Coping strategies and anxiety in association with methotrexate-induced nausea in juvenile idiopathic arthritis.

The aim of this study is to investigate whether methotrexate-induced nausea is associated with anxiety or the use of coping strategies in children with juvenile idiopathic arthritis (JIA) treated with methotrexate (MTX). This is an observational study of children diagnosed with JIA (ILAR criteria), treated with MTX and aged 9 years or above. MTX-induced nausea was determined by the children's completion of a nausea diary and the parents' completion of the Methotrexate Intolerance Severity Score (MISS). Anxiety was assessed by the Beck Youth Inventories-Anxiety Inventory (BYI-A) and coping strategies were evaluated by an adapted Nausea Coping Questionnaire. Enrolled were 121 children (82 girls: 39 boys) with a median age (IQR) of 13.3 (11.3-15.1) years. The median MTX-dose (IQR) was 9.7 (9.0-10.9) mg/m²/week. The median treatment duration (IQR) was 340 (142-766) days. The MISS was completed for 120 children; 77 children completed the nausea diary for at least 7 days. MTX-induced nausea was present in 61% (73/120) of the children according to the MISS and in 73% (56/77) of the children according to the nausea diary. MTX-induced nausea was associated with a more frequent use of the coping strategy internalizing/catastrophizing (MISS, p = 0.012; diary, p < 0.0001) and higher BYI-A raw scores (diary, p = 0.016). MTX-induced nausea was associated with anxiety and the use of coping strategies in children with JIA. These psychological factors may be part of the mechanism behind the inter-individual variation in the level of nausea to MTX treatment.