Table 2.

Summary of the studies included in the systematic review

DA ID	First author, year	Country	Study design	Study population	Methods	Results
1,2	Harwood, 2011	AUS	Development/Evaluation and pilot study	Development/Evaluation study: women who had already had surgery for breast cancer (stages I and II, n  = 28) Pilot study: newly diagnosed patients with early breast cancer (stages not mentioned, n  = 11)	There were two phases of this study. The first phase involved patients evaluating the two DAs, and the second phase involved determining the effectiveness of the DAs. During both phases, study outcomes were treatment chosen, patient knowledge, decisional conflict, and satisfaction with decision-making.	Patients in the historical control group reported positive feedback on the DAs, and patients in the intervention pilot group found the DAs to be helpful. Results from the pilot study suggested a possible reduction in decisional conflict, and increase in decisional satisfaction, knowledge, and choice of axillary clearance (instead of sentinel node biopsy) in the intervention pilot group.
6	Zdenkowski, 2016	AUS	Development/protocol evaluation study	Newly diagnosed patients with invasive and operable breast cancer (target n  = 50)	A pre-post design will be used to evaluate the acceptability and feasibility of the DA. Primary outcomes will be acceptability and feasibility, and secondary outcomes will be decision conflict, knowledge, information and involvement preference, agreement between preferred and achieved decision.	N.A.
6	Zdenkowski, 2018	AUS	Evaluation study (pre-post design)	Newly diagnosed patients with operable invasive breast cancer (n  = 59)	Patients first completed a baseline questionnaire (test 1), subsequently received the DA prior to consultation, and then completed a follow-up questionnaire after consultation (test 2), before surgery (test 3) and 12 months after registration (test 4). Study outcomes: as above.	The DA was found to be feasible (with most patients having accessing it) and acceptable (with the majority of the patients seeing the DAs as useful for their decision about treatment). Moreover, post-DA, decisional conflict, anxiety, and distress decreased significantly.
7	Jibaja-Weiss, 2006	USA	Evaluation study	Newly diagnosed patients with early breast cancer (stages I–IIIA, n  = 51)	Patients answered a number of questions after diagnosis, and after completing the DA. Study outcomes were patients’ use of the values clarification exercise, perceived clarity of values, and decision conflict scores (low literacy version).	Over half of the participants performed the values clarification exercise. The use of the DA was associated with lower levels of decisional conflict (compared to baseline scores) and lower levels of feeling unclear about values.
7	Jibaja-Weiss, 2011	USA	RCT	Newly diagnosed patients with early breast cancer (stages I–IIIA, n  = 76)	Patients were randomized to either the intervention group (DA plus usual care) or the control group (usual care only). Study outcomes were treatment preference, breast cancer knowledge, satisfaction with decision, satisfaction with decision-making process, and decision conflict (low literacy version).	Patients who received the DA were more likely to indicate a preference for mastectomy rather than breast-conserving surgery, were more knowledgeable and clearer about their values compared to the control group. No differences were found in satisfaction with the decision or the decision-making process between the two groups.
9	Hawley, 2016	USA	Evaluation and pilot study	Newly diagnosed patients with early breast cancer (stage 0, I, or II, n  = 101)	Patients were randomized to either the intervention group (who viewed the DA first) or the control group (who took a survey prior to viewing the DA). Study outcomes for the evaluation were knowledge (about treatment options and breast cancer) and decisional appraisal.	Patients who viewed the DA first had higher scores on decisional appraisal than the control group. However, no statistically significant differences were found in knowledge about treatment options between the two groups.
9	Hawley, 2017	USA	RCT protocol	Newly diagnosed patients with early breast cancer (DCIS, or stage I–II, target n  = 222 per arm)	A two-arm RCT will be conducted to evaluate the impact of a tailored DA (intervention group) on decision quality, decision satisfaction, deliberation, and decision preparedness (as primary study outcomes) compared to the same non-tailored static DA (control group).	N.A.
9	Hawley, 2018	USA	RCT	Newly diagnosed patients with early breast cancer (stage I–II, n  = 496)	Patients were randomly allocated to the intervention group (tailored DA) or control group (non-tailored static DA). Primary study outcome was high-quality decision-making (which consisted of (1) knowledge about risks and benefits of treatment options and (2) values-concordant treatment).	The use of a tailored DA was positively associated with high-quality decisions compared to using a non-tailored DA. Furthermore, patients in the intervention group had higher levels of knowledge than the control group. However, no differences were found in values-concordant treatment decisions between the two groups.
13	Sherman, 2016	AUS	RCT	Newly diagnosed patients with early breast cancer or ductal carcinoma in situ (DCIS, stages I–III, n  = 222)	An RCT was conducted to determine the effectiveness of a DA for deciding whether to have breast reconstruction or not. Patients were randomized to either the intervention group (DA + plus standard information) or the control group (standard information). Study outcomes were decisional conflict, satisfaction with information, and decisional regret (1 and 6 months after exposure).	At both 1- and 6-month follow-up, the use of the DA was associated with lower levels of decisional conflict and higher levels of satisfaction with the information compared to the control group. There were no differences in decisional regret between the two groups.
14	Wong, 2011	CAN	Development and evaluation study	Development study: patients with early breast cancer who had already had radiotherapy (stage I, n  = 12) Evaluation study: Newly diagnosed patients with early breast cancer (stage I, n  = 36)	There were two pilot studies in this study. The first involved the development of the DA in which patients were asked to review the acceptability of the aid. The second pilot was a pre-post test aimed at examining the effectiveness of the DA on decisional conflict, knowledge, impact of event, and treatment choice.	The majority of patients rated the DA as (extremely) satisfied. In comparison to the baseline scores (pre-test), patients experienced less decisional conflict and were more knowledgeable after using the DA (post-test).

DA decision aid, N.A. not applicable, RCT randomized controlled trial