for development of chronic pain.

TRIAL REGISTRATION

Dutch Trial Registry number 1574.

An explorative study on proteomic analyses related to inflammation and pain in children with juvenile idiopathic arthritis

BACKGROUND

Our aim was attempting to find proteins involved in the pain process and correlating with pain but not degree of inflammation in children with juvenile idiopathic arthritis (JIA), using a proteomics panel.

METHODS

A total of 87 plasma samples were collected from 51 children with JIA (51 at diagnosis in a higher disease activity state, 18 at follow-up in a lower disease activity state) and 18 healthy controls. Relative levels of 92 proteins related to a wide range of biological processes in inflammation were obtained using a proximity extension assay panel. Comparisons between children with and without JIA, in different disease categories, by juvenile disease activity score (JADAS27) and degree of pain on a visual analogue scale (VAS), were performed using parametric and non-parametric statistical methods.

RESULTS

Nineteen proteins involved in arthritic inflammation, such as interleukin 6 (IL-6) and S100 protein A12, were higher in patients with JIA than controls, seven decreased significantly during treatment, and 18 correlated significantly with JADAS27. Three proteins correlated with pain VAS scores in unadjusted analyses: the glial cell line-derived neurotrophic factor (GDNF), transforming growth factor beta, and IL-18R1. Levels of GDNF correlated significantly with pain VAS scores but not with JADAS27.

CONCLUSIONS

Plasma levels of 18 of 92 tested proteins correlated with degree of disease activity. Levels of three proteins correlated with pain, and levels of one, GDNF, originating from neural cells, correlated with pain without correlating with inflammatory degree, suggesting that it may play a role in pain in JIA. Further studies in larger cohorts are warranted.

The Role of Psychology in Pediatric Rheumatic Diseases

Pediatric rheumatic diseases (PRDs) are a heterogeneous group of diseases that can have a chronic unpredictable disease course that can negatively affect mood, functioning, and quality of life. Given the range of difficulties faced in managing PRDs, as well as the psychosocial issues youth with these diseases experience, pediatric psychologists can be well suited to address concerns that arise in care for youth with PRDs including adherence, cognitive assessment, pain management, functional disability, and mood. Potential ways that pediatric psychologists can address these concerns and be embedded within an interdisciplinary treatment plan for youth with PRDs are described.

Oral health-related quality of life in 4-16-year-olds with and without juvenile idiopathic arthritis

BACKGROUND

Few studies have investigated oral health-related quality of life (OHRQoL) in young individuals with juvenile idiopathic arthritis (JIA). Aims were to investigate whether OHRQoL differs between children and adolescents with JIA compared to controls without JIA, while adjusting for socio-demographic-, behavioral- and oral health-related covariates. Furthermore, to explore whether socio-behavioral and oral health-related covariates of OHRQoL vary according to group affiliation and finally, specifically for individuals with JIA, to investigate whether disease-specific features associate with OHRQoL. We hypothesized that participants with JIA have poorer OHRQoL compared to participants without JIA.

METHODS

In this comparative cross-sectional study participants with JIA (n = 224) were matched to controls without JIA (n = 224). OHRQoL was assessed according to Early Childhood Oral Health Impact Scale (ECOHIS) (4-11-years-olds) and the child version of Oral Impacts on Daily Performances (Child-OIDP) (12-16-years-olds). JIA-specific characteristics were assessed by pediatric rheumatologists and socio-demographic, behavioral and self-reported oral health information collected by questionnaires. Index teeth were examined for caries by calibrated dentists. Multiple variable analyses were performed using logistic regression, reporting odds ratio (OR) and 95% confidence interval (CI). Two-way interactions were tested between group affiliation and the socio-behavioral- and oral health-related variables on the respective outcome variables.

RESULTS

In total, 96 participants with JIA and 98 controls were evaluated according to ECOHIS, corresponding numbers for Child-OIDP was 125 and 124. Group affiliation was not associated with impaired ECOHIS or Child-OIDP in adjusted analyses (OR = 1.95, 95% CI 0.94-4.04 and OR = 0.99, 95% CI 0.46-2.17, respectively). Female adolescents with JIA were more likely than males to report oral impacts according to Child-OIDP. Continued activity or flare was found to adversely affect Child-OIDP, also self-reported outcome measures in JIA associated with Child-OIDP.

