Sample characteristics
Among the participants, 88.1% were male, 54.5% were over 45 years old, 84.2% had more than a high-school education, 45.5% worked in manufacturing, 54.5% were craft or machine operator and assemblers, 65.3% were regular workers, and 70.3% worked in small- or medium-sized organizations. Before the interview, 31.7% had been absent from work for around 4-6 months and 23.8% had been for 7-9 months, with total participants at an average of 7 months of sickness absence. Fractures represented the largest portion (61.4%) of primary injuries, followed by cartilage or tendon rupture (23.8%). More than half of the participants had injured their lower extremities (47.5%), spine (45.0%), or upper extremities (30.7%) (Table 1).
The characteristics were comparable to the descriptive statistics with first wave of data from second cohort of panel study of worker`s compensation insurance (PSWCI) organized by KCOMWEL. PSWCI is an open data source with a representative sample of 3,294 participants. The population of 75,392 injured workers who had completed medical care and benefit in 2017 stratified by gender, age, region, grade of disability and recovery service used. We selected those who had been evaluated for RTW, because they aligned closest to our inclusion criteria of participants, and we compared this with our study’s sample. When comparing the two samples, those who had been evaluated to RTW among all workers with work-related injuries, the proportion of men, college graduates, large enterprise workers, manufacturing and construction workers, and those who had been absent from work for more than one year was higher in the sample of this study. This difference is due to relatively more patients with severe injury in long-term medical care in rehabilitation centers of KCOMWEL hospitals, which are more likely to be males working in manufacturing or construction industry.
Table 1. Demographic and work-related characteristics of study participants
Variable
|
Participants of this study
|
Korean Workers' Compensation statistics (%)1
|
N
|
%
|
Gender
|
|
|
|
Male
|
178
|
88.1
|
79.7
|
Female
|
24
|
11.9
|
20.3
|
Age (years)
|
|
|
|
≤39
|
47
|
23.3
|
28.8
|
40-49
|
66
|
32.7
|
24.1
|
50-59
|
72
|
35.6
|
33.1
|
≥ 60
|
17
|
8.4
|
14.1
|
Education
|
|
|
|
< High school
|
32
|
15.8
|
22.5
|
High school
|
97
|
48.0
|
50.6
|
≥ College/university
|
73
|
36.1
|
26.9
|
Occupational categories
|
|
|
|
Manufacturing
|
92
|
45.5
|
37.9
|
Wholesale/retail/accommodation/food
|
34
|
16.8
|
10.8
|
Construction
|
53
|
26.2
|
20.7
|
Others
|
23
|
11.5
|
30.6
|
Job categories
|
|
|
|
Manager/professionals/clerks
|
34
|
16.9
|
14.2
|
Craft workers/Plant, machine operators/assemblers
|
110
|
54.5
|
55.4
|
Elementary workers
|
44
|
21.8
|
18.7
|
Others
|
14
|
6.9
|
11.7
|
Employment type
|
|
|
|
Regular worker
|
132
|
65.3
|
70.3
|
Temporary worker
|
25
|
12.4
|
10.1
|
Day worker
|
43
|
21.3
|
19.4
|
Self-employed/employer
|
2
|
1.0
|
0.2
|
Organization size
|
|
|
|
Small
|
49
|
24.3
|
38.7
|
Medium
|
93
|
46.0
|
52.8
|
Large
|
57
|
28.2
|
8.5
|
Don’t know
|
3
|
1.5
|
|
Duration of sickness absence
|
|
|
|
≤ 3 months
|
22
|
10.9
|
36.8
|
3-6months
|
64
|
31.7
|
33.7
|
7-9 months
|
48
|
23.8
|
18.8
|
10-12 months
|
17
|
8.4
|
3.9
|
≥ 13 months
|
51
|
25.2
|
6.9
|
Hospital service use type
|
|
|
|
Inpatient
|
59
|
29.2
|
|
Outpatient
|
143
|
70.8
|
|
Types of main injury
|
|
|
|
Sprain and strain
|
13
|
6.4
|
|
Peripheral nerve injury only
|
5
|
2.5
|
|
Rupture of cartilage or tendon
|
48
|
23.8
|
|
Fracture
|
124
|
61.4
|
|
Amputation
|
10
|
5.0
|
|
N/A
|
2
|
1.0
|
|
Injured area of the body (more than one)
|
|
|
|
Spine
|
91
|
45.0
|
|
Upper extremities
|
62
|
30.7
|
|
Lower extremities
|
96
|
47.5
|
|
Note: 1: Those who had been evaluated for return to work with first wave of data from the second cohort of panel study of Korean Worker`s Compensation Insurance (PSWCI) in 2018
Descriptive statistics of the RTWSE-19
As shown in Table 2, the mean scores of each item of the RTWSE-19 ranged from 4.72±3.38 to 8.09±2.39. The two items with the highest mean scores were item 16 (“Could you describe to your supervisor the nature of your injury and your medical treatment”) and item 17 (“Could you discuss openly with your supervisor things that may contribute to your discomfort”) with mean scores of 8.09±2.39 and 7.97±2.48 respectively. The two items with the lowest mean scores were item 3 (“Could you change the type of work activities you do to reduce discomfort”) and item 14 (“Could you reduce your physical workload”) with mean scores of 4.72±3.38 and 4.81±3.13 respectively. Items related to the “communicating needs to others” subscale showed relatively higher mean scores, while items related to the “modifying job tasks” subscale featured relatively lower mean scores.
