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.