TABLE III.
Adjusted As-Treated Analysis of Improvement from Baseline Averaged Over Four Years of Follow-up*
| Mean Improvement (Std. Error) |
||||
| Outcome Measure | Operative | Nonoperative | Treatment Effect (95% CI)† | |
| SF-36 bodily pain‡ | <80 yr | 28 (0.6) | 13.4 (0.7) | 14.6 (13.1 to 16.2) |
| ≥80 yr | 21.3 (2.2) | 13.8 (2.3) | 7.5 (2.3 to 12.8) | |
| P value | 0.004 | 0.85 | 0.01 | |
| SF-36 physical function‡ | <80 yr | 24.4 (0.6) | 11.1 (0.7) | 13.3 (11.7 to 14.8) |
| ≥80 yr | 13.4 (2.3) | 3.8 (2.4) | 9.6 (4.2 to 15) | |
| P value | <0.001 | 0.004 | 0.20 | |
| ODI§ | <80 yr | −21.3 (0.5) | −8.9 (0.6) | −12.4 (−13.6 to −11.2) |
| ≥80 yr | −18.5 (1.8) | −5.2 (1.9) | −13.3 (−17.6 to −9) | |
| P value | 0.14 | 0.06 | 0.69 | |
| Stenosis Bothersomeness Index# | <80 yr | −7.8 (0.2) | −3.6 (0.2) | −4.3 (−4.7 to −3.8) |
| ≥80 yr | −6.6 (0.6) | −3.8 (0.7) | −2.8 (−4.4 to −1.2) | |
| P value | 0.07 | 0.74 | 0.093 | |
| Low Back Pain Bothersomeness Scale** | <80 yr | −1.9 (0) | −1 (0.1) | −0.9 (−1 to −0.8) |
| ≥80 yr | −1.8 (0.2) | −1 (0.2) | −0.8 (−1.2 to −0.3) | |
| P value | 0.51 | 0.89 | 0.55 | |
| Very or somewhat satisfied with symptoms (%) | <80 yr | 65.9 | 31.8 | 34.1 (30.7 to 37.6) |
| ≥80 yr | 55.2 | 30 | 25.3 (13.6 to 37) | |
| P value | 0.029 | 0.70 | 0.15 | |
| Self-rated progress as major improvement (%) | <80 yr | 66.4 | 24.9 | 41.5 (38.3 to 44.7) |
| ≥80 yr | 54.6 | 31.1 | 23.5 (11.6 to 35.4) | |
| P value | 0.016 | 0.22 | 0.004 | |
Scores are adjusted for sex, education, income, work status, compensation, BMI, smoking status, hypertension, osteoporosis, heart problem, depression, joint problems, no. of moderate to severe stenotic levels, diagnosis, baseline score (for SF-36, ODI, and Stenosis Bothersomeness), and center. The area under the curve was used to calculate the average result over the four-year follow-up period.
The treatment effect is the difference between the operative and nonoperative mean change from baseline.
The SF-36 score can range from 0 to 100, with a higher score indicating less severe symptoms.
The ODI can range from 0 to 100, with a lower score indicating less severe symptoms.
The Stenosis Bothersomeness Index can range from 0 to 24, with a lower score indicating less severe symptoms.
The Low Back Pain Bothersomeness Scale can range from 0 to 6, with a lower score indicating less severe symptoms.