The American College of Physicians conducted a study "to provide a rigorous and balanced summary of the best available evidence about the effectiveness and safety and costs of the most popular complimentary and alternative medical therapies used to treat low back pain". Click on the link below to read the conclusions of their study.
http://www.annals.org/content/138/11/898.abstract?sid=64bc37af-fa71-4d1d-b566-334aa98d16f9
