Contradictory and weak evidence on the effectiveness of anti-emetics for MTX-intolerance in JIA-patients

Methotrexate Intolerance in Juvenile Idiopathic Arthritis: Definition, Risks, and Management

Juvenile idiopathic arthritis is the most common rheumatic disorder in childhood and adolescence posing a significant threat of short-term and long-term disability if left untreated. Methotrexate is a folic acid analog with various immunomodulatory properties. It has demonstrated significant efficacy for the treatment of juvenile idiopathic arthritis, often considered the preferred first-line disease-modifying anti-rheumatic drug given as monotherapy or in combination with biological drugs. Despite this, there is a considerable risk for treatment disruptions owing to the high prevalence of methotrexate intolerance, with symptoms such as nausea, stomach ache, vomiting, and behavioral symptoms. Many different risk factors for the intolerance have been proposed including gender, age, disease activity, treatment duration, dosing and administration, and genetic and psychological factors. As the studies have shown contradictory results, many questions are left unanswered. Therefore, a consensus regarding outcome measures and reporting is crucial. In this review, we describe the identification and assessment of methotrexate intolerance and evaluate potential risk factors, genetic associations as well as management strategies.

MTX intolerance in children and adolescents with juvenile idiopathic arthritis

MTX is the medication most commonly used for antirheumatic treatment in juvenile idiopathic arthritis. It has high efficacy, is usually well tolerated and has an excellent safety profile. However, frequently intolerance symptoms develop that manifest as nausea, feelings of disgust or abdominal complaints prior to or directly after administration of the medication. No obvious toxicity is causing these intolerance symptoms, but symptoms are strictly limited to MTX and not transferred to other medications. MTX intolerance causes a significant reduction of quality of life in affected patients, frequently puts the treating physician in difficult situations regarding treatment choice, and may lead to uncomfortable decisions whether or not to stop an otherwise effective drug. Conventional countermeasures such as antiemetics, change of route from subcutaneous to oral or vice versa, or taste masking usually have only a limited effect. In this review, we present the current knowledge on MTX intolerance, its clinical picture and commonly employed strategies. We also consider newer behavioural treatment strategies that may offer a more effective symptom control.

Pharmacological conditioning for juvenile idiopathic arthritis: a potential solution to reduce methotrexate intolerance

BACKGROUND

Methotrexate (MTX) therapy has proven to be a successful and safe treatment for Juvenile Idiopathic Arthritis (JIA). Despite the high efficacy rates of MTX, treatment outcomes are often complicated by burdensome gastro-intestinal side effects. Intolerance rates for MTX in children are high (approximately 50%) and thus far no conclusive effective treatment strategies to control for side effects have been found. To address this need, this article proposes an innovative research approach based on pharmacological conditioning, to reduce MTX intolerance.

PRESENTATION OF THE HYPOTHESIS

A collaboration between medical psychologists, pediatric rheumatologists, pharmacologists and patient groups was set up to develop an innovative research design that may be implemented to study potential improved control of side effects in JIA, by making use of the psychobiological principles of pharmacological conditioning. In pharmacological conditioning designs, learned positive associations from drug therapies (conditioning effects) are integrated in regular treatment regimens to maximize treatment outcomes. Medication regimens with immunosuppressant drugs that made use of pharmacological conditioning principles have been shown to lead to optimized therapeutic effects with reduced drug dosing, which might ultimately cause a reduction in side effects.

TESTING THE HYPOTHESIS

This research design is tailored to serve the needs of the JIA patient group. We developed a research design in collaboration with an interdisciplinary research group consisting of patient representatives, pediatric rheumatologists, pharmacologists, and medical psychologists.

IMPLICATIONS OF THE HYPOTHESIS

Based on previous experimental and clinical findings of pharmacological conditioning with immune responses, we propose that the JIA patient group is particularly suited to benefit from a pharmacological conditioning design. Moreover, findings from this study may potentially also be promising for other patient groups that endure long-lasting drug therapies.

[Methotrexate in juvenile idiopathic arthritis. Adverse effects and associated factors]

INTRODUCTION

Methotrexate (MTX) is the drug of choice for juvenile idiopathic arthritis. Its clinical efficacy is limited due to the development of adverse effects (AEs).

PATIENTS AND METHODS

A retrospective observational study was conducted on the AEs associated with MTX therapy in children diagnosed with juvenile idiopathic arthritis followed-up in a tertiary hospital between 2008 and 2016.

RESULTS

The study included a total of 107 patients, of whom 71 (66.3%) were girls (66.3%). The median age at diagnosis was 6.4 years (IQR 3.1-12.4), with a median follow-up of 45.7 months (IQR 28.8-92.4). There were 48 patients (44.9%) with oligoarthritis, and 26 children (24.3%) with rheumatoid-factor negative polyarthritis. Of these, 52/107 (48.6%) developed AEs, with the most frequent being gastrointestinal symptoms (35.6%) and behavioural problems (35.6%). An age older than 6 years at the beginning of therapy increased the risk of developing AEs, both in the univariate (OR=3.5; 95% CI: 1.5-7.3) and multivariate (12% increase per year) analyses. The doses used, administration route, or International League of Associations for Rheumatology (ILAR) classification, were not associated with the development of AEs. Twenty children required a dosage or route of administration modification, which resolved the AE in 11 (55%) cases. MTX was interrupted due to the development of AEs in 37/107 patients (34.6%), mainly due to increased plasma transaminases (n=14, 37.8%), gastrointestinal symptoms (n=9, 24.3%) and behavioural problems (n=6, 16.3%).

CONCLUSIONS

MTX is the therapy of choice for patients with juvenile idiopathic arthritis, but 50% of the children develop some form of AE. Although the AEs are not severe, they lead to interruption of therapy in 35% of the children.