Medium-firm mattresses reduced pain-related disability more than firm mattresses in chronic, nonspecific low-back pain.

P a t i e n t s 313 adults who were ≥ 18 years of age (73% women), had ≥ 3 months of chronic lowback pain, and had pain while lying in bed or on rising. Exclusion criteria were referred pain; habitual prostration; possible systemic disease, inflammatory disease, or cancer; diagnosis or suspicion of fibromyalgia; pregnancy; habitually sleeping in a different bed ≥ 2 nights/wk; use of antiinflammatory medication with a 24-hour effect; or use of hypnotic analgesic, antiinflammatory, or relaxant medication from 1700 hours to the time at which pain on rising was assessed. 310 patients (99%) completed follow-up. I n t e r v e n t i o n 155 patients were allocated to medium-firm mattresses (European Committee for Standardization scale firmness rating 5.6 [1.0 = firmest and 10.0 = softest], and 158 patients were allocated to firm mattresses (firmness rating 2.3).