Abnormalities in skeletal growth in children with juvenile rheumatoid arthritis

Expert panel consensus recommendations for diagnosis and treatment of secondary osteoporosis in children

BACKGROUND

Osteoporosis incidence in children is increasing due to the increased survival rate of patients suffering from chronic diseases and the increased use of drugs that can damage bones. Recent changes made to the definition of childhood osteoporosis, along with the lack of guidelines or national consensuses regarding its diagnosis and treatment, have resulted in a wide variability in the approaches used to treat this disease. For these reasons, the Osteogenesis Imperfecta and Childhood Osteoporosis Working Group of the Spanish Society of Pediatric Rheumatology has sounded the need for developing guidelines to standardize clinical practice with regard to this pathology.

METHODS

An expert panel comprised of 6 pediatricians and 5 rheumatologists carried out a qualitative literature review and provided recommendations based on evidence, when that was available, or on their own experience. The level of evidence was determined for each section using the Oxford Centre for Evidence-based Medicine (CEBM) system. A Delphi survey was conducted for those recommendations with an evidence level of IV or V. This survey was sent to all members of the SERPE. All recommendations that had a level of agreement higher or equal to 70% were included.

RESULTS

Fifty-one recommendations, categorized into eight sections, were obtained. Twenty-four of them presented an evidence level 4 or 5, and therefore a Delphi survey was conducted. This was submitted electronically and received a response rate of 40%. All recommendations submitted to the Delphi round obtained a level of agreement of 70% or higher and were therefore accepted.

CONCLUSION

In summary, we present herein guidelines for the prevention, diagnosis and treatment of secondary childhood osteoporosis based on the available evidence and expert clinical experience. We believe it can serve as a useful tool that will contribute to the standardization of clinical practice for this pathology. Prophylactic measures, early diagnosis and a proper therapeutic approach are essential to improving bone health, not only in children and adolescents, but also in the adults they will become in the future.

General Nutrition and Fitness for the Child with Rheumatic Disease

As a result of new medications and therapeutic approaches, most children with rheumatic diseases are no longer at risk for growth failure which results from chronic inflammation and prolonged corticosteroid treatment. However, obesity, poor nutrition, and insufficient exercise are still problems which increase risks for poor bone, cardiovascular, and general health. Diet should be monitored and modified as appropriate; supplemental calcium and Vitamin D should be provided. Obesity and poor physical fitness can be ameliorated by an exercise program that should become part of a more healthy lifestyle.

Protecting Bone Health in Pediatric Rheumatic Diseases: Pharmacological Considerations

Bone health in children with rheumatic conditions may be compromised due to several factors related to the inflammatory disease state, delayed puberty, altered life style, including decreased physical activities, sun avoidance, suboptimal calcium and vitamin D intake, and medical treatments, mainly glucocorticoids and possibly some disease-modifying anti-rheumatic drugs. Low bone density or even fragility fractures could be asymptomatic; therefore, children with diseases of high inflammatory load, such as systemic onset juvenile idiopathic arthritis, juvenile dermatomyositis, systemic lupus erythematosus, and those requiring chronic glucocorticoids may benefit from routine screening of bone health. Most commonly used assessment tools are laboratory testing including serum 25-OH-vitamin D measurement and bone mineral density measurement by a variety of methods, dual-energy X-ray absorptiometry as the most widely used. Early disease control, use of steroid-sparing medications such as disease-modifying anti-rheumatic drugs and biologics, supplemental vitamin D and calcium, and promotion of weight-bearing physical activities can help optimize bone health. Additional treatment options for osteoporosis such as bisphosphonates are still controversial in children with chronic rheumatic diseases, especially those with decreased bone density without fragility fractures. This article reviews common risk factors leading to compromised bone health in children with chronic rheumatic diseases and discusses the general approach to prevention and treatment of bone fragility.

Friends United: An Evaluation of an Innovative Residential Self-Management Programme in Adolescent Rheumatology

Independence in activities of daily living, self-advocacy and peer support are important aspects of adolescent development. These skills are potentially affected by chronic rheumatic diseases and are worthy of attention by occupational therapists and other members of the multidisciplinary team.

