Intravenous Lidocaine Does Not Provide Additional Pain Reduction Beyond Placebo in Probable Nociplastic Chronic Low...

To evaluate whether repeated intravenous lidocaine infusions provide clinically meaningful benefit beyond placebo for pain reduction in probable nociplastic chronic non-specific low back pain.

In this prospective, randomized, double-blind, placebo-controlled equivalence trial, 84 adults with CNSLBP and probable nociplastic pain features were randomized equally to receive either intravenous lidocaine (1 mg/kg bolus followed by 4 mg/kg infusion weekly for 4 weeks) or placebo saline infusion. All participants received background multimodal pain management consisting of amitriptyline and aerobic exercise. The primary endpoint was the between-group difference in VAS pain intensity at 3 months. Therapeutic equivalence was assessed using a prespecified equivalence margin of ± 1.5 VAS units and the two one-sided tests (TOST) framework. Secondary outcomes included sleep quality (PSQI) and functional disability (QBPDS).

At 3 months, the between-group difference in VAS was 0.24 (90% confidence interval -0.33 to 0.81), entirely within the predefined equivalence bounds, confirming therapeutic equivalence (TOST p < 0.001). Both groups improved significantly over time without a significant group × time interaction. Improvement in sleep quality was greater in the lidocaine group (mean difference in change score 1.81; 95% CI 0.49-3.14; p = 0.027). Functional improvement numerically favored lidocaine, although continuous disability outcomes were not significantly different. Adverse events were more common in the lidocaine group but were mild, transient, and self-limiting.

Repeated intravenous lidocaine infusions did not provide additional analgesic benefit over saline infusions administered alongside multimodal pain management in patients with probable nociplastic chronic non-specific low back pain.