Appendix Electronic Supplemental Materials (ESM)

Proxies in End-of-Life Decisions, SUPPLEMENTAL MATERIALS 1

Appendix – Electronic Supplemental Materials (ESM)

Hypothetical Scenarios Questionnaire.Couples received one of three versions of the hypothetical scenario questionnaire in order to test hypotheses about the impact of positive versus negative framing,high versus low amounts of information, and the use of images on preferences for end of life medical treatments. The versions differed in the following four ways. 1) Form 1 and Form 3 framed the chance of success from CPRpositively, in terms of chance of survival for all CPR items (i.e., “90% chance of surviving after receiving treatment”), whereas Form 2 framed the chance of success from CPR negatively, in terms of chance of dying(i.e., “10% chance of dying after receiving treatment”) for all CPR items. 2) Form 1 and Form 3 included high levels of information for all mechanical ventilation items (e.g., “tube inserted down your throat”) and mentioned the treatment name (“mechanical ventilation”) multiple times, whereas Form 2 included little information on the procedure and mentioned the name once for the mechanical ventilation items. 3) Form 1 and Form 3 included information on length of hospital stay for all intravenous antibiotics items, whereas Form 2 did not include this information within intravenous antibiotics items. 4) Form 1 and Form 2 did not contain any photos or images of treatment options, whereas Form 3 contained photos or images of each of the four treatment items (CPR, mechanical ventilation, artificial nutrition, and intravenous antibiotics) next to the item. Thus Form 1 and Form 3 differed only on the presence of images.

In order to test for potential effects from positive or negative framing,high or low levels of information, and presence or absence of images, independent samples t-tests were run comparing the means for all treatment options across the three forms (see ESM Table 1). Only one significant difference was found between forms on the treatment preferences, on the artificial nutrition items, where couples who completed Form 3 (with an image) indicated greater interest in receiving this intervention than couples who completed Form 1 (without the image of artificial nutrition). Given the general lack of significant differences between forms, all couples/forms were combined in further analyses. Below is Form 3 which includes images.

Proxies in End-of-Life Decisions, SUPPLEMENTAL MATERIALS 1

Hypothetical Scenario Questionnaire - Form 3

The following questions ask about your treatment preferences in different medical situations. Please read through each scenario and the treatment options for that scenario. Then, indicate your preference for the treatment on the 5-point scale.

1. You are in your current health (the way you are feeling now):

a. If your breathing or heartbeat stops, medical personnel would administer cardiopulmonary resuscitation, or CPR, which is the use of drugs and electric shock to start the heart beating and artificial breathing. Imagine that you have approximately a 90% chance of surviving after receiving CPR and leaving the hospital. Please indicate whether or not you would want this treatment by circling your response from 1 to 5:

CPR

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