Both translators (WF and MLN) and the reviewer (CB) did not differ much in their translations of the items as well as the response scale. Translation differences were found for the introduction (how to best translate the word “skills”) as well as single items, namely item 2 (agenda vs. themes), item 7 (adding e.g., to the examples), item 8 (by using a German synonym for empathy), item 11 (the word “shared” was translated differently) and item 12 (the word “assuring” was translated differently). Additionally, the response format word for “not relevant” differed between both translators. In summary, only the choice of single words differed between the translators without differences in meaning (e.g. the word “patient” also represents the word “client”, which is often used in psycho-oncology, psycho-social and psychotherapy settings). Within the first round of team discussion (adjudication process) all authors reached consensus on a final version.
To test the German version of the SE-12 for comprehensibility, cognitive interviews with n = 6 HCPs (n = 2 physicians, n = 2 nurses, n = 2 psychologists; 50% being female) were conducted by assessing the complete evaluation tool developed for the pilot-study (Johannsen et al 2023). Cognitive interviews for the complete 13-page baseline questionnaire including a series of measurements lasted for about 75 minutes each. As participants had no critical feedback or comprehensibility issues on the instructions and items of the SE-12-G, no further adaptions to the final version were necessary. The final SE-12-G measure used in this study can be found in the Additional file 1, the English version is displayed in Table 3.
Sample characteristics
Data of n = 152 participants were included in this secondary data analysis. The mean age was 44.4 years (SD 11.6) with 88% being female. Most of the participants were psychologists (37.5%), followed by physicians (26.3%), nurses (18.4%) and social workers/others (17.8%). Of their professional experience working with cancer patients, most had > 11 years of experience (39.1%), followed by 1–5 years (30.5%), 6–10 years (21.9%) and 8.6% less than 1 year (see Table 2).
Table 2
Sample characteristics at baseline (t0, n = 152)
|
Total
(n = 152)
|
Age, M (SD) [range]
|
44.42 (11.6) [24–71]
|
Sex, n (%)
|
|
female
|
134 (88.2)
|
male
|
18 (11.8)
|
Professional group, n (%)
|
|
Physician
|
40 (26.3)
|
Nurse
|
28 (18.4)
|
Psychologist
|
57 (37.5)
|
Social Worker/Other
|
27 (17.8)
|
Workplace setting†, n (%)
|
|
outpatient
|
94 (61.8)
|
inpatient
|
84 (55.3)
|
self-employed/registered
|
25 (16.4)
|
other
|
8 (5.3)
|
Working experience with cancer patients, n (%)
|
|
< 1 year
|
13 (8.6)
|
1–5 years
|
46 (30.5)
|
6–10 years
|
33 (21.9)
|
> 11 years
|
59 (39.1)
|
Amount of cancer patients per month, No. M (SD) [range], %
|
67.4 (33.0) [.1-100], n = 143
|
Amount of cancer patients between 25–55 years old, M (SD) [range] in %
|
37.52 (22.21) [.1-100], n = 131
|
Amount of cancer patients parenting minor children, M (SD) [range] in %
|
21.4 (21.9) [0-100], n = 123
|
Marital status, n (%)
|
|
single
|
54 (35.8)
|
married
|
82 (54.3)
|
separated/divorced
|
11 (7.3)
|
registered partnership
|
1 (0.7)
|
widowed
|
3 (1.9)
|
Participants having children, n (%)
|
97 (63.8)
|
Having participated in communication skills trainings before, n (%)
|
134 (88.2)
|
Abbreviations. M: Mean, SD: Standard Deviation; †Multiple answers possible
SE-12-G item analysis
Table 3 shows response distribution, distribution of participants with highest score (floor effects), acceptance, corrected item-total correlation and item difficulty of the 12 items.
Depending on the item, between 5.3% and 6.6% of the participants rated the respective item as “not relevant”. Missing values ranged from 1.3-2% per item. Considering all items, participants answered more than 98% of the SE-12-G.
Ceiling effects were present, for the confidence-scale in 6 of the 12 items (items 3, 4, 5, 7, 8, 10) with a range from 15.8% (item 10) to 30.3% (item 8) of respondents, exceeding the >15% set as limit (41) and therefore indicating high ceiling effects. Regarding the importance-scale, all 12 items present ceiling effects with a range from 54.6% (item 9 and 11) to 85.5% (item 8).
Corrected item-total correlation values for the confidence-scale ranged from 0.46 (item 4) to 0.66 (item 3), for the importance-scale values ranged from 0.34 (item 1) to 0.62 (item 10) with Items 3 for the confidence-scale and item 10 for the importance-scale suggesting stronger relationships between the items and the construct. In contrast, item 4 for the confidence-scale and item 1 for the importance-scale indicate weaker associations with the construct with correlation values of <0.30.
The mean item difficulty (Table 3) across all items was 0.79 for the confidence-scale (range 0.71-0.87) and 0.91 for the importance-scale (range 0.84-0.97) indicating that, on average, items tended to be relatively easy for participants.
[add Table 3 around here]
Inter-item correlations (Table 4) for the confidence-scale ranged from 0.019 (item 4 and item 11) to 0.733 (item 3 and item 5), for the importance-scale from 0.044 (item 5 and item 8) to 0.533 (item 2 and item 10), indicating that item 4 and 11 lack coherence.
[add Table 4 around here]
Internal consistency and test-retest reliability
Cronbach’s alpha coefficient for SE-12-G was high with a calculated α of 0.88 for the confidence-scale and α 0.83 for the importance-scale.
