Patient characteristics
| Variables | Variables (measurement) |
| Age | Years of age (calculated from registered date of birth) |
| Gender | % Female |
| Socioeconomic status | Highest education level, source of income (categorical rating items) |
| Coping style | Utrecht Coping List81 (validated questionnaire) |
| Environment | Presence of problems with regard to social life, financial situation, trauma, work situation (categorical rating items) |
| Symptoms | Duration (months; calculated from the date of onset), course (categorical rating item) and pain location (standard physical examination report) |
| Physical status | Body mass index, blood pressure, musculoskeletal conditions (standard physical examination report) |
| Other treatment | (Changes of) presence of medication usage, frequency of healthcare visits, previous visits to health providers (medical specialists, physiotherapists and/or psychologist) (categorical rating items) |
| Treatment (modules) received | Automatic logs of session presence (determined from absence registrations by healthcare providers) |