An innovative 4-day residential programme for young people diagnosed with chronic rheumatic disease, known as the ‘Independence Break’, was evaluated in order to determine its perceived benefits. The participants were invited to complete a brief evaluation form immediately after the trip to determine the benefits of participation in the programme. The levels of continuing social contact within the group were established 4 months later during a subsequent telephone call.

Thirty young people (median age 14 years) attended the 4-day programme and reported friendship and improved performance in activities of daily living as the major benefits. The majority stayed in touch with at least one other person, with more girls staying in touch than boys. The preferred method of communication was text messaging.

Overall, the programme was perceived to be a valuable experience and offered the young people an opportunity to develop informal peer support networks. The potential of text messaging within adolescent rheumatology is also highlighted.

Impact of local steroid or statin treatment of experimental temporomandibular joint arthritis on bone growth in young rats

INTRODUCTION

Juvenile idiopathic arthritis in temporomandibular joints (TMJs) is often treated with intra-articular steroid injections, which can inhibit condylar growth. The purpose of this study was to compare simvastatin (a cholesterol-lowering drug that reduces TMJ inflammation) with the steroid triamcinolone hexacetonide in experimental TMJ arthritis.

METHODS

Joint inflammation was induced by injecting complete Freund's adjuvant (CFA) into the TMJs of 40 growing Sprague Dawley rats; 4 other rats were left untreated. In the same intra-articular injection, one of the following was applied: (1) 0.5 mg of simvastatin in ethanol carrier, (2) ethanol carrier alone, (3) 0.15 mg of triamcinolone hexacetonide, (4) 0.5 mg of simvastatin and 0.15 mg of triamcinolone hexacetonide, or (5) nothing additional to the CFA. The animals were killed 28 days later, and their mandibles were evaluated morphometrically and with microcomputed tomography.

RESULTS

The analysis showed that the TMJs subjected to CFA alone had decreased ramus height compared with those with no treatment (P <0.05). Groups that had injections containing the steroid overall had decreases in weight, ramus height, and bone surface density when compared with the CFA-alone group (P <0.0001). Groups that had injections containing simvastatin, however, had overall increases in weight (P <0.0001), ramus height (P <0.0001), condylar width (P <0.05), condylar bone surface density (P <0.05), and bone volume (P <0.0001) compared with the groups receiving the steroid injections, and they were not different from the healthy (no treatment) group.

CONCLUSIONS

Treatment of experimentally induced arthritis in TMJs with intra-articular simvastatin preserved normal condylar bone growth.

Glucocorticoid-associated osteoporosis in chronic inflammatory diseases: epidemiology, mechanisms, diagnosis, and treatment

Children with chronic illnesses such as Juvenile Idiopathic Arthritis and Crohn's disease, particularly when taking glucocorticoids, are at significant risk for bone fragility. Furthermore, when childhood illness interferes with achieving normal peak bone mass, life-long fracture risk is increased. Osteopenia and osteoporosis, which is increasingly recognized in pediatric chronic disease, likely results from numerous disease- and treatment-related factors, including glucocorticoid exposure. Diagnosing osteoporosis in childhood is complicated by the limitations of current noninvasive techniques such as DXA, which despite its limitations remains the gold standard. The risk:benefit ratio of treatment is confounded by the potential for spontaneous restitution of bone mass deficits and reshaping of previously fractured vertebral bodies. Bisphosphonates have been used to treat secondary osteoporosis in children, but limited experience and potential long-term toxicity warrant caution in routine use. This article reviews the factors that influence loss of normal bone strength and evidence for effective treatments, in particular in patients with gastrointestinal and rheumatologic disorders who are receiving chronic glucocorticoid therapy.

