SDOTS: Self-Determination Theory-informed Occupational Therapy Program to Increase Physical Activity Among Survivors of Breast Cancer

Recruitment rates will be reported as the proportion of BC survivors enrolled in the study divided by the number of BC survivors who complete the screening survey. Enrollment will be considered feasible if ≥70% of eligible and approached BC survivors consent and enroll.

Study retention will be the number of BC survivors completing the program divided by the number that started. Retention will be considered feasible if ≥80% BC survivors who complete the baseline measures also complete measures post-program.

The number of weekly telehealth-delivered OT sessions (out of eight total sessions) that each participant attends will be used as the program adherence metric. Adherence will be considered feasible if participants average ≥80% attendance OT sessions.

Assessments of program safety will be assessed by tracking any BC-related lymphedema events, musculoskeletal injuries, and adverse events. The occupational therapist will track this information each week during each participant's telehealth-delivered OT session. The program will be considered safe if these events occur at or below published normative values.

We will assess participants' pre- to post-program changes in SDT constructs through examinations of basic psychological needs satisfaction in exercise. We will operationalize these constructs using the Basic Psychological Needs in Exercise Scale. This 11-item Likert-type scale that features three subscales that measure perceptions of autonomy, competence, and relatedness (1: "I don't agree at all"; 5: "I completely agree").

This measure will allow us to assess participants' perceptions of having experienced the SDT's underlying mechanisms of behavior change (autonomy, competence, and relatedness) as well as meaning associated with the intervention's aim (i.e., to increase engagement in personally meaningful physical activities). Responses are on a 7-point Likert-type scale (1: "Strongly disagree"; 7: "Strongly agree"), with higher scores better.

The Supportive Accountability Inventory will allow us to assess the degree of supportive accountability participants felt the study occupational therapist provided during the course of the program. Participants will respond on a 7-point Likert scale (1 = 'Strongly disagree; 7 = 'Strongly agree').

Measurements of pre- to post-program changes in aerobic PA will be completed using ActiGraph GT3X accelerometers. Durations of moderate-vigorous physical activity [MVPA], light physical activity [LPA], and sedentary behavior (SB) reported will aggregated and reported as our single overall physical activity metric.

Pre- to post-program changes in weekly MSE bouts will be tracked as the occupational therapist discusses PA goals with each participant during their once-weekly OT session. The occupational therapist's notes will be used to determine the percentage of program weeks that BC survivors meet the recommended two bouts of MSE per week.

We will evaluate pre- to post-program changes in HRQoL using patient-reported outcomes. We will assess the following eight components of physical and psychological health at baseline and post-program using the Patient-Reported Outcomes Measurement Information System (PROMIS): physical functioning, fatigue, anxiety, depression, pain interference, pain intensity, sleep impairment, and sleep disturbance. Measurements on the PROMIS are on a 5-point Likert-type scale, with 5 reflecting worse outcomes on all components aside from physical function wherein a higher score reflects better physical function. These PROMIS measures have been observed as reliable tools for the assessment of these outcomes.

We will measure Goal attainment via goal attainment scaling (GAS). Measurement/Analysis: GAS allows for reporting the extent to which a participant meets weekly goals using a 5-point scale (-2 [minimum]: performance was much worse than expected; +2 [maximum]: performance was much better than expected). Measurement of pre-post changes obtained through transforming into a single aggregate score using established protocols.

We will collect social and demographic variables at baseline to ensure we can best describe our sample and explain observation nuances (e.g., age, sex, race/ethnicity, education, height and weight, marital status, annual household income, date of BC diagnosis and stage at diagnosis, type of BC treatment(s) received, comorbidities [e.g., type II diabetes], readiness to change, and overall health status).