CONCLUSIONS

This study did not provide consistent evidence to confirm the hypothesis that children and adolescents with JIA are more likely to have impaired OHRQoL compared to their peers without JIA. However, female adolescents with JIA were more likely than males to report impacts on OHRQoL. Furthermore, within the JIA group, adolescents with continued disease activity, flare or reporting pain, physical disability, had higher risk than their counterparts of impaired OHRQoL.

Association Between Patient‐Reported Outcomes and Treatment Failure in Juvenile Idiopathic Arthritis

Objective

Children with juvenile idiopathic arthritis (JIA) frequently exhibit symptoms months before diagnosis. The aims of this study were to assess whether baseline patient‐reported outcomes (PROs) are associated with changes in JIA pharmacotherapy treatment and whether symptom duration prior to JIA diagnosis is associated with disease activity scores over time.

Methods

This is a retrospective cohort study of patients with an incident diagnosis of JIA. Patient‐reported symptom duration, pain, energy, disease activity, sleep, anxiety, and depression screenings, as well as provider‐reported disease activity and joint count, were collected during routine clinical care. Cox proportional hazards evaluated PROs, disease activity scores, and symptom duration with initial medication failure within 9 months of diagnosis. Multivariate mixed effects linear regression evaluated the association of symptom duration with disease activity scores.

Results

There were 58 children (66% female, 35% oligoarticular JIA) in the cohort. Nearly half of patients failed initial therapy within 9 months. Unadjusted analysis showed that higher energy (hazard ratio [HR]: 0.82; 95% confidence interval [CI]: 0.69‐0.99; P = 0.04) and longer symptom duration (HR: 0.96; 95% CI: 0.93‐0.99; P = 0.03) at diagnosis were protective against medication failure. Adjusted analysis showed that symptom duration prior to diagnosis was protective against medication failure (HR: 0.95; 95% CI: 0.92‐0.99; P = 0.02); there was no association between medication failure and pain, psychiatric symptoms, or disease activity scores. There was a positive association with longer symptom duration and higher disease activity at 30 and 60 days, but this was not sustained.

Conclusion

Higher energy levels and longer symptom duration are protective against initial JIA treatment failures. Initial treatments informed by patient‐reported data could lead to more successful outcomes by changes in treatment paradigms.

Non-disease specific patient-reported outcome measures of health-related quality of life in juvenile idiopathic arthritis: a systematic review of current research and practice

Juvenile idiopathic arthritis (JIA), as a chronic condition, is associated with symptoms negatively impacting health-related quality of life (HRQL). Regarding growing interest in the implementation of the patient-reported outcome measures (PROMs), we aimed to review the non-disease specific PROMs addressing HRQL assessment, potentially useful in the clinical care of JIA and daily practice. A systematic literature search was conducted using MEDLINE/PubMed, Google Scholar, Scopus and Embase databases (1990 to 2021), with a focus on the recent 5-years period. Entry keywords included the terms: “children”, “adolescents”, “JIA”, “chronic diseases”, “HRQL”, “PROMs” and wordings for the specific tools. Several available PROMs intended to measure HRQL, non-specific to JIA, were identified. The presented outcomes differed in psychometric properties, yet all were feasible in assessing HRQL in healthy children and those with chronic diseases. Both EQ-5D-Y and PedsQL have already been tested in JIA, showing relevant reliability, validity, and similar efficiency as disease-specific measurements. For PROMIS® PGH-7 and PGH-7 + 2, such validation and cross-cultural adaptation need to be performed. Considering the future directions in pediatric rheumatology, the large-scale implementation of PROMIS® PGH-7 and PGH-7 + 2 in JIA offers a particularly valuable opportunity. The PROMs reflect the patient perception of the chronic disease and allow to understand child’s opinions. The PROMs may provide an important element of the holistic medical care of patients with JIA and a standardized tool for clinical outcomes, monitoring disease severity and response to treatment.

A multidisciplinary assessment of pain in juvenile idiopathic arthritis

INTRODUCTION

Pain is prevalent in juvenile idiopathic arthritis (JIA). Unknowns regarding the biological drivers of pain complicate therapeutic targeting. We employed neuroimaging to define pain-related neurobiological features altered in JIA.

METHODS

16 male and female JIA patients (12.7 ± 2.8 years of age) on active treatment were enrolled, together with age- and sex-matched controls. Patients were assessed using physical examination, clinical questionnaires, musculoskeletal MRI, and structural neuroimaging. In addition, functional magnetic resonance imaging (fMRI) data were collected during the resting-state, hand-motor task performance, and cold stimulation of the hand and knee.

