Table 1.

Demographic and Disease Characteristics Cases with Chronic Low Back Pain Given as Numbers N, Unless Stated Otherwise

Total number of cases	146 patients with lumbar disc degeneration
Ethnicity	Norwegian
Gender (Males/Females)	68/78
Age (8 year follow up), years	Range: 30-76, Mean [SD]: 53.2 [8.8]
Age of Onset, years	Range: 10-61, Mean [SD]: 32.9 [10.3]
Duration of pain (baseline), months	Range: 10-480, Mean [SD]: 128.8 [103.04]
Smokers/non-smokers/unknown	68/69/9
Surgical status (None/discectomy/lumbar fusion)	27/46/73
History of back pain in first degree relatives, with no treatment/conservative treatment/surgery/unknown	19/82/40/5