4.1. Study population

The study population consisted of consecutive, eligible sciatic patients with unilateral symptoms to below the knee that had lasted 3 to 28 weeks. Leg pain had to be at least comparable with that of back pain. A positive dural tension sign (limited straight leg raising) was not a prerequisite for entry. The exclusion criteria were an earlier back operation, an application for early retirement, clinical depression anticoagulation treatment, unstable diabetes, epidural injection during the preceding three months, pregnancy, allergy to any ingredients of the treatment agents, and rare causes of sciatica such as synovial cysts and non-degenerative spondylolisthesis. The patients had been referred by general practitioners in the catchment area of Oulu University Hospital (population 360 000). The study protocol was approved by the ethics committee of the Oulu University Hospital.

There were 160 sciatic patients in studies I, IV and V, 159 patients in the study II (blood sample not obtained from one patient), and 153 patients in the study III (6 patients with the Trp2 allele excluded).