Surgical versus nonoperative treatment for lumbar disc herniation: eight-year results for the spine patient outcomes research trial

Abstract

Study design: Concurrent prospective randomized and observational cohort studies.

Objective: To assess the 8-year outcomes of surgery versus nonoperative care.

Summary of background data: Although randomized trials have demonstrated small short-term differences in favor of surgery, long-term outcomes comparing surgical with nonoperative treatment remain controversial.

Methods: Surgical candidates with imaging-confirmed lumbar intervertebral disc herniation meeting Spine Patient Outcomes Research Trial eligibility criteria enrolled into prospective randomized (501 participants) and observational cohorts (743 participants) at 13 spine clinics in 11 US states. Interventions were standard open discectomy versus usual nonoperative care. Main outcome measures were changes from baseline in the SF-36 Bodily Pain and Physical Function scales and the modified Oswestry Disability Index-AAOS/Modems version assessed at 6 weeks, 3 months, and 6 months, and annually thereafter.

Results: Advantages were seen for surgery in intent-to-treat analyses for the randomized cohort for all primary and secondary outcomes other than work status; however, with extensive nonadherence to treatment assignment (49% patients assigned to nonoperative therapy receiving surgery versus 60% of patients assigned to surgery) these observed effects were relatively small and not statistically significant for primary outcomes (bodily pain, physical function, Oswestry Disability Index). Importantly, the overall comparison of secondary outcomes was significantly greater with surgery in the intent-to-treat analysis (sciatica bothersomeness [P > 0.005], satisfaction with symptoms [P > 0.013], and self-rated improvement [P > 0.013]) in long-term follow-up. An as-treated analysis showed significant surgical treatment effects for primary outcome measures (mean change, surgery vs. nonoperative care; treatment effect; 95% confidence interval): bodily pain (45.3 vs. 34.4; 10.9; 7.7 to 14); PF (42.2 vs. 31.5; 10.6; 7.7 to 13.5); and Oswestry Disability Index (-36.2 vs. -24.8; -11.3; -13.6 to -9.1).

Conclusion: Carefully selected patients who underwent surgery for a lumbar disc herniation achieved greater improvement than nonoperatively treated patients; there was little to no degradation of outcomes in either group (operative and nonoperative) from 4 to 8 years.

Level of evidence: 2.

Figure 1. Exclusion, Enrollment, Randomization and Follow-up of Trial Participants

The values for surgery, withdrawal, and death are cumulative over 8 years. For example, a total of 1 patient in the group assigned to surgery died during the 4-year follow-up period. [Data set 04/10/2008]

Figure 2. Primary Outcomes (SF-36 Bodily Pain and Physical Function, and Oswestry Disability Index) in the Randomized and Observational Cohorts during 8 Years of Follow-up

The graphs show both the intent-to-treat and the as-treated analyses for the randomized cohort (column on the left) and the as-treated analysis for the observation cohort (column on the right). The horizontal dashed line in each of the 4 SF-36 graphics represents normal values adjusted for age and sex. The vertical bars represent 95% confidence intervals. At 0 months, the floating data points represent the observed baseline mean scores for each study group, whereas the data points on plot lines represent the estimated means from the the adjusted analyses.

Figure 3. Secondary Outcomes (Sciatica Bothersomeness, Satisfaction with Symptoms, and Self-rated Global Improvement) in the Randomized and Observational Cohorts during 8 Years of Follow-up

The graphs show both the intent-to-treat and the as-treated analyses for the randomized cohort (column on the left) and the as-treated analysis for the observation cohort (column on the right). The vertical bars represent 95% confidence intervals. At 0 months, the floating data points represent the observed baseline mean scores for each study group, whereas the data points on plot lines represent the estimated means from the adjusted analyses.