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Table 2 Endorsement frequencies and Mokken scalability (Loevinger’s H i coefficients) for the 9 items of the Shared Decision-Making Questionnaire (SDM-Q-9)

From: Psychometric properties of the SDM-Q-9 questionnaire for shared decision-making in multiple sclerosis: item response theory modelling and confirmatory factor analysis

Item number and content

Mean (SD)

Endorsement frequencies (%)

H i

  

1

2

3

4

5

6

 

1. A decision needs to be made

5.19 (1.37)

14 (6)

4 (2)

3 (0.01)

18 (0.08)

49 (0.22)

135 (0.60)

0.27

2. How I want to be involved

5.17 (1.23)

7 (3)

5 (2)

7 (0.03)

31 (0.14)

46 (0.21)

127 (0.57)

0.60

3. Informing me different options are available

5.53 (1.12)

8 (4)

2 (1)

4 (0.02)

8 (0.04)

29 (0.13)

172 (0.77)

0.58

4. Explaining me advantages and disadvantages

5.57 (1.00)

5 (2)

2 (1)

3 (0.01)

12 (0.05)

31 (0.14)

170 (0.76)

0.59

5. Helping me to understand the information

5.63 (0.86)

4 (2)

0 (0)

2 (0.01)

10 (0.04)

37 (0.17)

170 (0.76)

0.54

6. Asking the treatment option I prefer

5.07 (1.46)

12 (5)

10 (4)

10 (0.04)

19 (0.08)

40 (0.18)

132 (0.59)

0.63

7. Weighing jointly the different options

5.13 (1.37)

11 (5)

8 (4)

4 (0.02)

25 (0.11)

46 (0.21)

129 (0.58)

0.66

8. Selecting a treatment option together

5.04 (1.41)

13 (6)

7 (3)

6 (0.03)

28 (0.13)

48 (0.21)

121 (0.54)

0.66

9. Agreeing on how to proceed

5.30 (1.23)

7 (3)

8 (4)

5 (0.02)

10 (0.04)

53 (0.24)

140 (0.63)

0.61

  1. The overall scalability (H) is 0.57. Endorsement frequencies: 1 completely disagree; 2 strongly disagree; 3 somewhat disagree; 4 somewhat agree; 5 strongly agree; 6 completely agree