Efficacy of mobile CBT paired with active versus sham tDCS on pain intensity in adolescent survivors with chronic pain. The Brief Pain Inventory-Short Form (BPI) includes a 4-item pain severity scale. Participants rate their worst and least pain in the last 24 hours, average pain, and current pain using a 10-point rating scale (0=no pain to 10=pain as bad as you can imagine). The pain severity score was calculated as the average of the 4 items, with scores ranging between 0 and 10. Higher scores indicate greater pain intensity. Changes in pain intensity from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed both the baseline and 6-week assessment. All participants were included in the analysis.

Efficacy of mobile CBT paired with active versus sham tDCS on pain interference in adolescent survivors with chronic pain. Using the BPI, participants rate the impact of pain on general activity, mood, walking ability, normal work/school, relationships with other people, sleep and enjoyment of life using a 10-point rating scale (0=does not interfere to 10=completely interferes). The pain interference score was calculated as the average of the 7 items, with scores ranging between 0 and 10. Higher scores indicate greater pain interference. Changes in pain interference from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. All participants were included in the analysis.

The Pain Catastrophizing Scale, Child version (PCS-C) is a 13-item self-report measure of overly negative attitudes of pain. It consists of three scales of rumination, magnification and helplessness. The measure uses a 5-point rating scale (0=not at all true to 4=very true). The scores of three subscales were calculated as the sum of specific items: Rumination (4 items; score range 0-16), Magnification (3 items; score range 0-12), and Helplessness (6 items; score range 0-24). The total score was calculated as the sum of all 13 items (score range 0-52). Higher scores indicate worse outcomes (i.e., more pain rumination, magnification, helplessness and overall pain catastrophizing). Changes in pain catastrophizing from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. All participants were included in the analysis.

The Patient-Reported Outcomes Measurement Information (PROMIS) Pediatric Depressive Symptoms is an 8-item measure of self-reported symptoms of low mood in children and adolescents over the past 7 days. The measure has a 5-point rating scale (Never to Almost Always). The PROMIS Health Measures Scoring Service was used to convert raw scores to T-scores (population mean=50 and standard deviation=10. Higher scores indicate more severe depressive symptoms. Changes in depressive symptoms from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. All participants were included in the analysis.

The Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Anxiety is an 8-item measure of self-reported symptoms of anxiety symptoms in children and adolescents over the past 7 days. The measure has a 5-point rating scale (Never to Almost Always). The PROMIS Health Measures Scoring Service was used to convert raw scores to T-scores (population mean=50 and standard deviation=10). Higher scores indicate more severe anxiety symptoms. Changes in anxiety symptoms from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. All participants were included in the analysis.

The Fear of Cancer Recurrence Inventory is a 9-item measure developed specifically for survivors of childhood cancer (8-18 years) to assess the presence of fear of recurrence and perceived risk recurrence. The measure has 5-point rating scale (0=Not at All to 4=A Great Deal). The total score was calculated as the sum of all 9 items, with scores ranging between 0 and 36. Higher scores indicate greater cancer-related worry. Changes in cancer-related worry symptoms from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. One participant with incomplete data on the Fear of Cancer Recurrence Inventory was excluded from the analysis.

The Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Mobility is an 8-item measure of self-reported ability at physical activities in children and adolescents in the past 7 days. The PROMIS Pediatric Upper Extremity is an 8-item measure of self-upper extremity function in the past 7 days. Both measures have a 5-point rating scale (No Trouble to Not Able to Do). For both measures, the PROMIS Health Measures Scoring Service was used to convert raw scores to T-scores (population mean=50 and standard deviation=10). Higher scores indicate better outcomes (i.e., greater mobility and upper extremity function, respectively). Changes in physical functioning from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. All participants were included in the analysis.

The Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Peer Relationship is an 8-item measure that assesses the quality of peer relationships. The measure has a 5-point rating scale (Never to Almost Always). The PROMIS Health Measures Scoring Service was used to convert raw scores to T-scores (population mean=50 and standard deviation=10). Higher scores indicate better quality relationships with peers. Changes in peer relationship quality from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. All participants were included in the analysis.

The Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Fatigue is a 10-item measure that assesses symptoms of fatigue in the past 7 days. The measure has a 5-point rating scale (Never to Almost Always). The PROMIS Health Measures Scoring Service was used to convert raw scores to T-scores (population mean=50 and standard deviation=10). Higher scores indicate more fatigue. Changes in fatigue from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. All participants were included in the analysis.

The Adolescent Sleep Wake Scale (ASWS) short form is a 10-item measure of behavioral sleep patterns in adolescents. The measure has a 6-point rating scale (1=Never to 6=Always). The total score was calculated as the average of the 10 items, with scores ranging between 0 and 6. Higher scores indicating better success of sleep quality. Changes in sleep from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. One participant with incomplete data on the Adolescent Sleep Wake Scale (ASWS) short form was excluded from the analysis.

The Patient-Reported Outcomes Measurement Information System (PROMIS) Sleep-Related Impairment 8-item measure to allow for assessment of sleep quality during the night as well as the impact of sleepiness on daytime function. This measure assesses sleep-related impairment over the past 7 days. The measure has a 5-point rating scale (Never to Always). The PROMIS Health Measures Scoring Service was used to convert raw scores to T-scores (population mean=50 and standard deviation=10). Higher scores indicate more sleep problems. Changes in sleep from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. All participants were included in the analysis for the PROMIS Sleep-Related Impairment.

Acceptability and satisfaction with treatment will be assessed using a 5-point numerical rating scale (NRS) (strongly disagree to strongly agree). Higher score indicates greater acceptability and satisfaction. The answers were categorized as agree yes (strongly agree or agree) versus no (neither agree nor disagree, disagree, or strongly disagree).

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. All participants were included in the analysis.

At each timepoint participants and/or their parents will be asked to list the names of their medications, doses taken, and the frequency with which the medications were taken over the past 2 weeks. Opioid doses will be converted to morphine equivalent doses (MED; in mg) using an opioid equivalence table. Changes in opioid use from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Note: no participants reported taking opioids during the study

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. All participants were included in the analysis.

Parental depression will be measured at each time point using the Patient Health Questionnaire 8-item (PHQ-8), a measure of symptoms of major depressive disorder. The Patient Health Questionnaire is a 4-point rating scale (0=Not at All to 3=Nearly Every Day). The total score was calculated as the sum of all 8 items, with scores ranging between 0 and 24. Higher scores indicate greater depression. . Changes in parental depression from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. One participant with incomplete data on the Patient Health Questionnaire 8-item (PHQ-8) was excluded from the analysis.

Parental anxiety will be measured at each time point using the Generalized Anxiety Disorder 7-item (GAD-7), a measure of symptoms of generalized anxiety. The Generalized Anxiety Disorder measure is a 4-point rating scale (0=Not at 3=All to Nearly Every Day). The total score was calculated as the sum of all 7 items, with scores ranging between 0 and 21. Higher scores indicate greater anxiety. Changes in parental anxiety from baseline (enrollment) up to 8 weeks from the start of the intervention in the active treatment and placebo groups were reported.

Include participants in the feasibility study who were assigned to an experimental arm and completed the 6-week assessment. Two participants with incomplete data on the Generalized Anxiety Disorder 7-item (GAD-7) were excluded from the analysis.