Evaluation of psychometric properties
Exploratory Factor Analysis. EFA models of 1–4 factors revealed that a 3-factor model was the best fit for the 19-item scale (𝑥2= 228.834, p < .000; CFI = .953; TLI = .931; RMSEA = .069; SRMR = 0.032), but low factor loading (below 0.4) was indicated for item 1 (“Could you suggest to your supervisor ways to change your work to reduce discomfort?”) and item 7 (“Could you avoid re-injury?”).
After removing two items from the item pool, EFA was conducted for 1–4 factor models. The 3-factor model of the 17-item scale demonstrated reasonable model fit, with marginal improvement of fit-index values ( = 169.401, p < .000; CFI = .963; TLI = .943; RMSEA = .068; SRMR = 0.029) compared to 3-factor model of the 19-item scale. The resulting screen test also suggested a 3-factor solution. The final model revealed 3 distinct concepts: meeting job demands (7 items); modifying job tasks (5 items); and communicating needs to others (5 items). Two items from the original 19-item scale which concerned modifying job tasks were excluded from the final model. The factor loadings for each item are presented in Table 2.
Table 2. Items summary data and final solution of an exploratory factor analysis for the RTWSE scale
RTWSE scale Item
|
Mean
|
SD
|
Factor loadings (S.E) a
|
Factor1
|
Factor2
|
Factor3
|
Meeting Job Demands
|
|
|
|
|
|
2
|
Fulfill all of your duties and responsibilities?
|
6.28
|
3.09
|
0.65(0.07)
|
0.08(0.08)
|
–0.01(0.05)
|
5
|
Meet expectations for job performance?
|
5.96
|
2.78
|
0.50(0.07)
|
0.22(0.08)
|
0.12(0.07)
|
6
|
Perform most of your daily activities at work?
|
5.55
|
2.97
|
0.70(0.06)
|
–0.04(0.08)
|
0.01(0.05)
|
9
|
Keep up with the pace at work?
|
5.37
|
2.80
|
0.94(0.04)
|
–0.08(0.08)
|
–0.08(0.07)
|
13
|
Meet your production requirements?
|
5.52
|
3.11
|
0.86(0.04)
|
0.07(0.07)
|
0.02(0.04)
|
15
|
Do everything you’re trained to do?
|
5.79
|
3.16
|
0.82(0.04)
|
0.10(0.07)
|
0.03(0.05)
|
18
|
Do your work without slowing others down?
|
5.59
|
2.91
|
0.93(0.03)
|
–0.00(0.03)
|
–0.06(0.06)
|
|
|
|
|
|
|
|
Modifying Job Tasks
|
|
|
|
|
|
1
|
Suggest to your supervisor ways to change your work to reduce discomfort?
|
5.50
|
3.14
|
|
|
|
3
|
Change the type of work activities you do to reduce discomfort?
|
4.72
|
3.38
|
–0.06(0.11)
|
0.72(0.07)
|
–0.04(0.08)
|
7
|
Avoid re-injury?
|
6.83
|
3.04
|
|
|
|
10
|
Modify the way you work to reduce discomfort?
|
5.88
|
3.17
|
0.22(0.10)
|
0.69(0.07)
|
-0.02(0.04)
|
12
|
Avoid activities that are likely to increase pain?
|
5.85
|
3.15
|
0.10(0.10)
|
0.51(0.08)
|
0.27(0.07)
|
14
|
Reduce your physical workload?
|
4.81
|
3.13
|
0.25(0.09)
|
0.58(0.07)
|
0.02(0.05)
|
19
|
Request changes in your workstation or work area to reduce discomfort?
|
5.68
|
3.28
|
–0.01(0.02)
|
0.67(0.05)
|
0.24(0.07)
|
|
|
|
|
|
|
|
Communicating Needs to Others
|
|
|
|
|
|
4
|
Explain any physical limitations you may have to your co-workers?
|
7.77
|
2.67
|
–0.08(0.08)
|
0.02(0.07)
|
0.64(0.06)
|
8
|
Get co-workers to help you with activities that might cause discomfort?
