SPINE 2008 – Volume 33, Number 7 Kim Bergholdt, Rasmus N. Fabricius, Tom Bendix, Abstract Study Design: A randomized/stratified, single-blinded, parallel-group study. Objective: To evaluate 3 structurally different mattresses relative influence on patients with chronic low back pain (CLBP). Summary of Background Data: In several advertisements, it is proclaimed that certain mattresses have a positive effect on LBP, and especially a hard mattress is commonly believed to have a positive effect. Methods: One hundred sixty CLBP patients were randomized to 1 of 3 groups, having a mattress/bed mounted in their sleeping room for 1 month. The beds were: (1) waterbed (Akva), (2) body-conforming foam mattress (Tempur), and (3) a hard mattress (Innovation Futon). At baseline and after 4 weeks, a blinded observer interviewed the patients on LBP levels (0-10), daily function (activities of daily living, 0-30), and on the amount of sleeping hours/night. Results: Because of dropout of 19 patients before baseline, the analyses were performed on 141 patients. During the 1-month trial period another 27 patients stopped ahead of time, which were accounted for by worse case as well as no-change analyses. Both the waterbed and the foam mattress seemed superior to the hard mattress, especially when using the probably most relevant worst case data. There were no relevant difference between the effects of the water bed and the foam bed. Conclusion: The Waterbed and foam mattress’ did influence back symptoms, function and sleep more positively as apposed to the hard mattress, but the differences were small.