Lumbar disc herniation in the Spine Patient Outcomes Research Trial: does educational attainment impact outcome?

Abstract

Study design: Randomized trial with concurrent observational cohort. A total of 1171 patients were divided into subgroups by educational attainment: high school or less, some college, and college degree or above.

Objective: To assess the influence of education level on outcomes for treatment of lumbar disc herniation.

Summary of background data: Educational attainment has been demonstrated to have an inverse relationship with pain perception, comorbidities, and mortality.

Methods: The Spine Patient Outcomes Research Trial enrolled surgical candidates (imaging-confirmed disc herniation with at least 6 weeks of persistent signs and symptoms of radiculopathy) from 13 multidisciplinary spine clinics in 11 US states. Treatments were standard open discectomy versus nonoperative treatment. Outcomes were changes from baseline for 36-Item Short Form Health Survey (SF-36), bodily pain (BP), and physical function (PF) scales and the modified Oswestry Disability Index (ODI) at 6 weeks, 3 months, 6 months, and yearly through 4 years.

Results: Substantial improvement was seen in all patient cohorts. Surgical outcomes did not differ by level of education. For nonoperative outcomes, however, higher levels of education were associated with significantly greater overall improvement over 4 years in BP (P = 0.007), PF (P = 0.001), and ODI (P = 0.003). At 4 years a "dose-response" type relationship was shown for BP (high school or less = 25.5, some college = 31, and college graduate or above = 36.3, P = 0.004) and results were similar for PF and ODI. The success of nonoperative treatment in the more educated cohort resulted in an attenuation of the relative benefit of surgery.

Conclusion: Patients with higher educational attainment demonstrated significantly greater improvement with nonoperative treatment while educational attainment was not associated with surgical outcomes.

Trial registration: ClinicalTrials.gov NCT00000410.

Figures

Figure 1

Primary outcomes over time for ‘High school or less’, ‘Some college’ and ‘College grad or above’.

1. The surgery p-value compares ‘High school or less,’ ‘Some college’ and ‘College grad or above’ among Surgery patients.

2. The non-operative p-value compares ‘High school or less,’ ‘Some college’ and ‘College grad or above’ among Non-operative patients.

3. The interaction p-value compares treatment effect (surgery vs. non-operative) among ‘High school or less,’ ‘Some college’ and ‘College grad or above’

* P-values are time-weighted averages at 4 years (area under the curve p-values)