Prognostic factors associated with best outcomes (minimal symptom state) following fusion for lumbar degenerative conditions

Abstract

Background context: Previous studies suggest that a postoperative symptom state with Oswestry Disability Index (ODI)≤20 and pain Numeric Rating Scales (NRS)≤2 following surgery for lumbar degenerative conditions are reasonable thresholds for best outcomes in which patients will be unlikely to seek additional medical care or require additional health-care resources.

Purpose: To identify prognostic factors that predict a "best outcome," defined as postoperative ODI≤20 and pain NRS≤2 following fusion for lumbar degenerative conditions.

Study design: Longitudinal observational cohort.

Patient sample: A total of 396 patients from a single site enrolled in the Quality Outcomes Database who underwent fusion for lumbar degenerative conditions.

Outcome measures: Oswestry Disability Index, Back and Leg Pain NRS (0-10).

Methods: Collected and analyzed variables included age, sex, body mass index, American Society of Anesthesia grade, number of surgical levels, surgical time, preoperative ODI, preoperative back pain, preoperative leg pain, workmen compensation status, surgical approach, smoking status, and principal diagnosis.

Results: A total of 74 patients (19%) reported a minimal symptom state at 1-year postoperative (ODI≤20, back pain NRS≤2, and leg pain NRS≤2) and were included in the best outcomes group. Patients in the best outcomes group were older (62 vs. 57 years, p=.001), had lower preoperative ODI (43 vs. 56, p=.000), lower preoperative back pain (6.5 vs. 7.5, p=.000). They had fewer surgical levels (1.25 vs. 1.47, p=.005) and shorter operative times [OR] times (208 vs. 241 minutes, p=.002). They were more likely to have a preoperative diagnosis of spondylolisthesis or disc herniation and less likely to have a diagnosis of adjacent segment disease or mechanical disc collapse (p=.001). Stepwise forward regression analysis revealed diagnosis (p=.023, OR=0.75), age (p=.000, OR=1.04), baseline ODI (p=.000, OR=0.96), and number of levels (p=.019, OR=0.53) as predictive variables.

Conclusion: Achieving a minimal symptom state, defined here as a postoperative ODI≤20 and pain NRS≤2, following fusion for lumbar degenerative conditions is more likely in an older patient with a lower baseline ODI undergoing a single level lumbar fusion for spondylolisthesis.

Keywords: Back pain; Best outcomes; Lumbar degenerative disorders; Lumbar fusion; Oswestry Disability Index; Patient reported outcomes.