title: Do abnormal serum lipid levels increase the risk of chronic low back pain? The Nord-Trøndelag Health Study.
abstract: BACKGROUND
  Cross-sectional studies suggest associations between abnormal lipid levels and prevalence of low back pain (LBP), but it is not known if there is any causal relationship.
  
  
  OBJECTIVE
  The objective was to determine, in a population-based prospective cohort study, whether there is any relation between levels of total cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides and the probability of experiencing subsequent chronic (LBP), both among individuals with and without LBP at baseline.
  
  
  METHODS
  Information was collected in the community-based HUNT 2 (1995-1997) and HUNT 3 (2006-2008) surveys of an entire Norwegian county. Participants were 10,151 women and 8731 men aged 30-69 years, not affected by chronic LBP at baseline, and 3902 women and 2666 men with LBP at baseline. Eleven years later the participants indicated whether they currently suffered from chronic LBP.
  
  
  RESULTS
  Among women without LBP at baseline, HDL cholesterol levels were inversely associated and triglyceride levels positively associated with the risk of chronic LBP at end of follow-up in analyses adjusted for age only. Adjustment for the baseline factors education, work status, physical activity, smoking, blood pressure and in particular BMI largely removed these associations (RR: 0.96, 95% CI: 0.85-1.07 per mmol/l of HDL cholesterol; RR: 1.16, 95% CI: 0.94-1.42 per unit of lg(triglycerides)). Total cholesterol levels showed no associations. In women with LBP at baseline and men without LBP at baseline weaker relationships were observed. In men with LBP at baseline, an inverse association with HDL cholesterol remained after complete adjustment (RR: 0.83, 95% CI: 0.72-0.95 per mmol/l).
  
  
  CONCLUSIONS
  Crude associations between lipid levels and risk of subsequent LBP in individuals without current LBP are mainly caused by confounding with body mass. However, an association with low HDL levels may still remain in men who are already affected and possibly experience a higher pain intensity.
authors.affiliation: Department of Neurology and FORMI, Oslo University Hospital, Oslo, Norway.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Heuch
authors.affiliation: Department of Mathematics, University of Bergen, Bergen, Norway.
authors.forename: Ivar
authors.initials: I
authors.lastname: Heuch
authors.affiliation: Department of Neuroscience, Norwegian University of Science and Technology, and Norwegian National Headache Centre, Department of Neurology, St. Olavs Hospital, Trondheim, Norway.
authors.forename: Knut
authors.initials: K
authors.lastname: Hagen
authors.affiliation: Department of Neurology and FORMI, Oslo University Hospital, Oslo, Norway; Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: John-Anker
authors.initials: JA
authors.lastname: Zwart
mesh_terms: D000328:Adult; D000368:Aged; D008076:Cholesterol, HDL / Q000097:blood*; D005260:Female; D006306:Health Surveys; D006801:Humans; D017116:Low Back Pain / Q000097:blood* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009664:Norway; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D014280:Triglycerides / Q000097:blood*
chemical_list: D008076:Cholesterol, HDL; D014280:Triglycerides