RESULTS

Patients with and without pain and with and without inflammation (joint and systemic) were evaluated.  Pain severity was associated with more physical stress and poorer cognitive function. Corrected for multiple comparisons, morphological analysis revealed decreased cortical thickness within the insula cortex and a negative correlation between caudate nucleus volume and pain severity. Functional neuroimaging findings suggested alteration within neurocircuitry structures regulating emotional pain processing (anterior insula) in addition to the default-mode and sensorimotor networks.

CONCLUSIONS

Patients with JIA may exhibit changes in neurobiological circuits related to pain. These preliminary findings suggest mechanisms by which pain could potentially become dissociated from detectable joint pathology and persist independently of inflammation or treatment status.

Left to themselves: Time to target chronic pain in childhood rare diseases

BACKGROUND

Chronic pain is prevalent among patients with rare diseases (RDs). However, little is understood about how biopsychosocial mechanisms may be integrated in the unique set of clinical features and therapeutic challenges inherent in their pain conditions.

METHODS

This review presents examples of major categories of RDs with particular pain conditions. In addition, we provide translational evidence on clinical and scientific rationale for psychosocially- and neurodevelopmentally-informed treatment of pain in RD patients.

RESULTS

Neurobiological and functional overlap between various RD syndromes and pain states suggests amalgamation and mutual modulation of the respective conditions. Emotional sequelae could be construed as an emotional homologue of physical pain mediated via overlapping brain circuitry. Given their clearly defined genetic and molecular etiologies, RDs may serve as heuristic models for unraveling pathophysiological processes inherent in chronic pain.

CONCLUSIONS

Systematic evaluation of chronic pain in patients with RD contributes to sophisticated insight into both pain and their psychosocial correlates, which could transform treatment.

Recent progress in the treatment of non-systemic juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is a chronic inflammatory disease affecting the joints and other organs that occurs in 1 in 1,000 children in the United States. Given the various categories of JIA, interpretation of the literature can be difficult. In this review, new developments in understanding non-systemic JIA and its treatment will be covered. Recent advances in the journey toward personalized treatment in JIA will be highlighted, including a review of currently available biologic modifiers. Uveitis and the temporomandibular joint will be discussed as particularly challenging treatment issues. Recent guideline updates and literature-guided treatment decisions will be reviewed.

[Rheumatic pain and chronic pain in children, adolescents and young adults]

BACKGROUND

Rheumatic diseases, such as juvenile idiopathic arthritis (JIA), are typically associated with acute pain mainly caused by inflammation. Chronic pain is described as pain lasting at least 3 months. In JIA patients chronic pain may occur despite successful treatment. Chronic pain and pain disorders frequently occur during the course of the disease despite successful control of inflammation.

OBJECTIVE

Possible interrelations between JIA and pain disorders are presented.

METHOD

Besides a review of the available literature, a retrospective cohort study was conducted, including 906 patients with a chronic pain disorder with somatic and psychological factors (CPD) and/or a complex regional pain syndrome type I (CRPS I). The frequency of pre-existing rheumatic illnesses was analyzed.

RESULTS

The JIA is a risk factor for the development of a CPD. Especially polyarticular, extended oligoarticular, enthesitis-associated JIA and psoriatic arthropathy were found to be significantly associated with an increased risk for developing CPD. In contrast, an increased risk for development of CRPS I was not observed.

CONCLUSION

Our study demonstrates JIA to be a risk factor for the development of chronic pain not only as a result from malpositioning or arthrosis but also as a chronic pain disorder (CPD). Further studies are necessary to clarify the relevance of disease activity and duration and also of psychological factors for the pathogenesis.

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.

Initiating disease-modifying anti-rheumatic drugs rapidly reduces purchases of analgesic drugs in juvenile idiopathic arthritis

Objective: To describe the use of analgesics 12 months before and after initiation of the first disease-modifying anti-rheumatic drug (DMARD) in children with juvenile idiopathic arthritis (JIA). Method: A register-based study linked three nationwide registers in Finland: the Register on Reimbursement for Prescription Medicines, the Drug Purchase Register (both maintained by the Finnish Social Insurance Institution), and the Finnish Population Register. The study ran from 1 January 2010 to 31 December 2014. It included 1481 patients aged < 16 years with diagnosed JIA and 4511 matched controls. Index day was the date when reimbursement for JIA medication was approved and treatment was initiated. The study period included 12 months pre- and post-index date, and purchases of prescription drugs were assessed for 3 month periods. Results: Non-steroidal anti-inflammatory drugs (NSAIDs) were purchased for 60% of the patients. Compared to controls, NSAID purchases for JIA patients were at their highest during the last 3 months before the index day [relative rate (RR) 21.2, 95% confidence interval (CI) 17.1-26.2], and they decreased steeply over the 10-12 months post-index (RR 4.0, 95% CI 3.1-5.0). Similar trends were seen with paracetamol and opioid purchases, but only 2% of patients purchased opioids during the 12 months pre-index and 1% during the 12 months post-index. Methotrexate was the most commonly used DMARD (91.9%), biologic DMARDs were used by 2.8% and glucocorticoids by 24.8% in the 3 months after the index day. Conclusion: Initiation of DMARDs rapidly reduces the need for analgesics in patients with JIA.

