Table 1

Outcomes and measurement

OutcomeMeasurePrePostFollow-up
PrimarySelf-efficacy to ask questionsSingle item adapted from Bandura’s self-efficacy theory.36 Participants are asked to rate their degree of confidence to ask questions of their healthcare provider by recording a number from 0 (cannot do at all) to 100 (highly certain can do).xxx
Self-efficacy to be involved in healthcare decision-makingSingle item adapted from Bandura’s self-efficacy theory.36 Participants are asked to rate their degree of confidence to be involved in decisions with their healthcare provider by recording a number from 0 (cannot do at all) to 100 (highly certain can do).xxx
Self-efficacy to ask questions and be involved in healthcare decision-makingComposite measure based on two individual items (see above).xxx
Intention to engage in shared decision-makingValidated, three-item scale (Cronbach alpha=0.8;31) measuring participants’ (a) likelihood of engaging in shared decision-making, from very unlikely (−3) to very likely (+3), (b) odds of engaging in shared decision-making, from very weak (−3) to very strong (+3) and (c) agreement with the statement ‘I intend to engage in shared decision-making', from total disagreement (−3) to total agreement (+3). Total scores will be rescaled on a scale of 0–6 and the sum of the items divided by three to derive the total score of intention.xxx
SecondaryIntention to follow the treatment plan recommended by the doctor without further questioningA single item on a 10-point scale, adapted from previous research,37 assessing hypothetical intention to follow the treatment plan recommended by the doctor without further questioning: ‘Which best describes your intention to follow the treatment plan recommended by the doctor without asking further questions?’ (1 = ‘Definitely will not’ to 10 = ‘Definitely will’).xxx
Knowledge of patients’ rights in regards to shared decision-makingFour questions adapted from Halaway et al 38 and applied to the Australian Charter of Healthcare Rights (second edition).39 Participants were asked to indicate ‘Yes’, ‘No’ or ‘Unsure’ to show whether they think the following are patient rights: (a) ask questions and be involved in open and honest communication; (b) make choices with your healthcare provider; (c) include the people that you want in planning and decision-making; (d) get clear information about your condition, including the possible benefits and risks of different tests and treatments. A foil question will be included to detect if participants are arbitrarily selecting ‘yes’ to all questions. Scores are dichotomised into (a) all questions correct, or (b) not all questions correct.xx
Attitude toward shared decision-makingThree-item scale adapted from Dormandy et al,40 assessing participants’ perceptions of shared decision-making as beneficial/not beneficial, worthwhile/not worthwhile and important/unimportant. Each item has seven response options, forming a scale from 3 to 21. Scores will be recoded such that higher scores indicate more positive attitudes towards shared decision-making. Participants responding with the highest possible score on all three questions will be classified as having positive attitudes.x
Preparedness for shared decision-making (Arms 1-3 only)Modified, eight-item version of the PrepDM.41 The PrepDM scale was developed to assess a participants’ perception of how useful a decision support intervention is in preparing them to communicate with their practitioner at a consultation visit and to make a health decision. Items are scored on a Likert scale 1–5, from ‘Not at all’ (1) to ‘A great deal’ (5), with higher scores indicating higher perceived level of preparation for decision-making. Items will be summed and the total score divided by 8.41 x
Acceptability (Arms 1–3 only)Adapted from Shepherd et al,42 participants are asked to rate if they would (a) recommend the (intervention) to others and (b) use the (intervention) again on a four-point scale from 1 (Definitely not) to 4 (Yes, definitely).42 Recommendations are dichotomised into would recommend (3 and 4) and would not recommend (1 and 2).x
Indicator of proactive intervention use (Arms 1–3 only)We will assess the proportion of participants who click on a link to their intervention.xx
Healthcare questionsParticipants will be asked to write down five questions that they would ask the doctor given the hypothetical healthcare scenario. The content of individual responses will be analysed via content analysis using inductive and deductive approaches (see below). The mean number of questions that map onto the Choosing Wisely 5 Questions will be calculated.xx
  • PrepDM, Preparation for Decision Making Scale.