Study design: A prospective, randomized, single (investigator) blind, comparative efficacy trial was conducted.
Objective: To compare the efficacy of continuous low-level heat wrap therapy (40 C, 8 hours/day) with that of ibuprofen (1200 mg/day) and acetaminophen (4000 mg/day) in subjects with acute nonspecific low back pain.
Summary of background data: The efficacy of topical heat methods, as compared with oral analgesic treatment of low back pain, has not been established.
Methods: Subjects (n = 371) were randomly assigned to heat wrap (n = 113), acetaminophen (n = 113), or ibuprofen (n = 106) for efficacy evaluation, or to oral placebo (n = 20) or unheated back wrap (n = 19) for blinding. Outcome measures included pain relief, muscle stiffness, lateral trunk flexibility, and disability. Efficacy was measured over two treatment days and two follow-up days.
Results: Day 1 pain relief for the heat wrap (mean, 2) was higher than for ibuprofen (mean, 1.51; P = 0.0007) or acetaminophen (mean, 1.32; P = 0.0001). Extended mean pain relief (Days 3 to 4) for the heat wrap (mean, 2.61) also was higher than for ibuprofen (mean, 1.68; P = 0.0001) or acetaminophen (mean, 1.95; P = 0.0009). Lateral trunk flexibility was improved with the heat wrap (mean change, 4.28 cm) during treatment (P </= 0.009 vs acetaminophen [mean change, 2.93 cm], P </= 0.001 vs ibuprofen [mean change, 2.51 cm]). The results were similar on Day 4. Day 1 reduction in muscle stiffness with the heat wrap (mean, 16.3) was greater than with acetaminophen (mean, 10.5; P = 0.001). Disability was reduced with the heat wrap (mean, 4.9), as compared with ibuprofen (mean, 2.7; P = 0.01) and acetaminophen (mean, 2.9; P = 0.0007), on Day 4. None of the adverse events were serious. The highest rate (10.4%) was reported in the ibuprofen group.
Conclusion: Continuous low-level heat wrap therapy was superior to both acetaminophen and ibuprofen for treating low back pain.