Despite the widespread use of subcutaneous methotrexate in treating pediatric rheumatic disorders, the amount of pain associated with the injections has not been quantified. Our study aims 1) to quantify the amount of pain associated with subcutaneous injections of methotrexate, 2) to explore predictors of pain, 3) to determine the frequency of patient-reported clinical adverse effects of methotrexate, and 4) identify coping strategies of patients and caregivers.
Patients aged 4-17 years with rheumatologic diseases who were receiving weekly subcutaneous methotrexate injections for at least 4 weeks were invited to participate in this prospective cohort study. They were trained to use the Faces Pain Scale-Revised (FPS-R) and Faces, Legs, Arms, Cry, Consolability (FLACC) tools to rate pain associated with the injections. All patients underwent focused interviews exploring their experiences with methotrexate injections.
Forty-one patients consented to the study. The mean age was 11.2 years (SD = 3.9 years) and 68% were female. Most patients were diagnosed with JIA (73%). Mean duration of methotrexate therapy was 2.5 years (SD = 2.1 yrs). All but one of the patients used methotrexate 25 mg/ml solution for injection in 1 cc or 3 cc syringe with 30 gauge ½" needle. Median amount of pain was 2/10 on the FPS-R and 1/10 on the FLACC. Higher intensity of pain was significantly associated with presence of side effects (p = 0.004), but not duration of therapy (p = 0.20) or age (p = 0.24). Most participants (61%) experienced at least one adverse effect; nausea (56%) and vomiting (34%) were the most common symptoms reported. Patients and caregivers reported using ice (34%), comfort positions (51%), rewards (49%), reassurance (54%), distraction (51%), and analgesic medications (22%) to cope with the injections.
Subcutaneous injections of methotrexate are associated with a mild amount of pain. Presence of side effects may amplify the amount of perceived pain. Clinicians can apply this knowledge when counseling patients and family members about methotrexate therapy.