TABLE I.
Baseline Characteristics by Herniation Level in the Spine Patient Outcomes Research Trial (SPORT) Intervertebral Disc Herniation Randomized Cohort and Observation Cohort Combined*
| L2-L3 and L3-L4 (N = 88) | L4-L5 (N= 456) | L5-S1 (N = 646) | Overall P Value† | |
|---|---|---|---|---|
| Demographics and health status | ||||
| Male patients | 54 (61%) | 275 (60%) | 354 (55%) | 0.14 |
| Age‡(yr) | 50.9 ± 10.9 | 41.8 ± 12.1 | 40.4 ± 10.3 | <0.001 |
| Body mass index‡ | 28.4 ± 6.2 | 28.2 ± 5.3 | 27.8 ± 5.6 | 0.35 |
| Height‡(ft [m]) | 5.7 ± 0.3 (1.7 ± 0.09) | 5.7 ± 0.3 (1.7 ± 0.09) | 5.7 ± 0.3 (1.7 ± 0.09) | 0.56 |
| Patients who were smokers | 20 (23%) | 112 (25%) | 149 (23%) | 0.85 |
| Patients who worked | 40 (45%) | 288 (63%) | 417 (65%) | 0.002 |
| Workers' Compensation status | 0.66 | |||
| None | 75 (85%) | 371 (81%) | 534 (83%) | |
| Receiving or pending | 13 (15%) | 84 (18%) | 110 (17%) | |
| Cohort | 0.093 | |||
| Randomized | 32 (36%) | 165 (36%) | 274 (42%) | |
| Observation | 56 (64%) | 291 (64%) | 372 (58%) | |
| Duration of symptoms | 0.20 | |||
| ≤6 wk | 14 (16%) | 68 (15%) | 83 (13%) | |
| 1.5 to 6 mo | 55 (63%) | 275 (60%) | 434 (67%) | |
| >6 mo | 19 (22%) | 113 (25%) | 129 (20%) | |
| Days to surgery‡ | 50.4 ± 194 | 84 ± 260.2 | 62.5 ± 161.9 | 0.31 |
| SF-36 bodily pain score‡ | 29.3 ± 18.5 | 25.6 ± 19.4 | 25.6 ± 17.2 | 0.20 |
| SF-36 physical functioning score‡ | 35.1 ± 22.8 | 38 ± 26.4 | 37.9 ± 25.3 | 0.59 |
| Oswestry Disability Index score‡ | 46.8 ± 20.1 | 50 ± 21.8 | 49.5 ± 21.1 | 0.42 |
| Leg symptom severity score‡ | 13.9 ± 5.3 | 15.4 ± 5.3 | 15.9 ± 5.2 | 0.003 |
| Clinical findings (no. of patients) | ||||
| Pain radiation | 87 (99%) | 444 (97%) | 629 (97%) | 0.69 |
| Straight leg-raising test—ipsilateral | 22 (25%) | 262 (57%) | 465 (72%) | <0.001 |
| Straight leg-raising test—contralateral or both | 2 (2%) | 92 (20%) | 94 (15%) | <0.001 |
| Any femoral tension sign | 38 (43%) | 34 (7%) | 17 (3%) | <0.001 |
| Any neurological deficit | 67 (76%) | 338 (74%) | 496 (77%) | 0.58 |
| Asymmetric depressed reflexes | 34 (39%) | 95 (21%) | 351 (54%) | <0.001 |
| Asymmetric decreased sensory changes | 42 (48%) | 241 (53%) | 320 (50%) | 0.50 |
| Asymmetric motor weakness | 39 (44%) | 219 (48%) | 243 (38%) | 0.002 |
| Herniation type | <0.001 | |||
| Protruding | 15 (17%) | 119 (26%) | 188 (29%) | |
| Extruded | 54 (61%) | 309 (68%) | 419 (65%) | |
| Sequestered | 19 (22%) | 28 (6%) | 39 (6%) | |
| Posterolateral herniation | 39 (44%) | 345 (76%) | 534 (83%) | <0.001 |
*
Includes only patients who had follow-up data available for the two-year outcomes analysis.
†
P values are based on chi-square tests for categorical variables and on analysis of variance for continuous variables.
‡
The values are given as the mean and the standard deviation.