Effect of firmness of mattress on chronic non-specific low-back pain: randomised, double-blind, controlled, multicentre trial.

BACKGROUND A firm mattress is commonly believed to be beneficial for low-back pain, although evidence supporting this recommendation is lacking. We assessed the effect of different firmnesses of mattresses on the clinical course of patients with chronic non-specific low-back pain. METHODS In a randomised, double-blind, controlled, multicentre trial, we assessed 313 adults who had chronic non-specific low-back pain, but no referred pain, who complained of backache while lying in bed and on rising. Mattress firmness is rated on a scale developed by the European Committee for Standardisation. The H(s) scale starts at 1.0 (firmest) and stops at 10.0 (softest). We randomly assigned participants firm mattresses (H(s)=2.3) or medium-firm mattresses (H(s)=5.6). We did clinical assessments at baseline and at 90 days. Primary endpoints were improvements in pain while lying in bed, pain on rising, and disability. FINDINGS At 90 days, patients with medium-firm mattresses had better outcomes for pain in bed (odds ratio 2.36 [95% CI 1.13-4.93]), pain on rising (1.93 [0.97-3.86]), and disability (2.10 [1.24-3.56]) than did patients with firm mattresses. Throughout the study period, patients with medium-firm mattresses also had less daytime low-back pain (p=0.059), pain while lying in bed (p=0.064), and pain on rising (p=0.008) than did patients with firm mattresses. INTERPRETATION A mattress of medium firmness improves pain and disability among patients with chronic non-specific low-back pain.