title: Physical and mental function and incident low back pain in seniors: a population-based two-year prospective study of 1387 Danish Twins aged 70 to 100 years.
abstract: METHODS
  Prospective cohort study.
  
  
  OBJECTIVE
  To investigate whether physical performance, grip strength, cognitive function, and depression symptomatology are risk factors for incident low back pain (LBP) over a 2-year period in seniors.
  
  
  BACKGROUND
  LBP is common in the older age groups, but little is known about predictors of LBP in this age group.
  
  
  METHODS
  Data from the 2001 and 2003 data collection from the population-based Longitudinal Study of Aging Danish Twins formed the basis of this analysis. Participants free from LBP at baseline (no LBP during the past month, N = 1387) were included and interview data on overall physical function, and assessment of grip strength, overall cognitive function, and depression at baseline were obtained. LBP status at follow-up was assessed using a modified version of the Standardized Nordic Questionnaire. Logistic regression was used to assess the associations between the baseline risk factors and LBP at follow-up.
  
  
  RESULTS
  A total of 1387 persons 70 to 100 years of age at baseline were included in the analyses. Of the initially LBP-free individuals, 7% had experienced LBP more than 30 days out of the past year, 7% had altered or decreased their physical activities due to LBP, and 11% had received treatment for LBP at follow-up. Good overall physical function (being among the top 50%) at baseline was protective for LBP of more than 30 days duration and for diminishing physical activities due to LBP and for care seeking due to LBP. High depression scores (being among the top 25%) were strongly associated with altering or decreasing daily activities because of LBP. Grip strength and overall cognitive performance at baseline were associated with lower incidence of LBP and decreasing activities due to LBP at follow-up; however, these associations were not statistically significant.
  
  
  CONCLUSIONS
  Poor overall physical function and depression symptomatology are associated with LBP and consequences of LBP in persons 70 years of age and older.
authors.affiliation: Nordic Institute of Chiropractic and Clinical Biomechanics, Clinical Locomotion Science, Odense, Denmark. j.hartvigsen@nikkb.dk
authors.forename: Jan
authors.initials: J
authors.lastname: Hartvigsen
authors.forename: Henrik
authors.initials: H
authors.lastname: Frederiksen
authors.forename: Kaare
authors.initials: K
authors.lastname: Christensen
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D003071:Cognition; D015331:Cohort Studies; D003863:Depression / Q000209:etiology* / Q000523:psychology; D004200:Diseases in Twins / Q000503:physiopathology / Q000523:psychology / Q000628:therapy; D005260:Female; D018737:Hand Strength; D006801:Humans; D016015:Logistic Models; D017116:Low Back Pain / Q000503:physiopathology* / Q000523:psychology* / Q000628:therapy; D008297:Male; D009043:Motor Activity; D010342:Patient Acceptance of Health Care; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires