Appendix. Non-Significant Bivariate Associations (P ≥ 0.10) of Baseline Variables with Clinically
Significant Weight Gain (7%) by One Year after Initial Occupational Back Injury
Domain and variables
Sociodemographic
Age, years (ref= 35-44 years)
≤24 years
25 – 34 years
45 – 54 years
≥ 55 years
Region of worker residence † (ref=urban)
Suburban
Large town
Rural
Race/ethnicity (ref=White non-Hispanic)
Hispanic
Other
Education (ref=high school)
Less than high school
Vocational or some college
College
Marital status (ref=married/living with partner)
Other
Employment-related
Worker’s industry ‡ (ref=trade/transportation)
Natural resources
Construction
Manufacturing
Management
Education and health
Hospitality
Heavy lifting (ref=not at all/rarely/occasionally)
Frequently
Constantly
Whole body vibration (ref=not at all/rarely)
Occasionally/frequently
Constantly
Physical demands (ref=sedentary/light)
Medium
Heavy
Very heavy
Excessive amount of work (ref=strongly
No significant
weight gain
N=1089
Significant
Odds
weight gain
ratio^
N=174
339
94
244
289
123
633
184
124
115
798
142
149
364
120
495
110
748
340
53
17
50
43
11
97
33
22
20
122
30
22
58
14
84
18
114
60
285
49
201
83
192
155
124
510
363
215
708
254
125
211
357
257
258
871
39
6
27
8
26
36
32
83
51
39
127
34
13
43
47
44
39
134
95% CI
P-value
0.14
1.16
1.31
0.95
0.57
0.64 – 2.09
0.86 – 1.99
0.62 – 1.47
0.29 – 1.13
0.64
1.17
1.14
1.12
0.75 – 1.80
0.68 – 1.89
0.66 – 1.90
0.34
1.35
0.88
0.86 – 2.11
0.54 – 1.45
0.68
0.73
1.05
1.00
0.39 – 1.36
0.73 – 1.52
0.56 – 1.78
1.05
0.74 – 1.48
0.97
1.11
0.75
0.96
1.25
1.56
0.38 – 2.43
0.65 – 1.89
0.34 – 1.68
0.56 – 1.64
0.73 – 2.14
0.92 – 2.65
0.78
0.57
0.42
0.90
1.19
0.61 – 1.32
0.78 – 1.83
0.46
0.94
0.74
0.61 – 1.46
0.40 – 1.39
0.49
0.69
0.99
0.85
0.44 – 1.09
0.61 – 1.59
0.52 – 1.40
0.21
disagree/disagree)
Strongly agree/agree
Enough time to do job (ref=Strongly
agree/agree)
Strongly disagree/disagree
Very hectic (ref=Strongly disagree/disagree)
Agree
Strongly agree
Supervisor listens to my work problems
(ref=agree)
Strongly disagree/disagree
Strongly agree
Satisfaction with job (ref=Somewhat or very
satisfied)
Not at all or not too satisfied
Co-worker relations (0 – 10 scale, ref=10, get
along extremely well)
8–9
0–7
Job type at time of injury (ref=full-time)
Part-time
Seasonal job at injury (ref=no)
Yes
Temporary job at injury (ref=no)
Yes
Job duration ≥ 6 months
< 6 months
Employer offered job accommodation (ref=Yes)
No
Pain and function
Number pain sites (ref=0-2 sites)
3 – 4 sites
5 – 8 sites
Pain intensity, past week (0= no pain, ref= 0–
3)41
4–5
6–7
8 – 10
Pain interference with work, past week (0=no
interference, ref=0-3)41
4–5
6–7
8 – 10
Roland questionnaire € (0=no disability) (ref=0-
218
796
40
117
1.12
0.94 – 1.32
293
313
494
279
622
57
39
85
49
101
1.22
0.86 – 1.73
1.30
1.12
0.86 – 1.96
0.70 – 1.78
205
248
944
40
30
149
1.03
0.67
142
570
25
90
1.02
394
121
992
97
1020
68
1024
62
865
222
517
561
67
16
158
15
167
7
163
11
135
39
75
94
1.07
0.86
528
403
158
291
70
74
30
41
289
286
223
405
43
48
42
52
0.99
1.07
1.24
189
192
300
326
29
33
59
47
1.20
1.35
1.52
0.26
0.60
0.25
0.69 – 1.56
0.43 – 1.04
0.30
0.64 – 1.64
0.87
0.75 – 1.51
0.48 – 1.53
0.26
0.71
0.39 – 1.29
0.35
0.68
0.30 – 1.52
1.23
0.63 – 2.41
0.55
0.67
1.09
0.73 – 1.62
0.15
1.28
0.92 – 1.79
0.21
1.37
1.29
0.96 – 1.97
0.80 – 2.09
0.79
0.62 – 1.58
0.68 – 1.68
0.77 – 1.99
0.32
0.74 – 1.97
0.84 – 2.18
1.00 – 2.29
0.23
8)43
9 – 16
17 – 24
SF-36 v2 Physical Function ¶ (ref=>50)40
41 – 50
30 – 40
< 30
SF-36 v2 Role Physical ¶ (ref=>50)40
30 – 50
< 30
Pain change since injury (ref=better)
Same
Worse
Clinical status
