The EUC arm is designed to account for potential effects on time and standard medical care outcomes. Patients randomized to EUC will continue with standard care and optimal management of their SCD and chronic pain for approximately 8 months (i.e., time from enrollment through 6-month post-treatment assessment) before starting the intervention program to coincide with the study duration of the ES arm. After completing the 6-month follow-up assessment, patients will have the opportunity to start the I-STRONG for SCD intervention.

Depressive symptoms in past two weeks among teen study participants and parents is assessed with the Patient Health Questionnaire (PHQ-8). The PHQ-8 has 8 items that are responded to on a 4-point scale where " not at all" = 0 and "nearly every day" = 3. Total scores range from 0 to 24 where higher scores indicate increased symptoms of depression.

The outcome applies to teens and parents.

General worry in the past two weeks among teen study participants and parents will be assessed using the GAD-2 instrument. The GAD-2 has 2 items that are responded to on a 4-point scale where " not at all" = 0 and "nearly every day" = 3. Total scores range from 0 to 6 where higher scores indicate increased experiences of worry.

The outcome applies to teens and parents.

Exaggerated worried thoughts of pain will be assessed among teen study participants and parents. The Pain Catastrophizing Scale, Child and Parent Report, is a 13-item well-validated self-report and parent-report measure of worried thoughts about pain. Items are answered on a 5-point scale where 0 = not true at all and 4 = very true. Total scores range from 0 to 52 and higher scores indicate increased catastrophic thinking.

The outcome applies to teens and parents.

Health-related quality of life and impact on child and family in the past month is assessed among teen study participants and parents with the Pediatric Quality of Life Inventory (PedsQL). The 23-item PedsQL was developed as part of the NIH Roadmap Initiative to create universal measures for patient-reported outcomes and contains questions in the domains of social peer, depression, anxiety, mobility, and function. Responses are given on a 5-point scale where 0 = never and 4 = almost always. Items are reverse scored and linearly transformed to a scale of 0 to 100, where higher total mean scores indicate a better quality of life.

The outcome applies to teens only.

The Adolescent Sleep Wake Scale (ASWS) Short Form is a 14-item patient report describing the occurrence and frequency of various behavioral sleep characteristics over the past month. Responses are given on a 6-point Likert scale where 1 = always and 6 = never. Total scores range from 14 to 84 and higher scores indicate better sleep quality.

This outcome applies to teens only.

Substance use among teen study participants during the past 3 months is assessed with the NIDA-Modified Assist Tool Level 2 for children aged 11-17. The instrument asks respondents how often they have used 15 different substances. Responses are given on a 4-point scale where "not at all" = 0 and "nearly every day" = 4. The tool is scored as the number of items with a score greater than 0 and multiple items with scores above 0 indicate increased substance use.

This outcome applies to teens only.

Daily use of opioid pain medication will be determined based on participant completion of daily diaries for 1-week at each assessment visit. Participants will record opioid use daily (yes/no).

An electronic medical chart review will determine opioid morphine milligram equivalent (MME) calculation in the past month, with higher scores indicating higher MME per day.

The overall self-reported rating of the treatment's efficacy will be assessed with the Patient's Global Impression of Change (PGIC) instrument. The PGIC asks respondents to rate their overall improvement compared to the baseline. Responses are indicated on a scale of 1 to 7, where 1 = very much improved and 7 = very much worse.

This outcome applies to teens only.

Teens and parents will complete the Treatment Evaluation Inventory-Short Form at the end of treatment. This form includes 9 items adapted to be specific to pediatric pain. Items are rated on a 5-point Likert scale ranging from 1 to 5. Total scores range from 9 to 45. Higher scores indicate increased acceptability with the study treatment.

This outcome applies to teens and parents

Fear of movement related to fear of pain is assessed with the Tampa Scale of Kinesiophobia (TSK) instrument. The TSK is a 17-item questionnaire where responses are given on a 4-point Likert scale. Responses of "strongly agree" are coded as 1 and responses of "strongly agree" are coded as 4. Total scores range from 17 to 68 where higher scores indicate greater kinesiophobia.

This outcome applies to teens only.

Perceptions of a child's tiredness and energy will be measured using the Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Fatigue Short Form. It consists of 10 items scored on a Likert-type scale ranging from 1 (never) to 5 (almost always). The total possible range is 10-50, with higher scores representing greater fatigue or lower energy, while lower scores indicate better energy levels or less fatigue.

The outcome applies to teens and parent-proxy.

The 20-item CPAQ-revised has been designed to measure acceptance of pain. The acceptance of chronic pain is thought to reduce unsuccessful attempts to avoid or control pain and thus focus on engaging in valued activities and pursuing meaningful goals. The items on the CPAQ are rated on a 7-point scale from 0 (never true) to 6 (always true). To score the CPAQ, the Activity engagement and Pain willingness items are added to obtain a score for each factor. All the scores for each factor are summed to get the total score. Higher scores indicate higher levels of acceptance.

The outcome applies to teens only.

The Child Self-Efficacy Scale (CSES) is a self-report tool that examines self-efficacy despite pain to assess normal functioning and behavior. The CSES is a 7-item form asking how sure a child can perform certain activities while in pain. An 11-point scale with anchor points being 0 (cannot do at all), 5 (moderately certain can do), and 10 (certain can do). A higher score suggests that a person is more confident in their ability to cope and function with pain.

The outcome applies to teens and parent-proxy.

TFI-8 is a brief, reliable, and valid measure used for continuous process measurement and feedback to improve the functioning of therapy groups. The TFI-8 is given to participants after group therapy sessions to assess group cohesion. It typically consists of 8 items that respondents rate based on their experiences. Participants usually respond using a Likert scale (e.g., 1 to 5), where 1 may indicate "strongly disagree" and 5 indicates "strongly agree." The total score is calculated by summing the responses for all items. Higher total scores generally indicate a greater presence of therapeutic factors perceived by the participants.

The outcome applies to teens only.