Overnight use of continuous low-level heatwrap therapy for relief of low back pain

Objective: To evaluate of the efficacy and safety of 8 hours of continuous, low-level heatwrap therapy administered during sleep. Design: Prospective, randomized, parallel, single-blind (investigator), placebo-controlled, multicenter clinical trial. Setting: Two community-based research facilities. Participants: Seventy-six patients, aged 18 to 55 years, with acute, nonspecific low back pain. Intervention: Subjects were stratified by baseline pain intensity and gender and randomized to one of the following treatments: evaluation of efficacy (heatwrap, n=33; coral placebo, n=34) or blinding (unheated wrap, n=5; oral ibuprofen, n=4). All treatments were administered for 3 consecutive nights with 2 days of follow-up. Main Outcome Measures: Primary: morning pain relief (hour 0) on days 2 through 4 (0-5-point verbal response scale). Secondary: mean daytime pain relief score (days 2-4, hours 0-8), mean extended pain relief score (day 4, hour 0; day 5, hour 0). muscle stiffness, lateral trunk flexibility, and disability (Roland-Morris Disability Questionnaire). Results: Heatwrap therapy was significantly better than placebo at hour 0 on days 2 through 4 for mean pain relief (P=.00005); at hours 0 through 8 on days 2 through 4 for pain relief (P<.001); at hour 0 on day 4, and at hour 0 on day 5 for mean pain relief (P<.001); on day 4 in reduction of morning muscle stiffness (P<.001); for increased lateral trunk flexibility on day 4 (P<.002); and for decreased low back disability on day 4 (P=.005). Adverse events were mild and infrequent. Conclusion: Overnight use of heatwrap therapy provided effective pain relief throughout the next day, reduced muscle stiffness and disability, and improved trunk flexibility. Positive effects were sustained more than 48 hours after treatments were completed.