To address the high prevalence of chronic low back pain in community-dwelling older adults, Weiner and colleagues performed a randomized controlled trial evaluating the efficacy of percutaneous electrical nerve stimulation (PENS) combined with physical therapy in patients older than 65 years. According to a well-designed study, acupuncture has not proved beneficial in the treatment of chronic low back pain. PENS is based on anatomic and physiologic principles, whose end point is stimulation of endogenous opioids to produce an analgesic effect.
Subjects were randomized to a treatment or control group after exclusion for neurologic disorders, known spinal pathology, prominent radicular pain, and other conditions. Pain intensity and pain-related disability, physical performance, psychosocial factors, cognitive function, and medications were assessed in addition to demographic data. Over six weeks, the treatment group received PENS treatment and physical therapy, while the control group received sham PENS treatment and physical therapy.
The treatment group achieved significant pain reduction (P <.001), which was maintained to the three-month follow-up, but the control group did not (P = .94). The treatment group also had significant reductions in pain-related disability (P = .002), while the control group did not (P = .81). Significant differences of secondary outcomes included reductions in chair-rise performance times in the treatment group and an increased number of dynamic lifts. There were no differences between groups in the functional reach task and static lifting strength. Both groups improved gait speed.
The authors found that PENS plus physical therapy produced sustained reductions in pain intensity and disability and improved chair-rise times and lifting endurance. The authors note that physical therapy alone (when given with sham PENS) had no therapeutic benefit, possibly because the success of physical therapy depends on a minimum threshold at which patients are able to cooperate.
The authors cite a number of limitations in this trial, including the difficulty of creating a convincing analog for the control group (the control group did not receive electrical stimulation, only placement of acupuncture needles). The importance of this trial is that it represents the first comprehensive attempt to apply a complementary intervention modality to older adults with chronic low back pain.