Table 1.
Baseline characteristics at trial entry of 695 patients having lumbar spinal fusion
| Baseline characteristics | Non-respondents 2-year follow-up (n = 177) | All patients (n = 695) |
|---|---|---|
| Age, mean (SD) | 52 (14) | 50 (13) |
| Females | 103 (58) | 423 (61) |
| Diagnosisa | ||
| Spondylolisthesis | 33 (18) | 180 (26) |
| Primary degeneration | 73 (41) | 252 (36) |
| Secondary degeneration | 72 (41) | 262 (38) |
| Duration of pain >2 years | 116 (72) | 482 (73) |
| Smokers | 79 (55) | 290 (48) |
| Occupational status | ||
| Working | 44 (25) | 206 (30) |
| Sick-listed | 41 (23) | 212 (31) |
| Retired or pensioned due to sickness | 52 (29) | 184 (26) |
| Retired or pensioned due to age | 40 (23) | 93 (13) |
| Classification of disabilityb | ||
| Slight or intermediate disability | 25 (14) | 101 (15) |
| Major disability | 49 (28) | 210 (31) |
| Major disability + emotional distress | 100 (57) | 376 (55) |
| Type of spinal fusion | ||
| Non-instrumented posterolateral | 36 (20) | 95 (14) |
| Instrumented posterolateral | 91 (52) | 373 (54) |
| Circumferential | 49 (28) | 225 (32) |
| Vertebral levels fused at index surgery >1 | 111 (63) | 375 (54) |
Values are number of patients (%) unless stated otherwise
aPrimary degeneration = no previous surgery and secondary degeneration = degeneration after previous surgery
bAccording to classification by Ozguler et al. [20]