E-STIM Trial: Comparing the Efficacy of the Empi Select TENS to a Control for the Treatment of Chronic Lower Back Pain

Inclusion Criteria: * Subjects must be 18-65 years of age. * Subjects must have reported low back pain of at least 3 months duration. * Subjects must report a low back pain score of 4 or greater on the 0-10 point Numerical Rating Scale (NRS) for average daily pain. * Subjects must have been on a stabilized analgesic medication regimen for 3 months or greater. * Subjects must be willing to discontinue use of all rescue pain medications for the duration of the trial (all PRN medications for breakthrough pain), except for OTC oral acetaminophen (up to 4 grams per day). * Subjects must be willing to refrain from starting any new lower back pain treatments for the duration of the trial. * Subjects must be willing and able to comply with all follow-up procedures (including completion of the daily diary) and return for scheduled follow- up visits. * Female subjects must be post-menopausal for at least 1 year, surgically sterile or willing to take a pregnancy test which must be negative prior to study enrollment. * Subjects must be willing and able to provide written informed consent and HIPAA authorization prior to enrollment into the study. Exclusion Criteria: * Subjects that have a demand type pacemaker or defibrillator. * Subjects that have had previous experience with electrotherapy. * Subjects that have had any failed back surgeries. * Subjects that have spinal stenosis which contributes to, or is the cause of lower back pain. * Subjects that have sciatica (lower back pain with radicular symptoms). * Subjects that have cauda equina syndrome. * Subjects that have fibromyalgia. * Subjects that have pain secondary to cancer. * Subjects who have cancer in the same anatomical location as their back pain. * Subjects that have any sensory deprivation or diagnosis of shingles or post- herpetic neuralgia (specifically in the mid-trunk region). * Subjects that have planned surgeries during the study period. * Subjects that have a history of alcohol or substance abuse in the last 5 years. * Subjects on psychoactive medication(s) that: 1. have had a change in dose or a change in medication type during the 3 months prior to screening, or 2. are expected to require a change in dose, or a new medication during the study. * Subjects that are seeking worker's compensation or any other legal claims. * Subjects that are pregnant or plan to become pregnant during the study period.