Spreading of pain and insomnia in patients with chronic pain: results from a national quality registry (SQRP)

To explore how demographics, pain, psychosocial factors and insomnia relate to the spread of chronic pain. The study included 708 patients (68% women; median age 46 years; interquartile range 35-57 years) with chronic pain who were referred to a multidisciplinary pain centre. Spreading of pain was assessed using a questionnaire covering 36 anatomically predefined pain regions. Data were collected on demographics, pain symptoms, psychological distress, and insomnia (Insomnia Severity Index). Four sub-categories of chronic pain were established: chronic local pain, chronic regional pain medium, chronic regional pain heavy, and chronic widespread pain. The median number of pain regions was 10 (interquartile range 6-18). Prevalence of chronic pain was as follows: chronic local pain 9%, chronic regional pain medium 21%, chronic regional pain heavy 39%, and chronic widespread pain 31%. In the regression models, being a woman and persistent pain duration had the strongest associations with spreading of pain, but anxiety, pain interference, and insomnia were also important factors. Spreading of chronic pain can only partly be explained by the simultaneous levels of insomnia. Female sex, pain duration, pain interference and anxiety appear to have more significant relationships with the spread of pain. Targeting these factors may lead to improvements in treatment and prevention strategies.