Background
Method
Study population
Data collection
Baseline questionnaire
Physical examination
Frequent prospective measurements on musculoskeletal pain intensity
Inclusion/exclusion criteria
Data analyses
Statistical analyses
Pain variables | Mean | (SD) | Range |
---|---|---|---|
Accumulated LBPa | 32.5 | (28.8) | 0–137 |
Mean LBP | 2.4 | (2.1) | 0–9.8 |
Median LBP | 2.1 | (2.3) | 0–10 |
LBP > 2 | 5.5 | (5.1) | 0–14 |
LBP > 4 | 2.9 | (4.1) | 0–14 |
LBP = 0 | 5.2 | (5.2) | 0–14 |
Standard deviation | 1.3 | (0.8) | 0–4.3 |
Variation spanb | 4.2 | (2.7) | 0–10 |
Results
Study population
Descriptive characteristics |
n
| Mean (SD) or % |
---|---|---|
Age (Years), mean (SD) | 842 | 45 (9.3) |
Gender (% male) | 842 | 51 |
Country of birth (% Denmark) | 825 | 94 |
Sector (%) | 842 | |
Manufacturing | 602 | 72 |
Cleaning | 164 | 19 |
Transport | 76 | 9 |
Position (%blue-collar) | 842 | 82 |
Seniority (Years), mean (SD) | 816 | 13.3 (10.2) |
Work ability (1–10)a, mean (SD) | 837 | 8.4 (1.5) |
Physical strain at work (0–10)a, mean (SD) | 813 | 5.3 (2.4) |
BMI (kg/m2), mean (SD) | 821 | 27 (4.8) |
Back endurance (Sec.)b, mean (SD) | 544 | 106 (56.8) |
LBP intensity baseline (0–10), mean (SD) | 837 | 3.3 (3) |
Grouping of the pain variables using factor and correlation analyses
Accumulated LBP | Mean LBP | Median LBP | LBP >2 | LBP >4 | LBP =0 | Standard Deviation | Variation span | |
---|---|---|---|---|---|---|---|---|
Accumulated LBP | 1 | - | - | - | - | - | - | - |
Mean LBP | 0.99 | 1 | - | - | - | - | - | - |
Median LBP | 0.97 | 0.98 | 1 | - | - | - | - | - |
LBP > 2 | 0.94 | 0.93 | 0.91 | 1 | - | - | - | - |
LBP > 4 | 0.92 | 0.92 | 0.89 | 0.81 | 1 | - | - | - |
LBP = 0 | −0.81 | −0.81 | −0.79 | −0.80 | −0.57 | 1 | - | - |
Standard deviation | 0.42 | 0.42 | 0.31 | 0.38 | 0.32 | −0.42 | 1 | - |
Variation span | 0.43 | 0.43 | 0.33 | 0.40 | 0.32 | −0.46 | 0.96 | 1 |
Visual pain mapping
Low intensity Low variation | Low intensity High variation | High intensity High variation | High intensity Low variation | ||
---|---|---|---|---|---|
n = 287 (34 %) | n = 216 (26 %) | n = 182 (22 %) | n = 157 (19 %) | ||
n
| % | % | % | % | |
Age (years), mean (SD) | 842 | 45 (9) | 44 (10) | 46 (9) | 47 (9) |
Gender | 842 | ||||
Male | 430 | 36 | 27 | 20 | 18 |
Female | 412 | 32 | 24 | 24 | 20 |
Sector | 842 | ||||
Manufacturing | 602 | 35 | 26 | 22 | 18 |
Cleaning | 164 | 30 | 23 | 24 | 23 |
Transport | 76 | 37 | 30 | 14 | 18 |
Position | 842 | ||||
Blue-collar | 693 | 32 | 25 | 22 | 21 |
White-collar | 149 | 44 | 30 | 19 | 7 |
Seniority | 816 | ||||
0–5 years | 178 | 34 | 29 | 19 | 17 |
5–10 years | 192 | 33 | 30 | 20 | 16 |
10–20 years | 220 | 35 | 22 | 26 | 17 |
> 20 years | 226 | 34 | 23 | 20 | 23 |
Workabilitya | 842 | ||||
9–10 | 468 | 43 | 26 | 19 | 12 |
8 | 211 | 29 | 25 | 24 | 22 |
0–7 | 163 | 15 | 26 | 26 | 33 |
Physical strain at worka | 813 | ||||
1–3 | 224 | 42 | 29 | 18 | 11 |
4–7 | 415 | 35 | 24 | 21 | 20 |
8–10 | 174 | 22 | 25 | 28 | 25 |
BMI (kg/m2) | 842 | ||||
< 25 | 306 | 36 | 26 | 18 | 20 |
25–30 | 320 | 35 | 25 | 22 | 18 |
