Lidocaine 5% Patch: An Open-Label Naturalistic Chronic Pain Treatment Trial and Prediction of Response

ABSTRACT Objective. There have been a few open‐label nonplacebo reports on the successful use of lidocaine 5% patch (L5P) for other types of pain besides postherpetic neuralgia, such as chronic low back pain. With the these reports, we began to utilize L5P routinely for chronic pain patients (CPPs) with various pain diagnoses. The purpose of this report was to describe the results of a retrospective review of this open‐label naturalistic L5P chronic pain treatment trial and to attempt to delineate predictors of perceived clinical response. Design. Consecutive CPPs were selected for this clinical trial according to the following inclusion criteria: the CPPs with pain greater than 6‐month duration and either a hyperalgesic pain area or trigger point, which could be covered by one L5P, were offered a 3‐day L5P naturalistic treatment trial. The purpose of this trial was to determine which CPPs would perceive improvement and continue using L5P. CPPs entering the trial completed the neuropathic pain scale (NPS) at entrance and completion of the trial. The senior author also completed a baseline information tool on each CPP entering this naturalistic trial. At the completion of the 3‐day trial, the CPPs were asked if they perceived pain improvement with the use of L5P. In the retrospective review, the CPPs were thus segregated into two groups, those with and without perceived clinical improvement, and were statistically compared for available clinical variables. Logistic regression was then utilized to determine which significant independent variables contributed to the correct prediction of perceived improvement. Setting. Multidisciplinary pain facility. Patients. Patients with chronic pain. Results. Of 362 consecutive CPPs, 114 or 31.5% were deemed candidates for this naturalistic trial. None of the CPPs refused or fulfilled exclusion criteria eliminating them from the trial. The total sample (N = 114) showed statistical improvement on all 10 NPS scales (except scales 4 and 6) plus the NPS 4, NPS nonallodynic 8, and NPS 10. The perceived clinically improved group (N = 87, 76.3% of those entering the trial), also showed perceived improvement on all preceding scales except 4 and 6. The perceived clinically nonimproved group (N = 27, 23.7% of those entering the trial) showed statistical improvement on scales B and NPS 10. Perceived improvement was predicted by the following variables: pain wakes patient up, patch placement not low back, and not in litigation.