Injury severity †† (ref=mild strain/sprain)11
Major strain/sprain with substantial
immobility but no evidence of radiculopathy
Evidence of radiculopathy or abnormalities
Pain radiates below knee (ref=no)
Yes
Previous similar back injury (ref=no)
Yes
Previous injury (any type) with ≥ 1 month off
work (ref=no)
Yes
Number of self-reported worker’s
compensation claims before current injury
(ref=0)
1
2–3
≥4
Work days missed because of back, previous
year (ref=0)
1 – 10
> 10
Work days missed because of other health
problems, previous year (ref=0)
1 – 10
> 10
Number other major medical problems (ref=0)
≥1
General health, year prior to injury
(ref=excellent)
Very good
386
377
276
209
279
325
239
469
381
762
198
120
53
74
39
27
42
66
37
63
74
111
42
19
594
215
91
36
273
791
298
568
521
791
0.95
1.30
0.62 – 1.45
0.87 – 1.95
0.26
0.93
1.03
1.40
0.55 – 1.57
0.64 – 1.66
0.90 – 2.18
0.11
0.82
1.22
0.53 – 1.28
0.79 – 1.90
0.49
1.36
1.00
0.92 – 2.02
0.59 – 1.71
1.07
0.70 – 1.63
47
119
55
101
73
128
1.15
0.78 – 1.70
295
402
46
64
1.14
328
236
115
720
49
40
18
114
1.06
1.31
1.33
269
87
458
39
16
56
0.92
1.31
536
78
906
182
262
98
14
147
27
33
1.34
1.26
415
62
1.16
0.31
0.27
1.22
0.86 – 1.74
0.94
0.67 – 1.32
0.73
0.49
0.78 – 1.67
0.40
0.70 – 1.60
0.84 – 2.04
0.74 – 2.39
0.34
0.62 – 1.37
0.73 – 2.33
0.20
0.94 – 1.91
0.66 – 2.40
0.99
1.00
0.63 – 1.60
0.23
0.74 – 1.83
Good
320
58
1.39 0.88 – 2.21
Fair/poor
90
21
1.71 0.93 – 3.13
Opioid Rx within 6 weeks of injury (ref=no)
703
109
Yes
359
59
1.07 0.76 – 1.52
Health care
Health care provider recommended exercise
768
126
(ref=yes)
No
319
48
0.92 0.64 – 1.33
Health insurance (ref=yes)
787
119
No
301
54
1.13 0.79 – 1.62
Administrative/legal
Time from injury to first medical visit for injury
845
123
◊ (ref=0-6 days)
7 – 13 days
119
26
1.66 1.03 – 2.66
≥ 14 days
96
18
1.33 0.77 – 2.30
Health behavior
Tobacco use (ref=no)
591
92
Occasionally/frequently
166
23
0.90 0.55 – 1.48
Daily
332
59
1.14 0.80 – 1.63
Alcohol Use Disorder Identification Test755
129
Consumption (AUDIT-C)^^ (ref=negative,
AUDIT-C score of 0 – 3 for males, 0 – 2 for
females)42
Positive (4 – 12 for males, 3 – 12 for
331
44
0.77 0.53 – 1.12
females)
Baseline Body Mass Index (BMI) (ref=<25)
318
57
25 – 29 (overweight)
443
63
0.92 0.62 – 1.37
≥ 30 (obese)
328
54
1.00 0.67 – 1.51
Psychological
Blame for injury40 (ref=work)
527
91
Self
230
27
0.72 0.45 – 1.14
Someone/something else
151
30
1.11 0.70 – 1.75
Nothing/no one
160
21
0.80 0.48 – 1.33
Work fear-avoidance (ref= <3, very low) ◊◊
214
28
Low-moderate (>3 – <5)
358
51
1.11 0.68 – 1.82
High (5 – 6)
517
95
1.37 0.87 – 2.15
Missing, “don’t know,” and refusal responses for each variable were combined into one
response for each variable (results not shown)
Ref indicates reference group.
All measures were obtained from worker baseline interviews except where noted
^ All odds ratios were adjusted for age and gender, except for age
0.64
0.66
0.32
0.12
0.63
0.30
0.89
0.41
0.31
† By residential zip code, using the Washington State guidelines classifications at
http://www.doh.wa.gov/Data/Guidelines/RuralUrban
‡ Derived from Standard Industrial Codes (SIC)
€ Roland-Morris Disability Questionnaire assesses overall back disability43-45
¶ Scores from the Short-Form-36 version 2 (SF-36v2) Physical Function and Role Physical scales;
higher scores indicate better functioning40
†† Rated by trained nurses based on medical records early in the claim
◊ From worker’s compensation database
^^ The AUDIT-C score is a screening test for problematic alcohol usage42
◊◊ Mean of responses to two questions from the Fear-Avoidance Beliefs Questionnaire work
scale47