Interactive Decision Aid for Men Diagnosed With Prostate Cancer

The Decisional Conflict Scale (DCS) is a measure that was designed to evaluate health-care-consumer decisions. It is a 16-item measure and the answers range from "strongly agree" to "strongly disagree" on a five point Likert scale. Scores on DCS range from 0 to 100, were higher score indicate greater decisional conflict. It has test-retest reliability of 0.81 and internal consistency ranges from α=.0.78 to 0.92.

The Decision Regret Scale (DRS) measures regret after health care decision. It is a 5-item measure and the answers range from "strongly agree" to "strongly disagree" on a five point Likert scale. Scores on DRS range from 0 to 100, were higher score indicate more regret after health care decision. It has good internal consistency that ranges from α=.0.81 to 0.92.

The Satisfaction with Decision Scale (SWDS) measures satisfaction with health care decision. It is a 5-item measure and the answers range from "strongly agree" to "strongly disagree" on a five point Likert scale. Scores on SWDS range from 5 to 25, were higher score indicate more satisfaction with a decision.The scale has good internal consistency (α=.0.86).

The Generalized Anxiety Disorder - 7 (GAD-7) is a 7-item measure used to screen for general anxiety disorder and to measure its severity. It is also a good screening tool for social anxiety disorder, panic disorder and post traumatic stress disorder. Response options range from "not at all" to "several days" on a 4-point Likert scale. GAD-7 total score ranges from 0 to 21, were higher score indicates more severe anxiety. It has excellent internal consistency (α = 0.92).

The Patient Health Questionnaire (PHQ-9) is a widely used and well validated measure used to screen for depression and assess severity of it. It is a 9-item scale and answers are on 4-point Likert scale ranging from "not at all" to "nearly every day". PHQ-9 total score ranges from 0 to 27, were higher score indicates more severe depression. PHQ-9 has been shown to be a reliable and valid measure.

The Perceived Stress Scale (PSS-10) is a 10-item scale used to measure stress. Each item on the list is rated on a five point Likert scale ranging from "never" to "very often". PSS-10 total score ranges from 0 to 40, were higher score indicates higher perceived stress. The PSS has adequate reliability and validity.

The NCCN Distress Thermometer and checklist is a widely used screening measure for distress in cancer patients. It consists of a distress thermometer where participants assess their distress on a scale from 0 to 10, were 0 indicates no distress and 10 extreme distress. Additionally participants answer a problem checklist with several domains to identify what area of life distresses the participant.

The Impact of events scale-revised (IES-R) is a widely used questionnaire that measures trauma related stress, that is cancer specific distress. It is a 22-item measure that includes three factors; avoidance, hyper arousal and intrusion. Those factors together form a cancer-specific distress measure and the higher the score on the scale suggest more distress. Total score range from 0 to 88. The IES-R has high internal consistency and test-retest reliability ranges from 0.51-0.94.

The control preference scale (CPS) assesses the patient's preferred role in the decision-making process. It measures how people with life-threatening illnesses make treatment decisions. It measures the degree of control a person wants to have when making a medical treatment management decision.The scale is a single item and displays five possible roles of patient in decision making, that is fully passive, semi-passive, collaborative, semi-active and fully active.

The localized prostate cancer knowledge scale is a 9-item list that assesses participants knowledge of localized prostate cancer and prostate cancer management options. The scale was developed for this study based on method used by Berger, Grønberg, Loge, Kaasa and Sand (2018). Total score range from 0 to 9, were higher score indicates better knowledge of localized prostate cancer and prostate cancer management options.

The Health Information Orientation Scale (HIOS) measures underlying reasons for avoiding or seeking information in health context. The scale consists of 8 items and has two factors, that is information engagement and information apprehension. Both factors show adequate construct validity and reliability. Total score range from 0 to 32, were higher score indicates greater information apprehension and information engagement.

The Intolerance of uncertainty-12 (IUS-12) measures response to ambiguous situation and uncertainty. The scale consists of 12 items. Total score range from 12 to 60, where higher score indicates greater intolerance of uncertainty. The IUS shows good psychometric properties.