The test-retest reliability at item level for the two subscales was good with estimated correlation coefficient for the 12 items for the confidence-scale being r=0.725 with a 95% Bootstrap Confidence Interval (BCI) of 0.484-0.874 and for the importance-scale estimated correlations of r=0.726 with a 95% BCI of 0.479-0.862 (Table 5). For the confidence-scale no item showed a weak correlation, 5 items showed a moderate correlation of 0.430-0.491 (item 2, 3, 7, 11, 12) and 6 items showed strong correlations ranging from 0.538-0.755 (item 1, 4, 5, 6, 8, 9, 10). For the importance-scale, two items had a strong correlation (item 4 r=0.605, item 5 r=0.632), 8 items a moderate correlation ranging from 0.327-0.421 (item 1, 2, 3, 7, 8, 9, 10, 12) and two items a weak correlation (item 6 r=0.160, item 11 r=0.226).
[add Table 5 around here]
Convergent validity
Statistically significant but weak correlations were found between the confidence-scale and the items working experience in general (r=0.203**, range 0.043-0.350) and working experience with cancer patients (r=0.147**, range 0.085-0.406). No significant correlations were found for the importance-scale for working experience in general (r=.035, range -0.116-0.191) and working experience with cancer patients (r=0.147, range -0.093-0.250).
Responsiveness to change
The Cohen’s d for the confidence-scale was 0.77 (95% CI [4.0, 5.5]), indicating a moderate to large effect size, suggesting responsiveness for change after an intervention (Table 6). For the importance-scale Cohen’s d was 0.25 (95% CI [-.167, .275]) indicating a small effect, suggesting that this subscale shows limited sensitivity in detecting changes over time.
Table 6. Responsiveness to change
|
N†
|
Mdiff (SD) [95% CI]
|
T
|
df
|
p
|
d [CI 95%]
|
Scale
|
Confidence-scale t1-t0
|
80
|
3.68 (0.77) [3.5, 3.8]
|
42.727
|
79
|
< 0.000
|
0.77 [4.0;5.5]
|
Importance-scale t1-t0
|
79
|
0.01 (0.25) [-0.4, 0.07]
|
0.475
|
78
|
0.636
|
0.25 [-.167,.275]
|
Abbreviations: † Intervention participants only (face-to-face and E-Learning, two measurement points, baseline (t0) and after-training participation (t1); Mdiff, mean difference (t1-t0); SD, Standard Difference; CI, Confidence Interval; T, df, degrees of freedom; p, p-value; d, Cohen’s d effect.
Discriminant validity
Analyses of group differences between HCP groups revealed statistically significant differences among the groups for several items of the confidence-scale (e.g., urge the patient to express his or her problems/worries, listen attentively to the patient, demonstrate appropriate non-verbal behavior, show empathy, make a plan based on shared decisions) and for two items in the importance subscale (listen attentively to the patient, encourage the patient to express thoughts and feelings). Most differences were between physicians and psychologists as well as nurses and psychologists with psychologists scoring higher in self-efficacy (Table 7).
[add Table 7 around here]
Factor analysis
Requirements for factor analysis were met, with an adequate sample size of n=149 HCPs related to the indicators per factor (47), after three cases were excluded due to >30% missing items. Additionally, further requirements were met, with KMO measure at .0.843 and Bartlett’s test of sphericity yielding X²=829.190, p<.001 (33) (34). Model fit indices of the three a priori models are presented in Table 8. Factor reliability was satisfactory for all three models (M1: ω 0.827; M2: ω 0.891; M3a: ω 0.839 confidence and ω 0.882 importance), and factor loadings for all 12 items for both subscales were medium to high (M1: between 0.477 and 0.799 for the confidence-scale only; M2: 0.395-0.751 for both subscales; M3a: 0.405-0.810 for both subscales; M3b: 0.410-0.837)(see Figure 1 for M3b and Additional file 2 for figures of M1-3a), indicating that the presented items (communication skills) measure the underlying construct (confidence in and importance of these skills). Factor covariance for M2 and M3a was 0.426 and for M3b 0.432, indicating a moderate correlation between the two factors, affirming their distinctness as separate constructs.
[add Figure 1 around here]
Figure 1. Confirmatory factor analysis model for one-factorial structure (model 3b)
Regarding the model fit indices, values indicated a suboptimal fit of the three assumed models (Table 8). The convergent validity of all three models was low, with higher, but still inadequate AVE values for M3a and M3b for both factors (Table 8), indicating that the latent constructs do not adequately capture the variance in its observed indicators (38).
Table 8. Fit indices for the SE-12-G questionnaire.
Model
|
χ2
|
df
|
P value
|
CFI
|
TLI
|
RMSEA [90% CI]
|
SRMR
|
AVE
|
M1
|
268.346
|
54
|
<.001
|
0.712
|
0.648
|
0.163
|
0.106
|
0.364
|
M2
|
579.761
|
239
|
<.001
|
0.776
|
0.741
|
0.097
|
0.092
|
C: 0.396
I: 0.331
|
M3a
|
366.631
|
235
|
<.001
|
0.888
|
0.868
|
0.061
|
0.098
|
C: 0.357
I: 0.497
|
M3b
|
376.144
|
235
|
<.001
|
0.880
|
0.859
|
0.063
|
0.099
|
C: 0.359
I: 0.489
|
Note: M1 = Axboe et al Model, only confidence-scale; M2 = The model which included confidence- and importance-scale for each 12 items applying continuous variables; M3a = The model which included confidence- and importance-scale for each 12 items, applying ordinal variables for the importance-scale; M3b = like M3a but additional modifications for assumed residual covariances for items 3 and 5 as well as 9 and 10.
Abbreviations: χ2, chi-square; df, degrees of freedom; AVE, average variance extracted; CFI, comparative fit index; CI, confidence interval; RMSEA, root mean square error of approximation; SRMR, standardized root mean square residual; TLI, Tucker–Lewis index.