Correlation between severity of preoperative low back pain and postoperative outcomes in lumbar disc herniation surgery: a retrospective cohort study.

Background context: Low back pain (LBP) frequently occurs in patients with lumbar disc herniation (LDH), however the extent to which discectomy ameliorates it and how preoperative LBP influences postoperative outcomes remains unclear.

Purpose: To evaluate the improvement in LBP and its impact on postoperative patient-reported outcome measures (PROMs).

Study design/setting: Multicenter retrospective observational study.

Patient sample: Patients undergoing discectomy for LDH at 8 hospitals from April 2017 to March 2021.

Outcome measures: Data were collected on patients' backgrounds, operative factors, and PROMs, including the Numeric Rating Scale (NRS) for pain in the low back, buttock, or leg, EuroQol 5 Dimension (EQ-5D), Oswestry Disability Index (ODI) scores, and postoperative satisfaction.

Methods: Patients were categorized into mild (NRS 0-3), moderate (NRS 4-7), or severe (NRS 8-10) LBP groups. Inverse probability weighting with propensity scores was used to adjust for demographic and clinical differences between groups. Chi-square tests and one-way analysis of variance were conducted to compare background data and clinical characteristics. Additionally, multivariate logistic regression was performed to identify risk factors for less than 50% improvement in LBP.

Results: This study included 928 patients: 270 mild, 343 moderate, and 315 severe. After adjustment, preoperative NRS scores were significantly different across groups, with scores of 1.6 (SD 1.3), 5.6 (SD 1.0), and 8.8 (SD 0.9), respectively. Postoperative NRS scores also varied significantly, with worse outcomes observed in the severe group compared to the mild group, yet similar to the moderate group. A total of 46.8% of the mild group, 86.6% of the moderate group, and 72.9% of the severe group achieved a 50% decrease in NRS scores of LBP. Preoperative EQ-5D and ODI scores were significantly worse in the severe group compared to the mild or moderate groups, but postoperative scores were not significantly different between the severe and moderate groups. No significant differences in postoperative satisfaction were observed among the groups. Being female was a significant risk factor for less than 50% improvement in LBP (odds ratio = 1.56, p=.022).

Conclusions: Discectomy significantly improved LBP in patients with LDH, including those with moderate or severe LBP. Patients with severe LBP showed similar improvements in PROMs as those with moderate LBP. Female gender emerged as a significant risk factor for less than optimal improvement in LBP.