Automated determination of bone age and bone mineral density in patients with juvenile idiopathic arthritis: a feasibility study

Introduction

Chronic inflammation combined with glucocorticoid treatment and immobilization puts juvenile idiopathic arthritis (JIA) patients at risk of impaired growth and reduced bone mineral density (BMD). Conventional methods for evaluating bone age and BMD are time-consuming or come with additional costs and radiation exposure. In addition, an automated measurement of bone age and BMD is likely to be more consistent than visual evaluation. In this study, we aimed to evaluate the feasibility of an automated method for determination of bone age and (cortical) bone mineral density (cBMD) in severely affected JIA patients. A secondary objective was to describe bone age and cBMD in this specific JIA population eligible for biologic treatment.

Methods

In total, 69 patients with standard hand radiographs at the start of etanercept treatment and of calendar age within the reliability ranges (2.5 to 17 years for boys and 2 to 15 years for girls) were extracted from the Dutch Arthritis and Biologicals in Children register. Radiographs were analyzed using the BoneXpert method, thus automatically determining bone age and cBMD expressed as bone health index (BHI). Agreement between measurements of the left- and right-hand radiographs and a repeated measurement of the left hand were assessed with the intraclass correlation coefficient (ICC). Regression analysis was used to identify variables associated with Z-scores of bone age and BHI.

Results

The BoneXpert method was reliable in the evaluation of radiographs of 67 patients (radiographs of 2 patients were rejected because of poor image quality). Agreement between left- and right-hand radiographs (ICC = 0.838 to 0.996) and repeated measurements (ICC = 0.999 to 1.000) was good. Mean Z-scores of bone age (−0.36, P = 0.051) and BHI (−0.85, P < 0.001) were lower compared to the healthy population. Glucocorticoid use was associated with delayed bone age (0.79 standard deviation (SD), P = 0.028), and male gender was associated with a lower Z-score of BHI (0.65 SD, P = 0.021).

Conclusions

BoneXpert is an easy-to-use method for assessing bone age and cBMD in patients with JIA, provided that radiographs are of reasonable quality and patients’ bone age lies within the age ranges of the program. The population investigated had delayed bone maturation and lower cBMD than healthy children.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0424-1) contains supplementary material, which is available to authorized users.

An experimental therapy to improve skeletal growth and prevent bone loss in a mouse model overexpressing IL-6

Premature osteoporosis and stunted growth are common complications of childhood chronic inflammatory disease. Presently, no treatment regimens are available for these defects in juvenile diseases. We identified the sequential Fc-OPG/hPTH treatment as an experimental therapy that improves the skeletal growth and prevents the bone loss in a mouse model overexpressing IL-6.

INTRODUCTION

Premature osteoporosis and stunted growth are common complications of childhood chronic inflammatory diseases and have a significant impact on patients' quality of life. Presently, no treatment regimens are available for these defects in juvenile diseases. To test a new therapeutic approach, we used growing mice overexpressing the pro-inflammatory cytokine IL-6 (TG), which show a generalized bone loss and stunted growth.

METHODS

Since TG mice present increased bone resorption and impaired bone formation, we tested a combined therapy with the antiresorptive modified osteoprotegerin, Fc-OPG, and the anabolic PTH. We injected TG mice with Fc-OPG once at the 4th day of life and with hPTH(1-34) everyday from the 16th to the 30th day of age.

RESULTS

A complete prevention of growth and bone defects was observed in treated mice due to normalization of osteoclast and osteoblast parameters. Re-establishment of normal bone turnover was confirmed by RT-PCR analysis and by in vitro experiments that revealed the full rescue of osteoclast and osteoblast functions. The phenotypic recovery of TG mice was due to the sequential treatment, because TG mice treated with Fc-OPG or hPTH alone showed an increase of body weight, tibia length, and bone volume to intermediate levels between those observed in vehicle-treated WT and TG mice.

CONCLUSIONS

Our results identified the sequential Fc-OPG/hPTH treatment as an experimental therapy that improves the skeletal growth and prevents the bone loss in IL-6 overexpressing mice, thus providing the proof of principle for a therapeutic approach to correct these defects in juvenile inflammatory diseases.

