Potential confounder | Description |
---|---|
Sex | Male, female |
Age | Continuous |
Body mass index | <18.5, 18.5-24.9, 25-30, >30 continuous |
Daily smoking | Yes, no |
Level of education | Elementary (1-9 y), secondary (10-12 y), university (13-16 y), higher academic education (>16 y) |
Pain intensity at baseline | Mean score on the Chronic Pain Questionnaire based on current pain intensity, worst pain intensity during the last 4 weeks and average pain intensity during the last 4 weeks, continuous |
Pain-related disability at baseline | Mean score on the Chronic Pain Questionnaire based on how pain hindered daily, recreational-, social-, and family activities as well as interfered with work during the last 4 weeks, continuous |
Pain duration at baseline | <1 month, 1-3 months, 4-6 months, >6 months |
Previous episodes of pain | Yes, no |
Pain location | Neck pain, back pain or equally bad pain in both locations |