To Örebro University

Background and purpose: Indication for lumbar disc herniation (LDH) surgery is usually to relieve sciatica. We evaluated whether back pain also decreases after LDH surgery.

Patients and methods: In the Swedish register for spinal surgery (SweSpine) we identified 14,097 patients aged 20-64 years, with pre- and postoperative data, who in 2000-2016 had LDH surgery. We calculated 1-year improvement on numeric rating scale (rating 0-10) in back pain (N_back) and leg pain (N_leg) and by negative binomial regression relative risk (RR) for gaining improvement exceeding minimum clinically important difference (MCID).

Results: N_leg was preoperatively (mean [SD]) 6.7 (2.5) and N_back was 4.7 (2.9) (p < 0.001). Surgery reduced N_leg by mean 4.5 (95% CI 4.5-4.6) and N_back by 2.2 (CI 2.1-2.2). Mean reduction in N_leg) was 67% and in N_back 47% (p < 0.001). Among patients with preoperative pain ≥ MCID (that is, patients with significant baseline pain and with a theoretical possibility to improve above MCID), the proportion who reached improvement ≥ MCID was 79% in N_leg and 60% in N_back. RR for gaining improvement ≥ MCID in smokers compared with non-smokers was for N_leg 0.9 (CI 0.8-0.9) and -N_back 0.9 (CI 0.8-0.9), and in patients with preoperative duration of back pain 0-3 months compared with > 24 months for N_leg 1.3 (CI 1.2-1.5) and for N_back 1.4 (CI 1.2-1.5).

Interpretation: LDH surgery improves leg pain more than back pain; nevertheless, 60% of the patients with significant back pain improved ≥ MCID. Smoking and long duration of pain is associated with inferior recovery in both N_leg and N_back.