> 30 | 216 | 30 | 26 | 26 | 18 |
Back enduranceb | 842 | ||||
= > 90 sec | 326 | 45 | 28 | 16 | 11 |
46–89 sec | 89 | 27 | 38 | 17 | 18 |
11–45 sec | 124 | 33 | 28 | 19 | 20 |
< 10 sec | 303 | 25 | 18 | 30 | 27 |
LBP intensity baseline | 837 | ||||
0 | 257 | 61 | 27 | 7 | 5 |
1–4 | 295 | 36 | 28 | 20 | 15 |
5–7 | 175 | 11 | 25 | 30 | 34 |
8–10 | 110 | 2 | 18 | 47 | 33 |
Baseline risk factors for chronic LBP
Model 1 | Model 2 | Model 3 | |||||
---|---|---|---|---|---|---|---|
Demographic factors |
n
| OR (95 % CI) | P-value | OR (95 % CI) | P-value | OR (95 % CI) | P-value |
Age (years) | 842 | 1.03 (1.00–1.05) |
0.01
| 1.03 (1.01–1.05) |
0.01
| 1.01 (0.99–1.04) | 0.29 |
Gender | 842 | ||||||
Male | 430 | REF | REF | REF | |||
Female | 412 | 1.14 (0.81–1.61) | 0.46 | 1.08 (0.76–1.54) | 0.65 | 1.17 (0.75–1.83) | 0.49 |
Sector | 842 | ||||||
Manufacturing | 602 | REF | REF | REF | |||
Cleaning | 164 | 1.36 (0.89–2.08) | 0.25 | 1.25 (0.79–1.98) | 0.46 | 1.05 (0.63–1.77) | 0.83 |
Transport | 76 | 1.06 (0.57–1.96) | 0.75 | 1.04 (0.55–1.98) | 0.83 | 0.97 (0.47–2.01) | 0.89 |
Position | 842 | ||||||
Blue-collar | 693 | REF | REF | REF | |||
White-collar | 149 | 0.30 (0.16–0.57) |
<.01
| 0.30 (0.16–0.56) |
<.01
| 0.46 (0.21–0.99) |
<0.05
|
Seniority | 816 | ||||||
0–5 years | 178 | REF | REF | REF | |||
5–10 years | 192 | 0.91 (0.53–1.58) | 0.41 | 0.88 (0.51–1.52) | 0.60 | 0.92 (0.50–1.68) | 0.54 |
10–20 years | 220 | 0.96 (0.57–1.62) | 0.57 | 0.85 (0.50–1.45) | 0.45 | 0.90 (0.49–1.64) | 0.45 |
> 20 years | 226 | 1.38 (0.84–2.27) | 0.06 | 1.13 (0.66–1.93) | 0.30 | 1.34 (0.72–2.48) | 0.14 |
Workability | 842 | ||||||
9–10 | 469 | REF | REF | REF | |||
8 | 211 | 2.11 (1.37–3.23) | 0.62 | 2.11 (1.38–3.25) | 0.59 | 1.70 (1.06–2.71) | 0.68 |
0–7 | 163 | 3.65 (2.37–5.60) |
<.01
| 3.61 (2.34–5.56) |
<.01
| 2.41 (1.49–3.89) |
<0.01
|
Physical strain at work | 813 | ||||||
1–3 | 224 | REF | REF | REF | |||
4–7 | 415 | 2.05 (1.26–3.34) | 0.25 | 2.06 (1.27–3.37) | 0.22 | 1.17 (0.64–2.12) | 0.93 |
8–10 | 174 | 2.74 (1.59–4.72) |
<.01
| 2.69 (1.55–4.67) |
<.01
| 1.41 (0.72–2.77) | 0.29 |
BMI (kg/m2) | 842 | ||||||
< 25 | 306 | REF | REF | REF | |||
25–30 | 320 | 0.91 (0.61–1.36) | 0.80 | 0.90 (0.60–1.34) | 0.80 | 0.73 (0.46–1.15) | 0.96 |
> 30 | 216 | 0.90 (0.58–1.41) | 0.79 | 0.88 (0.56–1.38) | 0.72 | 0.54 (0.32–0.90) |
<0.05
|
Back endurance | 842 | ||||||
= > 90 sec | 326 | REF | REF | REF | |||
46–89 sec | 89 | 1.82 (0.96–3.47) | 0.95 | 1.80 (0.94–3.43) | 0.99 | 1.56 (0.78–3.12) | 0.91 |
11–45 sec | 124 | 2.10 (1.20–3.68) | 0.50 | 2.05 (1.17–3.61) | 0.48 | 1.76 (0.93–3.35) | 0.48 |
< 10 sec | 303 | 3.03 (1.97–4.68) |
<.01
| 2.81 (1.80–4.39) |
<.01
| 1.92 (1.16–3.19) | 0.14 |
LBP intensity baseline | 837 | ||||||
0 | 257 | REF | REF | REF | |||
1–4 | 295 | 3.12 (1.76–5.84) | 0.14 | 3.26 (1.74–6.10) | 0.19 | 3.28 (1.71–6.27) | 0.57 |
5–7 | 175 | 9.06 (4.86–16.88) |
<.01
| 9.24 (4.95–17.27) |
<.01
| 7.85 (4.11–14.99) |
<.01
|
8–10 | 110 | 8.44 (4.32–16.50) |
<.01
| 8.40 (4.29–16.46) |
<.01
| 6.52 (3.19–13.33) |
<.01
|