Coordination of organ growth: principles and outstanding questions from the world of insects

In animal species undergoing determinate growth, the making of a full-size adult body requires a series of coordinated growth events culminating in the cessation of growth that precedes sexual maturation. The merger between physiology and genetics now coming to pass in the Drosophila model allows us to decipher these growth events with an unsurpassed level of sophistication. Here, we review several coordination mechanisms that represent fundamental aspects of growth control: adaptation of growth to environmental cues, interorgan coordination, and the coordination of growth with developmental transitions. The view is emerging of an integrated process where organ-autonomous growth is coordinated with both developmental and environmental cues to define final body size.

Drosophila growth and development: keeping things in proportion

Comment on: Colombani J, et al. Science 2012; 336:582-5.

Mechanisms of growth impairment in pediatric Crohn's disease

Crohn's disease manifests during childhood or adolescence in up to 25% of patients. The potential for linear growth impairment as a complication of chronic intestinal inflammation is unique to pediatric patient populations. Insulin-like growth factor I (IGF-I), produced by the liver in response to growth hormone (GH) stimulation, is the key mediator of GH effects at the growth plate of bones. An association between impaired growth in children with Crohn's disease and low IGF-I levels is well recognized. Early studies emphasized the role of malnutrition in suppression of IGF-I production. However, a simple nutritional hypothesis fails to explain all the observations related to growth in children with Crohn's disease. The direct, growth-inhibitory effects of proinflammatory cytokines are increasingly recognized and explored. The potential role of noncytokine factors, such as lipopolysaccharides, and their potential to negatively influence the growth axis have recently been investigated with intriguing results. There is now reason for optimism that the modern anticytokine therapeutic agents available for treating children and adolescents with Crohn's disease will reduce the prevalence of this otherwise common complication. As our understanding of the mechanisms that underlie growth impairment advance, so too should the opportunity for developing further novel and targeted therapies.

Growth and bone mineralization in patients with juvenile idiopathic arthritis

OBJECTIVE

To investigate growth, development and bone mineralization of children with juvenile idiopathic arthritis (JIA).

METHODS

Thirty patients between 4-17 years of age (mean 11.34 +/- 3.88) resistant to therapy were studied. Enrollment began in November 1999 and continued through November 2004 and children with chronic disease were excluded. Data like height, weight, medications and acute phase reactants were obtained from medical records. On study-visit, puberty was assessed by physical examination and bone mineral density (BMD) was measured. Serum Ca, P, ALP, insulin-like growth factor-1 (IGF-1) and urinary Ca/Cr and hydroxyproline /Cr levels were measured. Results were compared with the control group that consisted of 30 cases of similar age and gender.

RESULTS

Patients with JIA had decreased height standard deviation score (SDS) and growth retardation. BMD of the cases in the study group was lower than the control group (p< 0.05). Patients who were at younger age at the onset of the disease had lower BMD. Among the drugs, only steroids had a negative effect on growth. Serum IGF-1 levels of the study group were significantly lower than the control group (p< 0.0001).

CONCLUSION

Early diagnosis and suppression of disease activity is important in prevention of osteoporosis and growth retardation in children with JIA. BMD has to be measured yearly in patients for accurate diagnosis of osteoporosis. Vitamin D and Ca-rich nutrition with promotion of physical activity and controlled use of steroids may protect the children against bone loss.

Bone mineral density in children wth systemic lupus erythematosus and juvenile rheumatoid arthritis

BACKGROUND

Although there is increasing in bone metabolism in patients with rheumatic disorders, few data exist on bone mineral density (BMD) in children with rheumatic disorders or on the association of BMD with disease-related variables. We determined BMD in Iranian children with systemic lupus erythematosus (SLE) and juvenile rheumatoid arthritis (JRA) to evaluate the relationship between disease-related variables and BMD.

PATIENTS AND METHODS

Twenty patients (13 girls and 7 boys) with SLE (n=15) and JRA (n=5) with a mean age of 13.10+/-3.29 years (range, 6-17 years), attending a pediatric rheumatology clinic and 20 healthy controls (matched for age and sex with each patient) were enrolled in a cross-sectional study between 2001 and 2003. BMD (g/cm(2)) of the femoral neck (BMD-F) and lumbar vertebrae (BMD-L) were measured by dual energy X-ray absorptiometry (DEXA). The correlation between BMD and cumulative dose of steroids, daily dose of steroid, disease duration, disease activity, height, weight, and age was investigated.

