PAIN+ CPN

OBJECTIVE: 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.

METHODS: 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).

RESULTS: 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.

CONCLUSION: 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.

Dr. Michelle O'Brien (9/8/2026 8:08 AM)

Variable outcomes due to different and non-standardised dosing regimes.