Background: Low back pain is a common and costly health care problem. This pilot study evaluated the sensitivity of the 2-stopwatch and Paris plinth methodologies for assessing time-to-onset of pain relief and flexibility, respectively, with continuous, low-level heatwrap therapy.
Research design and methods: Subjects aged 18 to 55 years with at least moderate baseline acute low back pain were randomly assigned to either heatwrap or oral placebo for 8 hours. Unheated wrap (sham) and oral ibuprofen were included for blinding purposes only.
Results: Sixty-one subjects were randomly assigned to either heatwrap (n = 26), oral placebo (n = 25), sham wrap (n = 5), or oral ibuprofen (n = 5). Median time to confirmed first perceptible pain relief and to meaningful pain relief were significantly shorter for the heatwrap group compared with those assigned to oral placebo (96.5 vs > 240.0 min and 215.7 vs > 240.0 min, respectively; P < 0.05 for both). Among subjects receiving the heatwrap, 53.8% reported first perceptible and meaningful relief, compared with 28.0% receiving oral placebo. Subjective measures of pain relief, back stiffness, and global evaluation were more sensitive in detecting treatment differences than the plinth assessments of flexibility, range of motion, and pain. Three adverse events were reported as mild in severity and considered unrelated to study treatment.
Conclusions: The 2-stopwatch methodology is a viable approach for assessing onset of analgesia in low back pain; however, the plinth may not be a reliable method for assessing flexibility. Consistent with published studies involving much larger sample sizes, the heatwrap provided significantly faster and sustained pain relief than oral placebo in subjects with acute low back pain. Clinical Trial Identifier: NCT01045993.