RESULTS

BMD in the patients (BMD-F=0.72+/-0.15, BMD-L=0.70+/-0.19) was significantly lower than controls (BMD-F=0.95+/-0.17, BMD-L=0.98+/-0.20, P=<0.001). The severity of descreased BMD was more prominent in lumbar vertebrae than the femoral neck (P=0.04). None of the variables were consistently related to a decrease in BMD.

CONCLUSION

BMD was significantly lower in patients compared with controls. It was more prominent in lumbar vertebrae (trabecular bone). Although cumulative dose of steroids and diseaese appeared to have some influence on BMD, none were independently correlated with BMD.

Can exercise influence low bone mineral density in children with juvenile rheumatoid arthritis?

PURPOSE

Low bone mineral density (BMD) is a common secondary condition associated with juvenile idiopathic arthritis (JIA). The purpose of this review was evaluate the literature pertinent to designing an effective, safe weight-bearing exercise program to reduce the risk of low BMD in children with JIA.

SUMMARY OF KEY POINTS

Thirty-seven articles on the risk of low BMD and children with JIA, weight-bearing interventions to improve BMD in healthy children, or safety and efficacy of exercise interventions with children with JIA were critiqued on the basis of their design. Three highly rated studies confirmed the multifactorial nature of low BMD in children with JIA, two highly rated studies support the efficacy of weight-bearing interventions for increasing BMD in children who are healthy, and one moderately rated study demonstrated the safety of low impact exercise by children with JIA.

STATEMENT OF CONCLUSIONS AND RECOMMENDATIONS FOR CLINICAL PRACTICE

Weight-bearing activities should be included in exercise programs for individuals with JIA, although more research is needed to determine the amount, duration, and frequency of weight-bearing activity needed to reduce the risk for low BMD.

Impaired skeletal development in interleukin-6-transgenic mice: a model for the impact of chronic inflammation on the growing skeletal system

OBJECTIVE

To identify the mediator responsible for the impact of chronic inflammation on skeletal development in children (bone loss, defective peak bone mass accrual, stunted growth), we evaluated the effects of chronic interleukin-6 (IL-6) overexpression on the skeletons of growing prepubertal mice.

METHODS

We studied IL-6-transgenic mice that had high circulating IL-6 levels since birth. Trabecular and cortical bone structure were analyzed by microcomputed tomography. Epiphyseal ossification, growth plates, and calvariae were studied by histology/histomorphometry. Osteoclastogenesis, osteoblast function/differentiation, and the effects of IL-6 on bone cells were studied in vitro. Osteoblast gene expression was evaluated by reverse transcriptase-polymerase chain reaction. The mineral apposition rate was evaluated dynamically in cortical bone by in vivo double fluorescence labeling.

RESULTS

In prepubertal IL-6-transgenic mice, we observed osteopenia, with severe alterations in cortical and trabecular bone microarchitecture, as well as uncoupling of bone formation from resorption, with decreased osteoblast and increased osteoclast number and activity. Increased osteoclastogenesis and reduced osteoblast activity, secondary to decreased precursor proliferation and osteoblast function, were present. IL-6-transgenic mice also showed impaired development of growth plates and epiphyseal ossification centers. Intramembranous and endochondral ossification and the mineral apposition rate were markedly affected, showing the presence of defective ossification.

CONCLUSION

Chronic overexpression of IL-6 alone induces a skeletal phenotype closely resembling growth and skeletal abnormalities observed in children with chronic inflammatory diseases, pointing to IL-6 as a pivotal mediator of the impact of chronic inflammation on postnatal skeletal development. We hypothesize that IL-6-modifying drugs may reduce skeletal defects and prevent the growth retardation associated with these diseases.

