Table 1

Characteristics of the cohort

Demographic datan (%)
Age at baseline (mean (SD), y)  23.7 (7.4)
Sex:
 Women590 (85)
 Men104 (15)
History of low back pain:
 Cases at baseline277 (40)
  At baseline:
   Current LBP 86 (31)
   Low back pain ⩽12 months ago191 (67)
  Over follow up:
   None 10 (4)
   One episode 12 (4)
   Multiple episodes136 (49)
   Uncertain1-150 119 (43)
 Non-cases at baseline417 (60)
  At baseline:
   Low back pain >12 months ago 69 (17)
   Never had low back pain348 (84)
  Over follow up:
   None 59 (14)
   One episode 37 (9)
   Multiple episodes113 (27)
   Uncertain1-150 208 (50)
Work history:
 At baseline:
  No full time work369 (54)
  Full time work >3 months311 (45)
  Full time work >12 months265 (38)
 Over follow up:
  ⩾1 Part time job510 (74)
Psychological strain, history from the general health questionnaire:
 High at baseline198 (29)
  Over follow up:
   No high score  7 (4)
   One high score 12 (6)
   Multiple high scores 87 (44)
   Uncertain1-150  92 (47)
 Not high at baseline494 (71)
  Over follow up:
   No high score 87 (18)
   One high score 35 (7)
   Multiple high scores131 (27)
   Uncertain1-150 241 (49)
General health at baseline:
 BMI (mean (SD)) 23.5 (4.2)
 Currently smoke179 (26)
 Regular vigorous exercise485 (70)

  • ↵1-150 At least one missing follow up makes unambiguous classification impossible.