Baseline characteristics of disability pension (DP) applicants and non-applicants and type of surgery performed
| DP-applicants | Non-applicants | P value | |
| Age,* mean (95% CI) | 50.0 (49.3 to 50.7) | 47.5 (47.3 to 47.6) | <0.001 |
| Missing, n (%) | 0 | 0 | |
| Female gender,* n (%) | 423 (52.5) | 6341 (41.5) | <0.001 |
| Missing | 0 | 0 | |
| Smokers,* n (%) | 262 (32.5) | 3111 (20.3) | <0.001 |
| Missing | 8 (1.0) | 131 (0.9) | |
| College or university education,* n (%) | 206 (25.6) | 6600 (43.2) | <0.001 |
| Missing | 9 (1.1) | 70 (0.5) | |
| Native Norwegian speaker,* n (%) | 692 (85.9) | 14 125 (92.4) | <0.001 |
| Missing | 4 (0.5) | 42 (0.3) | |
| Body mass index,* mean (95% CI) | 28.2 (27.9 to 28.6) | 27.2 (27.1 to 27.2) | <0.001 |
| Missing | 29 (3.6) | 372 (2.4) | |
| Numeric Rating Scale for back pain,* mean (95% CI) | 7.2 (7.0 to 7.3) | 6.2 (6.1 to 6.2) | <0.001 |
| Missing, n (%) | 14 (1.7) | 363 (2.4) | |
| Numeric Rating Scale for leg pain,* mean (95% CI) | 6.9 (6.8 to 7.1) | 6.5 (6.5 to 6.5) | <0.001 |
| Missing, n (%) | 21 (2.6) | 373 (2.4) | |
| Oswestry Disability Index,* mean (95% CI) | 48.6 (47.4 to 49.8) | 42.0 (41.7 to 42.3) | <0.001 |
| Missing, n (%) | 3 (0.4) | 82 (0.5) | |
| EuroQoL 5 Dimensions 3 Level,* mean (95% CI) | 0.22 (0.19 to 0.25) | 0.33 (0.32 to 0.34) | <0.001 |
| Missing, n (%) | 155 (19.2) | 2863 (18.7) | |
| Duration of back pain,* n (%) | <0.001 | ||
| No symptoms | 9 (1.1) | 311 (2.0) | |
| Less than 3 months | 47 (5.8) | 1994 (13.0) | |
| 3–12 months | 164 (20.3) | 5660 (37.0) | |
| 12–24 months | 141 (17.5) | 2381 (15.6) | |
| More than 24 months | 426 (52.9) | 4681 (30.6) | |
| Missing | 19 (2.4) | 264 (1.7) | |
| Duration of radiating pain,* n (%) | <0.001 | ||
| No symptoms | 19 (2.4) | 440 (2.9) | |
| Less than 3 months | 73 (9.1) | 2871 (18.8) | |
| 3–12 months | 215 (26.7) | 6379 (41.1) | |
| 12–24 months | 167 (20.7) | 2334 (15.3) | |
| More than 24 months | 299 (37.1) | 2860 (18.7) | |
| Missing | 33 (4.1) | 407 (2.7) | |
| Using painkillers,* n (%) | 732 (90.8) | 12 569 (82.2) | <0.001 |
| Missing | 6 (0.7) | 109 (0.7) | |
| Previously operated in the lumbar spine,* n (%) | 319 (39.6) | 3409 (22.3) | <0.001 |
| Missing | 3 (0.4) | 104 (0.7) | |
| Surgeon reported comorbidity,* n (%) | 400 (49.6) | 4415 (28.9) | <0.001 |
| Missing | 68 (8.4) | 1183 (7.7) | |
| American Society of Anesthesiologists′ classification,* n (%) | <0.001 | ||
| I and II | 732 (90.8) | 14 602 (95.5) | |
| III and IV | 65 (8.1) | 523 (3.4) | |
| Missing | 9 (1.1) | 166 (1.1) | |
| Moderate to severe anxiety/depression,*‡ n (%) | 418 (61.1) | 4836 (37.5) | <0.001 |
| Missing | 16 (2.3) | 239 (1.9) | |
| Duration of sick leave,* n (%) | <0.001 | ||
| Less than 3 months | 50 (6.2) | 3866 (25.3) | |
| 3–12 months | 24 (3.0) | 1235 (8.1) | |
| 12–24 months | 81 (10.0) | 1013 (6.6) | |
| More than 24 months | 160 (19.9) | 632 (4.1) | |
| Not answered (/not receiving SB) | 491 (60.9) | 8545 (55.9) | |
| Reading/writing difficulties,† n (%) | 27 (22.1) | 218 (9.0) | <0.001 |
| Missing | 6 (4.9) | 86 (3.6) | |
| Wanted back to work by employer,†§ n (%) | <0.001 | ||
| Yes | 51 (41.8) | 2004 (83.1) | |
| Uncertain | 33 (27.0) | 155 (6.4) | |
| No | 21 (17.2) | 71 (2.9) | |
| Missing | 17 (13.9) | 182 (7.5) | |
| Heavy physical work† (0–10), mean (95% CI) | 5.9 (5.2 to 6.5) | 4.4 (4.2 to 4.5) | <0.001 |
| Missing, n (%) | 26 (21.3) | 132 (5.5) | |
| Örebro Musculoskeletal Pain Questionnaire (ÖMPQ) | |||
| ÖMPQ item no 15†¶ (0–10), mean (95% CI) | 6.9 (6.4 to 7.4) | 5.6 (5.5 to 5.7) | 0.022 |
| Missing, n (%) | 12 (9.8) | 162 (6.7) | |
| ÖMPQ item no 16†** (0–10), mean (95% CI) | 3.6 (3.0 to 4.2) | 7.8 (7.7 to 8.0) | <0.001 |
| Missing, n (%) | 11 (9.0) | 114 (4.7) | |
| ÖMPQ item no 19† ††(0–10), mean (95% CI) | 7.7 (7.2 to 8.2) | 7.2 (7.1 to 7.3) | 0.164 |
| Missing, n (%) | 12 (9.8) | 119 (4.9) | |
| ÖMPQ item no 20†‡‡ (0–10), mean (95% CI) | 8.4 (7.9 to 8.9) | 6.9 (6.7 to 7.0) | <0.001 |
| Missing, n (%) | 18 (14.8) | 129 (5.3) | |
| Type of surgery performed n (%) | |||
| Lumbar disc surgery | 320 (39.7) | 9251 (60.5) | <0.001 |
| Microdecompression | 229 (28.4) | 3575 (23.4) | |
| Laminectomy | 26 (3.2) | 285 (1.9) | |
| Fusion surgery | 185 (23.0) | 1808 (11.8) | |
| Disc prosthesis | 20 (2.5) | 224 (1.5) | |
| Other types of surgery | 26 (3.2) | 148 (1.0) | |
| Missing | 0 (0.0) | 0 (0.0) | |
*Variables from 2009–2020: n=806 DP-applicants, n=15291 non-applicants.
†Variables available from 2019–2020 only: n=122 DP-applicants, n=2412 non-applicants.
‡EQ-5D fifth item.
§'Do you feel that your employer wants you back to work?’.
¶ ‘In your view, how large is the risk that your current pain may become persistent?’ (no risk-very large risk).
**'In your estimation, what are the chances you will be working your normal duties in 6 months’ (no change-very large chance).
††'An increase in pain is an indication that I should stop what I’m doing until the pain decreases’ (completely disagree-completely agree).
‡‡'I should not do my normal work with my present pain’ (completely disagree-completely agree).
EQ-5D, EuroQol 5 Dimensions.