Table 1.

Domains of DSP-Reported Engagement in Treatment Decisions

Domain	Definition	Items
Informed	Knowledge of risks & benefits of treatment options	When her treatment decisions were being made, did you get enough information about (y/n): • Risks/benefits of surgical treatment options • Coping with your loved one’s/friend’s cancer & treatment • Helping your loved one/friend manage side effects • Long-term effects of treatment • Risk of breast cancer recurrence
Involved	Extent of involvement in decision making	During the treatment making process how often did you (5-pt scale: Never -Very Often): • Attend doctor appointments where decisions about her treatment were discussed • Take notes for her during a doctor’s appointment • Talk to her about treatment options • Share information with her from other sources about treatment options (e.g., from the internet) • Help her manage side effects • Help take her to follow up appointments
	Satisfaction with involvement in decision making	Would you say you (5-pt scale: Not at all - Very Much): • Would like to have had more information when making treatment decisions • Would like to have participated more in making treatment decisions • Are satisfied with the amount of involvement you had when your loved one/friend was making treatment decisions • Are satisfied that you were adequately informed about the issues important to the decision about treatment
Aware	Of patients’ preferences and values	How much did your loved one/friend talk to you about how she felt about the pros and cons of (4-pt scale: Not at All -A Lot): • Different surgical options • Having radiation • Keeping or losing her breast(s) • Having chemotherapy