Table 2

Listing of potential confounders and effect modifiers, adjusted for in multiple regression analysis

Demographic and patient related characteristics
Gender, country, age, education, and Quetelet Index
Work related interventions and characteristics
Other ergonomic interventions (adaptation workplace, job tasks adaptation, working hours adaptation, therapeutic work resumption, job training, sheltered workshop)
Patient working hours, patient job duration, firm company size, patient work ability, attitude towards work, physical job demands, social support, job strain (Karasek Theorell’s demand-support-control scale)
Health related characteristics
General health (subscale of SF-36), active coping, passive coping, co-morbidity (interference with work resumption), pain intensity (von Korff pain intensity scale), pain sciatica, sickleave history due to back pain (in the last year), patient functional limitations (Hannover ADL)
Medical interventions
Surgery, pain medication, passive treatment, manipulation, active treatment (individual or groupwise training, gymnastics, back school)