Table 1.
Characteristics of participants at baseline (n=3142) and 12-months follow-up (2022), including number of missing values in each of the variables
| Characteristics and domain | Baseline (n=3142) |
Complete sample (n=2022) |
|---|---|---|
| Sociodemographic | ||
| Female gender, n (%) | 1502 (47.8) | 1005 (49.7) |
| Age, mean years (SD) | 49.5 (9.3) | 51.0 (9.2) |
| Age <40 | 404 (12.9) | 189 (9.4) |
| Age 40-60 | 2355 (75.0) | 1534 (75.9) |
| Age >60 | 380 (12.1) | 298 (14.7) |
| Missing | 3 (0) | 1 (0) |
| Work status prior to operation, n (%) | ||
| Student, in work or at home | 974 (31.4) | 187 (9.3) |
| Retired or disability pension | 460 (14.8) | 334 (16.6) |
| Rehabilitation pension | 278 (9.0) | 157 (7.8) |
| Sick leave | 1390 (44.8) | 1333 (66.3) |
| Missing | 40 (1.3) | 11 (0.5) |
| Physical demands in work, n (%) | ||
| Working in front of a computer/sitting still | 1039 (38.8) | 712 (41.6) |
| Light physical work | 486 (18.1) | 319 (18.6) |
| Hard physical work | 1156 (43.1) | 681 (39.8) |
| Missing | 461 (14.7) | 310 (15.5) |
| Educational level, n (%) | ||
| High school or less | 1963 (64.1) | 1231 (62.3) |
| Less than 4 years of university | 626 (20.5) | 405 (20.5) |
| 4 or more years of university | 472 (15.4) | 339 (17.2) |
| Missing | 81 (2.5) | 47 (2.3) |
| Non-native speaker, n (%) | 229 (7.3) | 134 (6.6) |
| Missing | 2 (0) | 2 (0) |
| Pending litigation1, n (%) | ||
| No | 2764 (89.0) | 1680 (83.1) |
| Yes | 342 (11.0) | 342 (16.9) |
| Missing | 36 (1.1) | 0 (0) |
| Physical/somatic | ||
| Obesity (Body Mass Index ≥ 30), n (%) | 657 (21.4) | 419 (21.2) |
| Missing | 78 (2.5) | 48 (2.4) |
| Smoking | 1043 (33.9) | 582 (29.4) |
| Missing | 63 (2.0) | 40 (2.0) |
| Comorbidity | 1272 (40.5) | 842 (41.6) |
| Missing | 0 (0) | 0 (0) |
| Previous neck surgery (same level) | 265 (8.6) | 160 (8.1) |
| Missing | 52 (1.7) | 40 (2.0) |
| Number of surgical levels | ||
| One level | 2347 (75.3) | 1488 (74.4) |
| Two or more levels | 768 (24.7) | 512 (25.6) |
| Missing | 27 (0.9) | 22 (1.0) |
| Type of surgery | ||
| Anterior discectomy and fusion | 3109 (98.9) | 2003 (99.0) |
| Anterior discectomy and arthroplasty | 33 (1.1) | 19 (1.0) |
| Missing | 0 (0) | 0 (0) |
| Clinical self-report | ||
| Duration of arm pain | ||
| < 3 months | 440 (14.4) | 284 (14.4) |
| 3-12 months | 1120 (36.7) | 714 (36.2) |
| > 1 year | 1494 (48.9) | 975 (49.4) |
| Missing | 88 (2.8) | 49 (2.4) |
| Duration of pre-operative paresis | ||
| No paresis | 641 (22.6) | 425 (22.4) |
| < 3 months | 450 (15.8) | 357 (18.8) |
| 3 months or more | 1750 (61.6) | 1116 (58.8) |
| Missing | 301 (9.6) | 124 (6.1) |
| Daily use of analgetic drugs (vs < daily use) | 1634 (52.8) | 1042 (52.4) |
| Missing | 48 (1.5) | 25 (1.2) |
| ASA level of 3 or more2 | 151 (5.0) | 101 (5.2) |
| Missing | 99 (3.2) | 76 (3.8) |
| Arm pain worse than neck pain | 945 (32.0) | 591 (31.2) |
| Missing | 187 (6.0) | 125 (6.1) |
| Baseline neck pain (NRS3), mean (SD) | 6.1 (2.5) | 6.1 (2.5) |
| Baseline arm pain (NRS3), mean (SD) | 6.4 (2.4) | 6.4 (2.4) |
| Baseline disability (NDI4), mean (SD) | 41.6 (15.1) | 41.0 (15.2) |
| Psychological | ||
| Anxiety or depression5 | 1355 (44.0) | 832 (41.8) |
| Missing | 62 (2.0) | 31 (1.0) |
1Pending medical claim/litigation against the Norwegian public welfare agency fund concerning disability pension or pending medical compensation claim/litigation against private insurance companies or the public Norwegian System of Compensation to Patients. 2American Society of Anesthesiologists grade. 3Numeric rating scale (0-10). 4Neck Disability Index, 0-100 (no-maximal disability). 5Based on scoring “moderate” or “extremely” anxious or depressed in the item in EQ-5D-3L questionnaire