title: Symptoms of Depression and Risk of Low Back Pain: A Prospective Co-Twin Study.
abstract: OBJECTIVE
  To investigate whether symptoms of depression increase the risk of low back pain (LBP), after adjusting for genetic and environmental influences.
  
  
  METHODS
  Baseline data of 1607 twins from the Murcia Twin Registry (Spain) were collected in 2009 to 2011 and follow-up data in 2013. Twins answered questions on depression-related symptomatology and LBP. Only participants not reporting chronic LBP (pain >6 mo) at baseline were included. The association between symptoms of depression and LBP was investigated using logistic regression analysis including the complete sample. Subsequent matched within-pair case-control analyses were performed with all complete dizygotic twin pairs discordant for LBP, followed by monozygotic twins.
  
  
  RESULTS
  In the total sample analysis, symptoms of depression did not significantly increase the risk of chronic LBP (odds ratio [OR]=1.40; 95% confidence interval [CI], 0.96-2.03), LBP care seeking (OR=1.21; 95% CI, 0.81-1.81), or activity-limiting LBP (OR=1.09; 95% CI, 0.69-1.72). State depression (participants' symptoms at the moment of the interview) was significantly associated with future care seeking (OR=1.06; 95% CI, 1.01-1.12) and activity-limiting LBP (OR=1.07; 95% CI, 1.01-1.14). A significant association was found between trait depression and activity-limiting LBP (OR=1.05; 95% CI, 1.01-1.10), but not for the other LBP outcomes. No significant association was observed in any of the subsequent case-control analyses.
  
  
  CONCLUSIONS
  The magnitude of the association between depression and LBP seems to be small and may be confounded by genetic and early shared environment influences, although firm conclusions could not be made due to small sample size in the case-control analysis. In addition, the observed association is dependent on the method of assessment used for both conditions.
authors.affiliation: *Arthritis & Musculoskeletal Research Group, Faculty of Health Sciences, The University of Sydney †Musculoskeletal Division, The George Institute for Global Health, The University of Sydney ‡Institute of Bone and Joint Research, The Kolling Institute, Sydney Medical School, The University of Sydney, Sydney, NSW ∥Psychiatric Genetics Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Qld, Australia ¶Centre for Epidemiology & Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Vic., Australia §Murcia Twin Registry, Department of Human Anatomy and Psychobiology, University of Murcia and IMIB-Arrixaca, Murcia, Spain.
authors.forename: Marina B
authors.initials: MB
authors.lastname: Pinheiro
authors.forename: Manuela L
authors.initials: ML
authors.lastname: Ferreira
authors.forename: Kathryn
authors.initials: K
authors.lastname: Refshauge
authors.forename: Lucia
authors.initials: L
authors.lastname: Colodro-Conde
authors.forename: Francisca
authors.initials: F
authors.lastname: González-Javier
authors.forename: John L
authors.initials: JL
authors.lastname: Hopper
authors.forename: Juan R
authors.initials: JR
authors.lastname: Ordoñana
authors.forename: Paulo H
authors.initials: PH
authors.lastname: Ferreira
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002908:Chronic Disease / Q000453:epidemiology / Q000523:psychology; D003863:Depression / Q000453:epidemiology* / Q000235:genetics; D005260:Female; D005500:Follow-Up Studies; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease; D006801:Humans; D008137:Longitudinal Studies; D017116:Low Back Pain / Q000453:epidemiology* / Q000235:genetics / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D010342:Patient Acceptance of Health Care; D011446:Prospective Studies; D012042:Registries; D012307:Risk Factors; D013030:Spain; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic