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Table 2 Constructs and measures for evaluating the efficacy of the PREPARE Study

From: The advance care planning PREPARE study among older Veterans with serious and chronic illness: study protocol for a randomized controlled trial

Construct

Measure

# items

Reliability/validity

Screener

Baseline

1 week

3 month

6 month

 

Eligibility screening variables

       

Cognitive impairment

Short Portable Mental Status Questionnaire (SPMSQ)

7

Sensitivity 86.2 %, specificity 99.0 % [43]

X

    

0 to 2 = eligible

3 to 7 moderate impairment (go on to the Mini Cog three-item recall)

≥8 severe impairment = ineligible

Cognitive impairment (participants scoring 3 to 7 errors on the SPMSQ)

Mini Cog (three-item recall as needed, if SPMSQ screen + for cognitive impairment)

3

Sensitivity 76 %, specificity 89 % [44]

X

    

If recall ≥ two words = eligible

Vision

Ability to see words on a newspaper [42]

1

      
 

Moderator variables

       

Demographic information

Age, gender, race/ethnicity [45], income, marital status, and education

  

X

X

   

Health literacy screen

“How comfortable are you filling out medical forms by yourself?”

1

AUROC 0.80 (95 % CI = 0.67.0.93) for inadequate health literacy [46]

X

    

“Qué tan seguro (a) se siente al llenar formas usted solo (a)”

Health literacy assessment

Short form Test of Functional Health Literacy in Adults s-TOFHLA, scores 0 to 36) [47] Continuous & dichotomized to limited = 0 to 22 and adequate = 23 to 36

36

Cronbach’s α = .97

 

X

   

Correlation coefficient w/ other literacy tests > 0.80 [47]

United States acculturation

Based on Acculturation scale (USAS) “How many years have you lived in the U.S.?”

1

Cronbach’s α = .98

 

X

   

Associated w/ desire to know prognosis [48]

Finances

“In general, how do your finances usually work out at the end of the month?”

1

Associated with functional impairment and comorbidity [49]

 

X

   

Socioeconomic status and social standing

Social standing ladder (that is, place an “x” where you think you stand relative to other people in society)

1

Associated with functional decline [50]

 

X

   

Functional status

Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL)

15

Morbidity/mortality correlation [51, 52]

 

X

   

Self-rated health status

In general how would you rate your health? (5-pt Likert)

1

Correlation with global health, spearman’s rho = -63, and mortality [53]

X

    

Self-rated quality of life

In general, how would you rate your overall quality of life in the past week (5-pt Likert)

1

Test-retest coefficient = 0.81 [54]

X

    

Comorbid illness

Determined by ICD-9 codes (chart)

0

Mortality c-stat: [23]

 

X

   

Charlson comorbidity score [24]

Charlson = 0.704

Elixhauser comorbidity score [55]

Elixhauser = 0.793

Social support

Modified Medical Outcomes Study Social Support (mMOS-SS)

11

Cronbach’s α = 0.88-.93 [56]

 

X

   

Religion/spirituality

Self-reported extent of how spiritual/religious (5-pt Likert) and role play in decision-making.

4

Spirituality associated with quality of life. Religiosity associated with wanting all measures to extend life [57]

 

X

   

Prior ACP experience

Prior ACP experiences (for example, Ever had to make life threatening medical decisions?”) [12]

5

  

X

   

Major life changes

For example, “In the past 6 months, have you or someone close to you been faced with a serious medical problem or diagnosis?”

4

     

X

 

Mediator variablesa (also measured as Outcome Variables)

       

Baseline knowledge

Knowledge subscales of the ACP Engagement Survey.

6

Cronbach’s α = 0.84 (0.76-0.90), ICC = 0.70 (0.50-0.82) [15]

 

X

   

Baseline self-efficacy

Self-efficacy subscales of the ACP Engagement Survey.

6

Cronbach’s α = 0.83 (0.75-0.89), ICC = 0.60 (0.41-0.76) [15]

 

X

   

Baseline readiness

Readiness subscales of the ACP Engagement Survey.