Principles of management of musculoskeletal conditions in children and young people

Musculoskeletal symptoms and rheumatic conditions are common throughout childhood and adolescence. Age- and development-appropriate care and management of children and young people with such conditions is vital, acknowledging that they are NOT small adults! The major aspect of both paediatric and adolescent rheumatology care which differentiates it from adult care is the fact that children and young people are still growing, in contrast to the ageing and senescence which characterizes adult rheumatology. Growth must be considered in the global sense, incorporating cognitive and psychosocial growth as well as physical growth. Likewise, the reciprocal influences of growth and a chronic rheumatic condition should be considered when caring for young people with childhood-onset rheumatic disease. This chapter will detail the general principles of management of such symptomatology with primary reference to chronic conditions.

[Diagnosis and treatment of juvenile osteoporosis]

Bone mass is primarily genetically determined, but exogenous factors also play a major role. The prevention of osteoporosis can start from childhood, and optimal achievement of peak bone mass during childhood and adolescence is important in order to minimise future fracture risks. Chronic inflammatory diseases can have a detrimental effect on bone mass, by means of several mechanisms. Different diagnostic methods for detection and monitoring of osteoporosis are in use or under investigation. The role of calcium and vitamin D supplementation for the prevention and treatment of osteoporosis associated with paediatric rheumatic diseases remains to be established. New treatments such as bisphosphonates and calcitonin are now available, although their use in the paediatric age has been limited.

Prevention of Osteoporosis: A Randomized Clinical Trial to Increase Calcium Intake in Children with Juvenile Rheumatoid Arthritis

OBJECTIVE

To test the efficacy of a behavioral intervention (BI) compared to an enhanced standard of care (ESC) dietary counseling on increasing dietary calcium (Ca) intake in children with juvenile rheumatoid arthritis (JRA).

METHODS

Three-day food diaries collected at baseline and posttreatment were analyzed for Ca intake in 49 children with JRA randomly assigned to either BI or an ESC treatment.

RESULTS

Children in the BI (N = 25) demonstrated a significantly greater increase in average dietary Ca intake (M = 839) than children in the ESC (N = 24; M = 420) (F = 14.39; p < .001). Post hoc analysis revealed that children in both groups demonstrated significant gains in dietary Ca intake baseline to posttreatment. A significantly greater percentage of children in the BI (92%) attained the goal of 1500 mg/Ca at posttreatment compared to the ESC (17%), X2= 28.09; p < .001.

CONCLUSIONS

Behavioral intervention can have a positive impact on increasing dietary Ca intake. Future research will need to evaluate the maintenance of gains in dietary Ca intake following treatment cessation and the impact of increased Ca intake on bone mineral density.

Infusionstherapie und Ernährung von Risikogruppen

Besondere Situationen erfordern ein besonderes Vorgehen. Während bisher das »Standardvorgehen« bezüglich der Ernährung von pädiatrischen Patienten dargestellt wurde, beschäftigt sich das vorliegende Kapitel mit »Sondersituationen« der pädiatrischen Infusionstherapie und Ernährung. Behandlungssituationen, die ein besonderes Vorgehen bei der Therapie oder spezielle Aufmerksamkeit bei der Anpassung der Ernährung erfordern, entstehen in der Regel durch 4 mögliche Situationen:

spezifische Physiologie von Patientengruppen (z. B. Früh- oder Neugeborene),

Auswirkungen von therapeutischen Maßnahmen (z. B. Operationen),

Pathophysiologie von Erkrankungen (z. B. angeborene Stoffwechselerkrankungen, Erkrankungen des onkologischen, rheumatischen oder atopischen Formenkreises, Anorexia nervosa, Bulimie oder Adipositas) oder

besondere körperliche Belastungen [z. B. (Leistungs-)Sport].

Bekannte Strategien werden systematisch und prägnant dargestellt und diskutiert.

Die Beschäftigung mit der Ernährung von »Risikogruppen« übt das Erkennen und den Umgang von potenziellen Gefahrensituationen bei der Verordnung von bilanzierter Ernährung. So sollte auch derjenige von dem Kapitel profitieren, der sich mit den behandelten Patientengruppen, Situationen, Erkrankungen üblicherweise nicht beschäftigen muss.