|
7.26
|
2.84
|
0.19(0.08)
|
0.30(0.08)
|
0.41(0.07)
|
11
|
Get emotional support from coworkers (such as listening or talking about your problem)?
|
7.31
|
2.66
|
0.07(0.08)
|
0.15(0.08)
|
0.53(0.07)
|
16
|
Describe to your supervisor the nature of your injury and your medical treatment?
|
8.09
|
2.39
|
–0.12(0.07)
|
–0.01(0.02)
|
0.89(0.04)
|
17
|
Discuss openly with your supervisor things that may contribute to your discomfort?
|
7.97
|
2.48
|
0.00(0.01)
|
–0.06(0.07)
|
0.95(0.04)
|
Intercorrelations of subscales. The subscales were significantly and moderately correlated: meeting job demands and modifying job tasks (r = 0.612, p < .001); meeting job demands and communicating needs (r=0.494, p<.001); and modifying job tasks and communicating needs (r = 0.501, p < .001) (table 3).
Floor and ceiling effect. No floor or ceiling effects were found for total RTWSE and subscale scores using the criteria of 15%. Regarding communicating needs RTWSE, 12.4% achieved the highest score (10), below the 15% cutoff (table 3).
Reliability. Cronbach’s alpha for all of the overall scales and subscales was satisfactory. The Cronbach's alpha for the overall RTWSE-17 was 0.925 and was 0.842 for communicating needs, 0.851 for modifying job tasks, and 0.926 for meeting job demands (Table 3).
Table 3. Descriptive statistics, floor and ceiling effects and reliability of the Korean version of RTWSE
Scale
|
Mean
|
SD
|
N (%)
at floor
|
N (%)
at ceiling
|
Cronbach’s alpha
|
Intercorrelations
|
(1)
|
(2)
|
(3)
|
Total RTWSE-17 score
|
6.20
|
1.99
|
0 (0.0)
|
3 (1.5)
|
0.925
|
.893
(<.001)
|
.842
(<.001)
|
.743
(<.001)
|
demand
|
5.72
|
2.48
|
5 (2.5)
|
8 (4.0)
|
0.926
|
1
|
.612
(<.001)
|
.494
(<.001)
|
task
|
5.39
|
2.55
|
10 (5.0)
|
7 (3.5)
|
0.851
|
|
1
|
.501
(<.001)
|
|
7.68
|
2.05
|
0 (0.0)
|
25 (12.4)
|
0.842
|
|
|
1
|
Construct validity
Significant correlations were found between fear-avoidance beliefs about physical activity (r = −0.231, p < 0.001) and work (r = −0.441, p < 0.001), SF-12 mental health (r = 0.324, p < 0.001), depression (r = −0.301, p < 0.001), and general self-efficacy (r = 0.502, p < 0.001) and RTWSE-17 scores. Current pain intensity (r= −0.028, p=.692) and SF-12 physical health (r=0.061, p=.386) showed no correlation, and the monthly average pain intensity (r= −0.150, p=0.033) showed low correlation with RTWSE-17 scores. These patterns did not differ in significance or direction when applied to the subscales of the RTWSE-17, except that physical fear-avoidance showed no correlation with modifying job tasks and communicating needs (Table 4).
Table 4. Correlations between the Korean version of RTWSE and relevant constructs
|
Total
RTWSE-17 score
|
Meeting job demands
|
Modifying job task
|
Communicating needs
|
Current Pain
|
–.028
|
( .692)
|
–.062
|
( .380)
|
–.031
|
( .664)
|
.052
|
( .463)
|
Average Pain
|
–.150
|
( .033)
|
–.196
|
( .005)
|
–.107
|
( .128)
|
–.026
|
( .713)
|
Fear avoidance, physical activity
|
–.231
|
(<.001)
|
–.301
|
(<.001)
|
–.116
|
( .101)
|
–.106
|
( .135)
|
Fear avoidance, work
|
–.441
|
(<.001)
|
–.489
|
(<.001)
|
–.300
|
(<.001)
|
–.252
|
(<.001)
|
SF12, physical Health
|
.061
|
( .386)
|
.117
|
(.096)
|
.060
|
( .400)
|
–.074
|
( .294)
|
SF12, mental Health
|
.324
|
(<.001)
|
.335
|
(<.001)
|
.179
|
(.011)
|
.282
|
(<.001)
|
Depression
|
–.301
|
(<.001)
|
–.298
|
(<.001)
|
–.140
|
( .047)
|
–.311
|
(<.001)
|
General self-efficacy
|
.502
|
(<.001)
|
.479
|
(<.001)
|
.285
|
(<.001)
|
.495
|
(<.001)
|