Chatbot-Assisted Advance Care Planning Education for Family Members

Recruitment rate will be assessed by calculating the percentage of eligible family members who provide study consent and actively participate in the study.

The proportion of participants who successfully complete all surveys and interview for outcome measures and intervention effect outcomes.

Fidelity refers to the extent to which core intervention components were delivered as planned by the research team.

Delivery indicators include:

Provision of assigned infographics Provision of assigned educational videos Respondent to inquiries Completion of scheduled nurse consultation sessions

Fidelity will be calculated as:

(Number of intervention components delivered as planned ÷ Total planned intervention components) × 100%.

Higher percentages indicate greater adherence to the intervention protocol.

Progression criterion: The intervention will be considered feasible if ≥90% of core intervention components are delivered in accordance with the protocol.

Participant engagement will be assessed using automatically recorded conversation logs from the messaging platform and chatbot system, as well as participant self-reported message reading extent.

Engagement indicators include:

• Number of interactions (instant messages, phone calls, or chatbot) recorded in the messaging platform and chatbot logs;
• Self-reported percentage of daily intervention messages read (0% = did not read any messages; 100% = read all assigned messages).

Interaction frequency will be reported as counts per participant. Message reading extent will be reported as a percentage (0-100%). Higher interaction frequency and higher reading percentages indicate greater engagement with the intervention.

Progression criterion: The intervention will be considered feasible if ≥50% of participants have at least one recorded interaction (via instant message, phone call, or chatbot) and report reading ≥50% of the daily intervention messages.

The scale evaluates message-delivered infographics across eight domains:

Trustworthiness Clarity Risk of confusion Difficulty to follow Usefulness Informativeness Comprehensibility Simplicity

Each item is rated using a 0-100% sliding scale (0 = lowest perceived usability; 100 = highest perceived usability).

For each domain, the mean score will be calculated. Higher scores indicate better perceived usability of the infographic content.

Progression criterion: The infographic content will be considered usable if the mean score for each domain is ≥78%.

Intervention acceptability will be assessed using an investigator-developed satisfaction survey. The survey evaluates three domains:

• Form of delivery
• Availability of customized support for advance care planning (ACP) questions
• Degree to which the intervention met participants' needs

Each item is rated on a 5-point Likert scale:

• = Highly dissatisfied
• = Dissatisfied
• = Neither satisfied nor dissatisfied
• = Satisfied
• = Highly satisfied

Scores range from 1 to 5 for each item. Higher scores indicate greater satisfaction and acceptability.

Progression criterion: The intervention will be considered acceptable if ≥70% of participants score 4 or 5 on all three items

Risk assessment will be conducted using self-reported adverse events.

The questionnaire includes demographics and care-related information.

Semi-structured qualitative interviews will be conducted at 3-month follow-up using an interview guide developed by the Principal Investigator. Interviews aim to explore family caregivers' experiences with the intervention, including perceived acceptability, logistics, and suggestions for improvement.

Interviews will be audio-recorded, transcribed verbatim, and analyzed using thematic analysis. Findings will be reported as identified themes and representative quotations.

Progression criteria: The intervention will be considered feasible if qualitative findings demonstrate overall positive perceptions regarding acceptability, logistics, and perceived usefulness of the intervention.

The Chinese version of the 10-item Family Members' Advance Care Planning (ACP) Readiness Questionnaire assesses family members' self-reported ACP knowledge, readiness to discuss ACP with a loved one, self-efficacy in initiating ACP conversations, perceived barriers, emotional perceptions and attitudes toward ACP, and perceived communication tools for ACP discussions.

Each item is rated on a 5-point Likert scale (1-5). Total scores range from 10 to 50, calculated by summing all items. Higher scores indicate greater ACP readiness.

The instrument was developed based on key domains reported in adult ACP readiness measures and constructs identified in a systematic review of family members' roles in ACP. The Chinese version has demonstrated good internal consistency (Cronbach's α = 0.86-0.90).

The Chinese version of the 17-item Advance Care Planning Engagement Survey for Surrogate Decision Makers assesses caregivers' engagement in the advance care planning (ACP) process.

The instrument comprises 17 items rated on a 5-point Likert scale (1-5). Total scores range from 17 to 85, calculated by summing all items. Higher scores indicate greater engagement in the ACP process.

The scale includes three domains:

Serving as a surrogate decision maker (7 items), Contemplation (4 items), and Readiness (6 items).

The instrument was adapted from the original 55-item ACP Engagement Survey and has been validated among surrogates of patients with chronic illness. The Chinese version has demonstrated high internal consistency (Cronbach's α = 0.90-0.91).

Participants will report a binary response ("Yes" or "No") to six advance care planning (ACP) behaviors widely used to evaluate ACP outcomes:

• Completion of a health care proxy;
• Communication with the resident regarding views about life-sustaining treatment;
• Communication with the resident regarding quality versus quantity of life;
• Communication between the resident and healthcare providers regarding life-sustaining treatment;
• Communication between the resident and healthcare providers regarding quality versus quantity of life;
• Completion of end-of-life documentation, including documentation of ACP in medical records, Advance Medical Directive (AMD), or Do-Not-Attempt-Cardiopulmonary-Resuscitation (DNACPR) forms.

For each activity, results will be reported as the number and proportion of participants selecting "Yes." A "Yes" response indicates that the specified ACP activity has been completed. A "No" response indicates that the activity has not been completed.