Table 1.
Characteristics of follow-up cohort and non-respondents (retired/drop-outs)
| Characteristics in 1996 | Follow-up cohort (actively working participants, n = 360) | Retired or dropout due to non-response (n = 465) |
|---|---|---|
| Age (years), mean ± SD | 35.7 ± 5.4 | 41.6 ± 9.0 |
| Age group [n (%)] | ||
| <30 | 46 (13) | 60 (13) |
| 30‒40 | 219 (61) | 130 (28) |
| >40 | 95 (26) | 275 (59) |
| Work experience (years) mean ± SD | 12.3 ± 5.3 | 17.3 + 8.2 |
| Working hours [n (%)] | ||
| 24-h shift work | 265 (74) | 375 (81) |
| Other kind of shift work | 62 (17) | 58 (13) |
| Regular daytime work | 24 (7) | 22 (5) |
| Other | 8 (2) | 7 (1) |
| Sleep disturbances [n (%)] | ||
| None | 208 (58) | 235 (51) |
| Mild | 137 (38) | 194 (42) |
| Severe | 14 (4) | 33 (7) |
| Radiating low back pain [n (%)] | 53 (16) | 77 (19) |
| Local low back pain [n (%)] | 95 (28) | 111 (26) |
| Musculoskeletal pain in body parts other than back [n (%)] | 207 (58) | 265 (58) |
| Smoking [n (%)] | ||
| Never smoker | 74 (21) | 75 (16) |
| Ex-smoker | 117 (33) | 112 (24) |
| Current smoker | 168 (47) | 277 (60) |
| Physical workload sum index (0–12) [n (%)] | ||
| <6 | 121 (34) | 132 (29) |
| 6‒7 | 140 (39) | 186 (42) |
| 8‒12 | 97 (27) | 129 (29) |
| Number of work accidents during last 3 years [n (%)] | ||
| 0 | 43 (20) | 47 (19) |
| 1 | 61 (28) | 74 (29) |
| 2 | 51 (24) | 61 (24) |
| >2 | 60 (28) | 71 (28) |
| Psychosocial job demands sum index (0‒16) [n (%)] | ||
| None (0) | 108 (30) | 113 (24) |
| Few (1‒4) | 193 (54) | 226 (49) |
| Some (5‒8) | 48 (13) | 101 (22) |
| Many/very many (9‒16) | 11 (3) | 22 (5) |