[Growth in children with juvenile idiopathic arthritis]

INTRODUCTION

Juvenile idiopathic arthritis (JIA) is a chronic inflammatory disease that often requires steroid therapy. Growth retardation can be a serious complication in some of these patients.

OBJECTIVE

To study linear growth in patients with JIA and evaluate the factors involved in its disturbance.

METHODS

We studied 91 patients with JIA with a follow-up of at least one year. A cross sectional study, a longitudinal retrospective study, and a longitudinal prospective study were performed. Height in the first consultation, in the cross sectional study, and one year previously was evaluated. Height velocity (HV) was calculated. Several parameters related to disease activity, corticosteroid therapy, nutritional and hormonal status, and bone mineral density (BMD) were analyzed. A correlation study and multivariate regression analysis were carried out.

RESULTS

Height was < or = -2 SD in 14.3 % of the series and in 55.6 % of the systemic group. Variables independently associated with height were total corticosteroid dose, functional class, nutritional index, BMD, and age at onset of the disease. HV was < or = 2 SD in 25.3 % of the series and in 61 % of the systemic group. Variables independently associated with HV were corticosteroid dose and the number of swollen joints.

CONCLUSIONS

Growth retardation in patients with JIA was associated with factors related to the disease, corticosteroid therapy, nutritional status, BMD, and earlier onset of the disease.

Treatment of rheumatic diseases in children: special considerations

The goals of treatment of rheumatic diseases in children are to control the disease process while ensuring normal nutrition, growth, and development. The choice of antirheumatic drugs is similar in children and adults, but the doses, treatment schedules, and susceptibility to toxicity can differ considerably. In addition to differences between adult and pediatric diseases themselves, it is important for the rheumatologist who treats children to be cognizant of the impact of nutritional, developmental, and growth issues and differential susceptibility to toxicity of various treatments.

Osteoporosis in juvenile idiopathic arthritis

Osteoporosis is characterized by loss of both bone mass and microarchitectural integrity, resulting in an increased risk of fractures with associated morbidity and mortality. Awareness of this condition is increasing in pediatrics, including pediatric rheumatology. Reduced bone mineral density is now well recognized in children and young adults with juvenile idiopathic arthritis and is multifactorial in origin. The problems of interpretation of bone analysis techniques during childhood and adolescence are highlighted. Recent studies have reported on the use of newer methods of imaging, including quantitative ultrasound and bone single photon emission computed tomography techniques. Attempting to disentangle the relative effects of disease activity, corticosteroids, nutrition, and physical activity in the development of osteoporosis in juvenile idiopathic arthritis is the focus of several studies. Finally, early optimistic reports of the use of bisphosphonates in juvenile idiopathic arthritis are welcome additions to the growing body of literature in this area.

The treatment of juvenile arthritis

Until recently, two different classification systems for juvenile arthritis (JA) were utilised, each with its own terminology and subclassification. It has been recognised that particularly within the polyarticular and pauciarticular groups, many distinct subsets exist each with a different prognosis. As a result, a new classification system for JA has been developed. It is hoped that this will allow more accurate assessment of incidence and aetiology of the various subtypes in future generations and in time will allow therapy to be targeted at those most likely to achieve benefit. Since there is a new classification system for JA, the vast majority of published clinical studies were performed using the old classification system. For the purposes of this review, unless otherwise stated, the American College of Rheumatology classification will be used. This is outlined in Table 1 with clinical features of the major subtypes described in Table 3. This review will cover current best practice and discuss future directions for research using the recent advances in the treatment of rheumatoid arthritis (RA) as a model.

Young adults with juvenile arthritis in remission attain normal peak bone mass at the lumbar spine and forearm

OBJECTIVE

To assess the impact of disease activity on acquired peak bone mass and bone turnover in young adult patients with either persistent juvenile arthritis (JA) or a history of JA (JA in remission).