The pain trajectory of juvenile idiopathic arthritis (JIA): translating from adolescent patient report to behavioural sensitivity in a juvenile animal model

BACKGROUND

While pain is a common symptom in JIA patients, it remains unclear why some JIA patients develop ongoing or persistent pain. Complex clinical and social settings confound analysis of individual factors that may contribute to this pain. To address this, we first undertook a retrospective analysis of pain reports in a JIA patient cohort with the aim of identifying potential factors contributing to persistent pain. We then carried out an experimental laboratory study, using joint inflammatory pain behaviour in rodents, to validate the role of these factors in the onset of persistent pain under controlled conditions.

METHODS

Patients: Retrospective analysis of anonymised pain visual analogue scale (VAS) scores and accompanying clinical scores from 97 JIA patients aged 13-19 (mean: 16.40 ± 1.21) collected over 50 weeks. Rats: Experimental study of pain behaviour following intra-articular microinjection of complete Freund's adjuvant (CFA) in adolescents (n = 25) and young adults (n = 43). Some animals (n = 21) had been previously exposed to joint inflammation in infancy or adolescence.

RESULTS

Patients: Cluster analysis of patient pain VAS scores revealed three trajectories over 50 weeks: consistently low pain (n = 45), variable pain (n = 30) and persistently high pain (n = 22). Number of actively inflamed joints did not differ in the three groups. High pain at a single visit correlated with greater physician global assessment of disease activity, while a high pain trajectory over 50 weeks was associated with more limited joints but fewer actively inflamed joints. Rats: Rodents administered ankle joint CFA also exhibit low, medium and high joint pain sensitivities, independent of joint inflammation. Prolonged inflammatory pain behaviour was associated with high background pain sensitivity, following joint inflammation at an earlier stage in life.

CONCLUSIONS

Both JIA patients and rodents differ in their individual pain sensitivity independent of the concurrent joint inflammation. Using experimental animal models allows us to isolate physiological factors underlying these differences, independently of social or clinical factors. The results suggest that a history of prior arthritic activity/joint inflammation may contribute to high pain sensitivity in adolescents with JIA.

Longitudinal Evaluation of Pain, Flare-Up, and Emotional Health in Fibrodysplasia Ossificans Progressiva: Analyses of the International FOP Registry

Fibrodysplasia ossificans progressiva (FOP) is an ultra‐rare, inherited, connective tissue disease with ∼800 documented cases worldwide. The principal pathological feature of FOP is the transition of skeletal muscle, tendons, ligaments, and fascia into cartilage and bone. This heterotopic ossification (HO) is often preceded by painful soft tissue swellings or flare‐ups that may last several months. For many individuals, experiencing a flare‐up may represent a worsening of their condition and contribute to feelings of anxiety or suppressed affect, both of which are well‐recognized to exacerbate pain perception. To date, much remains unknown regarding the dynamics of pain and emotional health in FOP during flare‐up and also quiescent, non–flare‐up disease phases. In order to elucidate the occurrence and effect of pain in FOP, this study analyzed Patient‐Reported Outcomes Measurement Information System–based questionnaires completed by 99 patients participating in the international FOP Registry over a 30‐month period. We observed that although moderate to severe pain (≥4, 0 to 10 pain scale) was commonly associated with flare‐ups (56% to 67%), surprisingly, 30% to 55% of patients experienced similar pain levels during non–flare‐up states. In those patients reporting pain levels of ≥4, 45% to 74% of patients report experiencing anxiety, depression, or irritability, with 36% to 48% reporting emotional problems during no to mild pain states. Furthermore, independent of the flare‐up status, the severity of pain in FOP patients was found to be significantly anti‐correlated with emotional health, physical health, and overall quality‐of‐life. These findings strongly suggest the need for an improved understanding of pain and emotional health in FOP during flare‐up and quiescent periods. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.