The effect of low back pain and neck-shoulder stiffness on health-related quality of life: a cross-sectional population-based study.

Comorbidity of the two diseases is prevalent in 23% of the men and 33% of women in the Japanese sample. Although NSS, LBP, and comorbidity were independently associated with QOL in terms of pain, QOL was worse in individuals who exhibited comorbidity than in those without symptoms or with NSS alone.