METHODS

Two hundred twenty-nine patients with JA were studied after a mean +/- SD of 15.6 +/- 2.4 years in women and 14.9 +/- 2.1 years in men since disease onset. One hundred forty-five women and 84 men were over the age of 20 at the time of examination (mean +/- SD age 24.9 +/- 2.9 years for women and 25.2 +/- 3.1 years for men). Forty-one healthy women (mean +/- SD age 27.4 +/- 3.1 years) and 55 healthy men (mean +/- SD age 25.7 +/- 3.1 years) served as a reference group. Bone mineral density (BMD) was analyzed by dual x-ray absorptiometry. Serum osteocalcin concentrations and urinary concentrations of deoxypyridium (D-Pyd) were measured. Linear regression analyses were performed to evaluate the impact of disease on BMD.

RESULTS

Patients with persistent disease had significantly lower BMD compared with healthy subjects (P < 0.001 for women at all measured sites and for men at the femoral neck and total body; P < 0.05 for men at the radius and lumbar spine). Of the patients with a history of JA, only women had significantly lower BMD at the femoral neck and total body (P < 0.05). Patients with persistent JA had significantly more osteopenia and osteoporosis than healthy subjects, while patients with a history of JA had more frequent osteopenia only in the total body. Weight, urinary concentration of D-Pyd, and belonging to the patient group significantly affected BMD at all measured sites in the entire study population, while analysis of all patients found that only the number of months taking corticosteroids significantly affected BMD at all measured sites. However, the impact of the variables differed from site to site.

CONCLUSION

Our findings imply that most young adults with JA attain the same BMD as healthy subjects if the disease goes into remission, while young adults with active disease have increased risk for osteopenia and osteoporosis.

Osteoporosis: a new challenge in cystic fibrosis

The increased life expectancy of patients with cystic fibrosis (CF) may lead to medical complications such as osteoporosis. Based on data collected through a MEDLINE search (1985-May 1999) and review of references for additional relevant articles, nutrition status, weight, and disease severity are factors most highly correlated with osteopenia. Links also were noted with calcium and vitamin D intake, hypogonadism, chronic inflammation, and age, but findings in these areas are not consistent from one report to the next. Increased fracture rates and kyphosis are consequences of osteoporosis. Simple measures such as compliance with recommended nutrition guidelines and restrictions in corticosteroid therapy could be considered first-line management options. Further studies must be conducted to clarify factors involved in the etiology of osteoporosis in patients with CF and to identify the best treatment and prevention methods.

Use of quantitative ultrasound to assess bone status in children with juvenile idiopathic arthritis: a pilot study

Periarticular osteoporosis around inflammed joints and generalized osteoporosis have been shown to be markers of disease activity and severity in children with juvenile idiopathic arthritis (JIA). Bone mineral density (BMD) in adults can be assessed precisely by dual X-ray absorptiometry (DXA), but this technique has not been used widely in children. Quantitative ultrasound (QUS) may provide an alternative method for assessment of bone status. The aim of this pilot study was to compare QUS to DXA in assessing generalized osteoporosis in a cohort of patients JIA. Twenty-two Caucasian children (15 females, 7 males) with JIA of duration 19-142 months (mean 71 mo) and age 7-17 yr were recruited. Total body and lumbar spine BMD and bone mineral content (BMC) were measured by DXA using standard procedures on a Lunar DPX-L scanner. QUS was performed using Myriad SoundScan 2000. Speed of sound (SOS) was measured at the right midtibia. The DXA results were compared to QUS using linear regression analysis. Spine and total body BMD measured by DXA correlated significantly with tibia SOS (spine: r = 0.57, p < 0.007; total body: r = 0.68, p < 0.001). Spine BMC was similarly related to SOS as BMD (r = 0.58, p < 0.007). Individual patient weight and height were strong predictors of BMD, but only moderate predictors of SOS. The mean spine BMD was lower in the JIA patients compared to the normal ranges (mean Z-score of -1.19). BMD Z-scores were negatively associated with disease duration. Patients taking steroids were associated with lower Z-scores. In conclusion, SOS shows a significant correlation with BMD as measured by DXA, albeit with wide 95% confidence intervals in this small pilot study. QUS was also well tolerated and was technically easy to perform in these children. With the added advantage that it is free from radiation risk, further assessment of this potentially valuable tool for measuring bone status in children is warranted.