Does reduction in sciatica symptoms precede improvement in disability and physical health among those treated surgically for intervertebral disc herniation? Analysis of temporal patterns in data from the Spine Patient Outcomes Research Trial

Background context: Pain, pain-related disability, and functional limitations are common consequences of intervertebral disc herniation (IDH). We hypothesized that surgical treatment reduces pain, leading to improvement in pain-related disability and, ultimately, better physical health.

Purpose: The present study aims to evaluate pathways for improvements in quality of life during the first year after surgery for IDH by studying temporal relationships between sciatica symptoms, pain-related disability, and physical health.

Design: This is a secondary analysis of a randomized controlled trial using an "as treated" dataset.

Patient sample: The sample comprised 803 patients in the Spine Patient Outcomes Research Trial.

Outcome measures: We used the Sciatica Bothersome Index, Oswestry Disability Index, and the Medical Outcomes Study Short Form 36 physical component score.

Methods: We included 803 patients in the Spine Patient Outcomes Research Trial who underwent elective decompressive surgery for IDH between 2000 and 2004. Sciatica, pain-related disability, and physical health were assessed preoperatively and at 3 and 12 months postoperatively using the Sciatica Bothersome Index, Oswestry Disability Index, and Medical Outcomes Study Short Form 36 physical component score, respectively. Temporal associations of improvement in sciatica with pain-related disability and physical health were assessed using cross-lagged path analysis. p<.05 was considered significant. No funding was received in support of the present study. The authors declare no conflicts of interest.

Results: Preoperatively, mean scores were 16.2±5.2 for sciatica, 54.2±20.7 for pain-related disability, and 29.8±8.4 for physical health. After adjustment for patient age and symptom duration, cross-lagged path analysis showed that sciatica reduction at 3 months was correlated with pain-related disability reduction at 3 months (ρ=.76, p<.001), and pain-related disability at 3 months was predictive of physical health at 12 months (β=-.33, p<.001) and sciatica at 12 months (β=.22, p<.001).

Conclusion: Three months after surgery, patients reported reduced sciatica and pain-related disability. Improvements in pain and pain-related disability occurred within 3 months. Early reduction in pain-related disability is important because path analysis indicated that disability at 3 months was predictive of sciatica and physical health at 1 year.