10

Cronbach’s α = 0.92 (0.88-0.95), ICC = 0.60 (0.53-0.81) [15]

 

X

   

Baseline barriers

Checkbox of 13 common barriers

13

Associated with ACP [25]

 

X

   

Baseline attitudes

Processes of Change for ACP [16]

34

Responsive to an ACP intervention [15]

 

X

   

Desired role in decision-making

Control Preference Scale (CPS) [58]

2

Correlation between preferred and actual role in decision-making [5961]

 

X

  

X

 

Primary Outcome Variables

       

Full process of ACP

ACP Engagement Survey: Process Measures of knowledge, contemplation, self-efficacy, readiness

116

Process Measures: Cronbach’s α = 0.94 (0.91-0.96), ICC = 0.70 (0.54-0.82) [15]

 

X

X

X

X

Action Measures: completion of advance directives, discussions

 

Action Measures: ICC = 0.87 (0.79-0.92) [15]

 

Secondary outcome variables

       

Communication quality

Modified CAHPS (that is, did this provider explain things in a way that was easy to understand?)

14

Comparative Fit Index = 0.98, Tucker Lewis Index = 0.98

 

X

X

  

Internal consistency: 0.58 to 0.92. ≥ 0.70 for four of eight constructs [62]

Satisfaction with communication

For example, “How satisfied are you that you could share your most important concerns with X/that X understood what was most important to you?)

8

  

X

X

X

X

Satisfaction with care

Care Consistent with Goals: Comparison of 10-point ratings about aggressiveness of care desired and care currently receiving.

4

  

X

  

X

Barriers to ACP

Checkbox of 13 common barriers (for example, thinking about the topic makes me nervous or sad; I am too healthy; I am too busy; my family or doctor is too busy; I prefer to leave my health in God’s hands; I don’t want to burden my family and friends; I want to leave the choice to my friends and family; I want to leave the choice to my doctors; and an open-category response for “other.”)

13

Associated with ACP [25]

 

X

  

X

Attitudes about ACP

Processes of change for ACP [16]

34

Responsive to ACP intervention [15]

 

X

   

Desired role in decision-making

Control Preference Scale (CPS) [58]

2

Correlation between preferred and actual role in decision-making [5961]

 

X

  

X

Satisfaction with decision making

Decisional Conflict Scale

20

test-retest coefficient = 0.81

  

X

X

X

α coefficient: 0.78-0.92 for total scale. 0.58-0.92 for subscales [31]

Depression and anxiety

Patient Health Questionnaire (PHQ-4)

4

Cronbach’s α = 0.78 [63]

 

X

X

X

X

Surrogate reports of patient engagement in ACP and other surrogate items

Modified from the ACP Engagement Survey [22], (for example, “Did [Veteran] ask you to be their surrogate decision maker, talk to you about leeway, talk to you about their values, tell other family or friends about their wishes, ask clinicians questions or have you ask clinicians questions?”

45

     

X

Prior ACP

6

Care consistent with goals

4

Decisional Conflict

19

Implementation

13

Implementation: acceptability

Acceptability and Usability

 

1 factor explained 81-85 % of variance/scale. Kuder-Richardson >0.75 [12]

 

X

   

(a) Ease of use and understanding

8

(b) Usefulness in decisions & discussions

6

(c) Attitudes about norms or expectations

6

for example, “Did you try to fill out the advance directive we gave you?” “Did you give it to a medical provider, social worker, or case manager?” If they respond no, “Why do you think you did not turn it in?” “What can we do to get other people to look over these materials?” “What would motivate them?” “What suggestions do you have to make these materials better?”

 

Implementation: feasibility

Feasibility (Control) (for example, when and where to review ACP materials)

7

     

X

Feasibility (PREPARE only) (for example, when and where to review ACP materials, and which PREPARE materials did you use and would recommend)

34

“Do you remember what your action plan was?”

 

“Did you complete your action plan?”

If no to completing an action plan, “Why do you think you have not completed your action plan?”

“After the first study visit, did you look at the (action plan, summary of your wishes, the PREPARE website, pamphlet, Booklet/or DVD) again?

 

If no, “Why do you think you didn’t you look at it?”

       

Satisfaction questions include “Which of the PREPARE materials was the most helpful?”; “Which would you use again?” “Which did you share with your decision maker, friends, or family?” “When is the best time to see the PREPARE materials?” “Where do you think most people would prefer to review the PREPARE materials (home, clinic, or public space)?

  1. aWhereas the mediator variables, measured at baseline, may explain how or why a particular effect or relationship occurs, these variables may also be affected by the intervention and are therefore also measured as outcome variables