Table 3 Selected prognostic variables for subgroup analysis.

Demographic variables:

   • Age < 40 years versus > 40 years

   • Non-physical versus physical demanding jobs

Anamnestic and neurological variables:

   • Influence of sitting on complaints versus no influenec

   • Quetelet index < 25 versus > 25

   • Straight leg raising < 30° without back pain versus with back pain

Radiological variables:

   • MRI disc sequester versus contained disc herniation

   • Median versus mediolateral and lateral disc herniation

   • High versus low height of disc level