Juvenile idiopathic arthritis (JIA) is a chronic inflammatory disease of presumed autoimmune etiology that affects ~1 of 1,000 children worldwide . It is the most common chronic rheumatic disease in the pediatric age and an important cause of short-term and long-term disability. It is a heterogeneous condition, which is classified in 7 different categories based on the clinical manifestations observed in the first 6 months after onset [2, 3]. Some of these categories may represent different diseases, characterized by distinct modalities of presentation, clinical features, immune-pathogenesis and, in some cases, genetic background. The current International League of Associations of Rheumatology (ILAR) classification of JIA [2, 3] has the merit of having solved the drawback of the previous heterogeneity in nomenclature and criteria between Europe and North America. However, it has been subject to several criticisms. In particular, it has been argued that the clinical parameters used to separate patients in the various categories, namely the number of affected joints and the presence of psoriasis, may not lead to identify homogeneous disease subgroups .
The epidemiology of JIA is known to be variable worldwide. In particular, a wide disparity exists in the prevalence of the diverse disease subtypes between different countries. Although in the Western world the most common category is represented by oligoarthritis, this subtype is rare in countries such as Costa Rica, India, New Zealand, and South Africa, where polyarthritis predominates [5–8]. Similar discrepancies have been reported for juvenile spondyloarthropaties and for iridocyclitis, which is the main extra-articular complication of some JIA subsets, particularly those characterized by the presence of antinuclear antibodies (ANA). However, little data exists on the epidemiology of JIA. Furthermore, most studies have involved single countries and the comparison of the distribution of JIA categories across different geographic areas has seldom been attempted.
A number of therapeutic options are available for the management of JIA, ranging from NSAIDs to systemic or intra-articular corticosteroids, to the traditional disease modifying antirheumatic drugs (DMARDs), to the novel biologic agents [1, 9–11]. However, although treatment recommendations and standards of care for JIA have recently been published [12, 13], the therapeutic approach to JIA is not standardized and no treatment guidelines have been prospectively evaluated, internationally accepted, and widely and systematically implemented. As a result, the therapeutic choices for the management of individual patients are likely variable between pediatric rheumatologists practicing in single or different countries.
In the past decade, there have been several important advances in the management of JIA. In particular, the introduction of biologic agents holds great promise for the treatment of patients who are at greatest risk of developing irreversible structural damage to joints and permanent physical disability. A recent CARRAnet study found that 45% of JIA patients in the US are exposed to biologic DMARDs . However, the availability of biologic drugs is not uniform around the world. Due to their high cost, these medications or some of them may not be afforded by the national health care system of poorer countries or by the families of children living in these countries. As a result, many children with JIA around the world may not entirely benefit from the recent progresses in disease treatment. For some of these children, particularly those with the more severe systemic or polyarticular subtypes, the administration of high and prolonged doses of corticosteroids may be the sole therapeutic option to control disease activity symptoms. As a consequence, they are exposed to a high risk of experiencing serious and potentially devastating corticosteroid-related side effects. Altogether, these issues may have significant impact on disease prognosis and may place children living in poorer countries at greater risk of accumulating disease-related or treatment-related damage than children followed in Western pediatric rheumatology centers.
Owing to the aforementioned differences in epidemiology, treatment approaches, and availability of medications, there is likely an important variability in the outcome of children with JIA around the world. Although a number of long-term outcome surveys have been carried out in the last 4 decades [15–17], most of these studies have involved single centers or a few countries in the same geographic area (e.g., Scandinavia). The comparison of JIA disease outcomes between different parts of the world has never been attempted. Furthermore, most studies have evaluated patients with many years of disease duration, whereas the outcomes achieved with the present treatment, that is, the disease status of children currently followed in pediatric rheumatology centers, has seldom been investigated .
An important shortcoming of existing outcome studies lies in the use of a wide variety of clinical measures, which hampers comparability of results . Furthermore, most analyses have focused only on specific aspects of disease outcome, such as remission, functional disability, radiographic damage, or health-related quality of life (HRQL). In addition, children’s self-reported assessments have been seldom incorporated.
Most clinical measures currently used to assess the disease status, particularly functional ability and HRQL questionnaires, are lengthy and complex . For this reason, they are rarely applied in standard clinical practice to assess patient status and to monitor therapeutic response and disease course over time. However, it has been recommended that regular use of quantitative measures in daily practice may lead to improve the quality of patient care. To give an example, it has been suggested that the implementation of a treat-to-target strategy, based on treatment escalation if goal Juvenile Arthritis Disease Activity Score (JADAS) [20, 21] is not reached, in clinical practice may improve disease outcome . Furthermore, it is widely agreed that integration of parent- and child-reported outcomes in daily care may facilitate concordance with physician’s choices and compliance with therapeutic prescriptions [23–25]. To reach this goal, there is a need for outcome measures that are simple and easy to apply. In addition, to facilitate comparability of outcome data across different centers, such instruments need to be widely agreed upon and should be translated, cross-culturally adapted and validated in different languages according to established international guidelines .
Recently, a new multidimensional questionnaire that includes all main parent- and child-reported outcomes used in the clinical evaluation of children with JIA has been developed . This tool, named Juvenile Arthritis Multidimensional Assessment Report (JAMAR), may be well suited to collect parent- and child-reported information in standard clinical care.