Kindness Interventions in Enhancing Well-Being in Breast Cancer Survivors

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Big-5 Personality Dimensions measured by the Ten-Item Personality Inventory (TIPI) measured at baseline: Personality dimensions will be measured at baseline by the 10-item TIPI. There are 5 subscales on the TIPI, each with 2-items: Extraversion, Agreeableness, Conscientiousness, Emotional Stability, and Openness to Experience. Scores on each subscale range from 2 to 14, with higher scores indicating greater endorsement of the corresponding personality domain.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Empathy measured by the Perspective Taking \& Empathic Concern Subscales of the Interpersonal Reactivity Index: Empathy will be measured pre- and post-intervention using the 6-item Perspective Taking (range: 0 to 30) and 7-item Empathic Concern Subscales (range: 0-35) of the IRI. Higher scores indicate greater characteristics of empathy.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Fatigue measured by the Severity items of the Fatigue Symptom Inventory (FSI): Fatigue will be measured pre- and post-intervention using the 4-item Severity subscale of the FSI. Scores range from 0 to 40, with higher scores indicating greater severity.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Fulfillment of psychological needs measured by the Balanced Measure of Psychological Needs: Fulfillment of psychological needs will be measured weekly using the 9-item Balanced Measure of Psychological Needs. Scores range from 5 to 45, with higher scores indicating greater life satisfaction.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Life Satisfaction measured by the Satisfaction with Life Scale: Satisfaction with life will be measured pre- and post-intervention using the 5-item Satisfaction With Life Scale. Scores range from 5 to 35, with higher scores indicating greater satisfaction. A score of 31 to 35 represents "extremely satisfied," for example.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Pain measured by the Pain Subscale of the Rand Health 36-item Short Form Survey (SF-36): Pain severity and interference will be measured pre- and post-intervention using the 2-item pain subscale of the SF-36. Scores range from 0 to 100, with higher scores indicating less severity/interference.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Positive and negative affect measured by the Affect-Adjective Scale: Positive and negative affect will be measured weekly using the 9-item Affect-Adjective Scale. Three additional adjectives (i.e., embarrassed, uncomfortable, ashamed) were added by the researchers. Scores on the 4-item positive affect subscale range from 0 to 24, with higher scores indicating more positive affect. Scores on the 5-item negative affect subscale range from 0 to 30, with higher scores indicating greater negative affect.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Qualitative assessment of acts performed: At the end of each week, participants will be asked to report on their weekly activities via a free response text box. The content of these activities may be coded or analyzed to provide context to quantitative data.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Self-kindness measured by the Self-Compassion Scale (SCS): Dispositional self-kindness will be measured pre- and post-intervention using the 5-item Self-Kindness Subscale of the SCS. Total scores on the Self-Kindness Subscale range from 5 to 25, with higher scores indicating greater levels of self-compassion.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Sleep disturbance measured by the PROMIS Sleep Disturbance Scale: Sleep disturbance will be measured pre- and post-intervention using the 4-item PROMIS Sleep Disturbance Scale. Scores range from 4 to 20, with higher scores indicating more disturbance.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Social connection measured by the Attachment Subscale of the Social Provisions Scale: Social connection will be measured pre- and post-intervention using the 4-item Attachment subscale of the Social Provisions Scale. Scores range from 4 to 16, with higher scores indicating greater social connection.

Analyses will be conducted under the intent-to-treat principle, including all participants in their assigned condition, accomplished by fitting models to all available data for each outcome measure, including data of participants with incomplete follow-up. Linear mixed models provide valid inferences under a missing at random assumption. Differences between conditions in change over time will be examined by testing condition-by-time interaction terms. Analyses will control for any participant characteristics with baseline imbalance among conditions or that differ between participants retained.

Social support measured by the 2-way Social Support Scale: Social support will be measured pre- and post-intervention using the 21-item 2-way Social Support Scale. Total scores range from 0 to 105, with higher scores indicating more perceived support.