Peripheral Nerve Field Stimulation for Chronic Back Pain: Therapy Outcome Predictive Factors.

OBJECTIVE: To identify variables that influence pain reduction following peripheral nerve field stimulation (PNFS) in order to identify a potential responder profile. METHODS: Exploratory univariate and multivariate (random forest) analyses were performed separately on 2 randomized controlled trials and a registry; all included patients with chronic back pain, mainly failed back surgery syndrome. An international expert panel judged the clinical relevance of variables to identify responders by consensus. RESULTS: Variables identified that may help predict PNFS success in patients with back pain include patient and pain characteristics (age, time since onset of pain and spinal surgery, pain medication history, position and size of pain area, pain severity, mixed nociceptive/neuropathic pain, health-related quality of life, depression, functional disability, and leg pain status), implant procedure variables (the number and position of leads, paresthesia coverage, and amount of pain relief during the trial), and programming (number of programs, cathodes, and anodes; pulse rate; pulse width; and percentage of device usage). CONCLUSIONS: While these analyses are exploratory and restricted to a limited sample size, they suggest variables that may play a role in predicting a therapeutic response. These results, however, are informative only and should be cautiously interpreted. Future research to validate the variables in a clinical study is needed.