Table 1 Frequencies of demographic, work and health factors in the 5556 Swedish individual twins with Lower Back Pain (LBP), Neck and/or Shoulder Pain (NSP), stratified on sex
|  | All (N = 5556) | Men (n = 2193) | Women (n = 3363) |
|---|---|---|---|
n (%) | n (%) | n (%) | |
Age group | |||
 19–28 | 905 (16.3) | 339 (15.5) | 566 (16.8) |
 29–37 | 1946 (35.0) | 765 (34.9) | 1181 (35.1) |
 38–47 | 2705 (48.7) | 1089 (49.7) | 1616 (48.1) |
Education | |||
 Primary | 370 (6.7) | 183 (8.3) | 187 (5.6) |
 Secondary | 2557 (46.0) | 1138 (51.9) | 1419 (42.2) |
 Higher | 2245 (40.4) | 774 (35.3) | 1471 (43.7) |
 Missing | 384 (6.9) | 98 (4.5) | 286 (8.5) |
Back pain | |||
 LBP | 1576 (28.4) | 821 (37.4) | 755 (22.5) |
 NSP | 2518 (45.3) | 872 (39.8) | 1646 (48.9) |
 LBP & NSP | 1462 (26.3) | 500 (22.8) | 962 (28.6) |
MDD/GAD | |||
 No | 3940 (70.9) | 1740 (79.3) | 2200 (65.4) |
 Yes | 661 (11.9) | 165 (7.5) | 496 (14.7) |
 Missing | 955 (17.2) | 288 (13.1) | 667 (19.8) |
Self-rated health | |||
 Excellent | 1241 (22.3) | 540 (24.6) | 701 (20.8) |
 Good | 2856 (51.4) | 1136 (51.8) | 1720 (51.1) |
 Moderate | 1235 (22.2) | 445 (20.3) | 790 (23.5) |
 Not good/Poor | 222 (4.0) | 72 (3.3) | 150 (4.5) |
 Missing | 2 (0) | 0 (0) | 2 (0.1) |
Physical activity | |||
 None/low | 921 (16.6) | 346 (15.8) | 575 (17.1) |
 Moderate | 1262 (22.7) | 402 (18.3) | 860 (25.6) |
 High | 1529 (27.5) | 533 (24.3) | 996 (29.6) |
 Vigourous | 773 (13.9) | 333 (15.2) | 440 (13.1) |
 Missing | 1071 (19.3) | 579 (26.4) | 492 (14.6) |
Regular analgesia | |||
 No | 3243 (58.4) | 1550 (70.7) | 1693 (50.3) |
 Yes | 2309 (41.6) | 642 (29.3) | 1667 (49.6) |
 Missing | 4 (0.1) | 1 (0) | 3 (0.1) |
 Mean job demands | 2.4 (SD 0.6) | 2.4 (SD 0.6) | 2.4 (SD 0.6) |
 Mean job control | 2.0 (SD 0.6) | 1.9 (SD 0.6) | 2.0 (SD 0.6) |
 Mean job Support | 1.7 (SD 0.5) | 1.7 (SD 0.5) | 1.7 (SD 0.5) |
Work environment | |||
 Low strain | 1223 (22.0) | 506 (23.1) | 717 (21.3) |
 Passive | 900 (16.2) | 332 (15.1) | 568 (16.9) |
 Active | 1891 (34.0) | 819 (37.3) | 1072 (31.9) |
 Strain | 438 (7.9) | 155 (7.1) | 283 (8.4) |
 Iso-strain | 698 (12.6) | 230 (10.5) | 468 (13.9) |
 Missing | 406 (7.3) | 151 (6.9) | 255 (7.6) |
Sick leave > 90 net days or disability pension | |||
 Yes | 761 (13.7) | 207 (9.4) | 554 (16.5) |
 No | 4795 (86.3) | 1986 (90.6) | 2809 (83.5) |
Unemployment > 90 days | |||
 No | 4954 (89.2) | 1978 (90.2) | 2976 (88.5) |
 Yes | 602 (10.8) | 215 (9.8) | 387 (11.5) |