Clinical Predictors of Pain Relief with 60-Day Peripheral Nerve Stimulation: A Multicenter Observational Study.

Background: Clinical predictors of pain relief with 60-day peripheral nerve stimulation (PNS) remained undefined. Identifying the factors associated with treatment outcomes may improve patient selection and optimize results. Objective: This study examined baseline physical activity, pain, disability, and psychological factors influencing early versus delayed response and non-response to a 60-day PNS. Methods: A prospective, multicenter, observational cohort study was conducted on 73 patients who consecutively received a 60-day PNS. Baseline assessments included pain (numeric rating scale [NRS]), disability (Oswestry Disability Index [ODI]), psychological profiles (Pain Self-Efficacy Questionnaire, PSEQ; Pain Catastrophizing Scale, PCS), and physical activity (physical activity vital signs [PAVS]). Logistic regression and principal component analysis were used to identify the predictors of response phenotypes. Results: Early (≥50% pain relief within 7-14 days of PNS implant that is sustained through the entire 60-day period) and delayed (<50% pain relief in the first 14 days but eventually reaching ≥50% before the end of the 60 days) responder rates were 26% and 43%, respectively. Non-responders (<50% pain relief at the end of the 60-day treatment period) comprised 30.1% of the group. Predictors of early response included high physical activity (OR=4.22, p=0.0006, Area Under the Curve [AUC] =0.81), high pain self-efficacy (OR=1.12, p=0.0004, AUC=0.86), and low catastrophizing (OR=0.88, p=0.0003, AUC=0.86). A delayed response was associated with a longer chronic pain duration (OR=0.83, p=0.027) and high baseline ODI (OR=0.43, p=0.002; AUC=0.79). Nonresponse was linked to psychological distress (eigenvalue =3.23, 40.3% variance), opioid dependency, and morbid obesity (eigenvalue =1.63, 20.4% variance). Conclusion: This real-world study showed that baseline physical activity, psychological resilience, and pain behaviors predicted response to a 60-day PNS. Non-responders presented with psychological distress, morbid obesity, and opioid dependence. These findings may refine patient selection and help to set treatment expectations for 60-day PNS.