Background/Purpose: Methotrexate (MTX) is the mainstay treatment in the therapy of children with juvenile idiopathic arthritis (JIA) and can lead to prolonged remission and improved quality of life. However, JIA patients frequently develop intolerance to MTX, with anticipatory and associative gastrointestinal adverse effects before drug intake arising as a conditioned response. Parents frequently try to alleviate these symptoms with a variety of countermeasures reported to help against nausea.

 The objective of this study was to investigate the course of MTX intolerance in pediatric patients over a period of 6 months, as well as the effect of countermeasures by parents on the severity of MTX intolerance.

Methods: Consecutive patients admitted to the German Center for Pediatric and Adolescent Rheumatology from October 2012 until April 2014 were included in this study. MTX intolerance was measured using the validated Methotrexate Intolerance Severity Score (MISS) questionnaire. Inclusion criteria were 1) diagnosis of JIA, 2) treatment with MTX for at least 3 months prior to inclusion, and 3) confirmation of MTX intolerance by a MISS value of ≥ 6. Exclusion criteria were other diseases leading to nausea and/or abdominal complaints, and concomitant medications possibly inducing nausea (excepting biologics and non-steroidal anti-inflammatory drugs). Methotrexate dose, MISS and countermeasures instituted by the parents were determined at 4 time points (at inclusion, at 6 weeks, 3 months and 6 months). Countermeasures were classified into 4 criteria: antiemetic drugs, covert dosing, taste masking and complementary medicine. Results were analyzed using descriptive statistics and non-parametric testing (Wilcoxon signed rank test).

Results:38 patients were included (63% female, median age at inclusion 11.7 years, median disease duration  7.1 years).  Average MISS at inclusion was 10.8 ± 4.1, and after 6 months 12.2 ± 7.2 (p = 0.316).  In 6/38 patients (16%), MTX was reduced or discontinued during the study. In 89 time intervals between study visits, 40 countermeasures were introduced by the parents.

Countermeasure	n	MISS before introduction	MISS after introduction	p
Antiemetic drugs	9	10.56	13.78	.080
Covert dosing	11	12.64	12.64	.766
Taste masking	9	11.67	13.22	.120
Complementary medicine	11	12.73	14.18	.089

Conclusion: If MTX intolerance is present, symptoms will not decrease over the course of 6 months. Various modalities used by the parents as countermeasures against nausea show no discernible effect.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/countermeasures-against-methotrexate-intolerance-in-juvenile-idiopathic-arthritis-instituted-by-parents-show-no-effect/