title: Does Familial Aggregation of Chronic Low Back Pain Affect Recovery?: A Population-Based Twin Study.
abstract: METHODS
  Longitudinal twin-cohort study.
  
  
  OBJECTIVE
  To investigate the effect familial aggregation of chronic low back pain (LBP) has on the recovery from chronic LBP.
  
  
  BACKGROUND
  LBP is a worldwide problem, with pain and disability often becoming chronic. Genetics and familial behaviors could significantly affect the recovery from chronic LBP but have not been extensively investigated.
  
  
  METHODS
  A total of 624 Spanish twins from the Murcia Twin Registry reported experiencing chronic LBP within the past 2 years during the 2009/11 data collection wave and were followed up in 2013. Familial aggregation of chronic LBP was determined by the co-twin experiencing chronic LBP within the past 2 years at baseline. Twins reporting LBP "within the past 4 weeks" at follow-up were considered to have not recovered.
  
  
  RESULTS
  There were 455 twins with available data on LBP at follow-up and available data on LBP from their co-twin at baseline. Twins with an affected co-twin at baseline were significantly more likely to have not recovered from chronic LBP at follow-up (odds ratio [OR] = 1.6, 95% confidence interval [CI]: 1.0-2.4, P = 0.046). This relationship was stronger for monozygotic twins (OR = 2.5, 95% CI: 1.3-4.8, P = 0.006) (n = 172) but disappeared when considering only dizygotic twins (OR = 1.1, 95% CI: 0.6-2.0, P = 0.668) (n = 283). Sibling-relative recurrence risk (λ s) was 1.2 for the total sample, 1.5 for monozygotic twins, and 1.1 for dizygotic twins.
  
  
  CONCLUSIONS
  Having a sibling with chronic LBP at baseline increased the likelihood of LBP at follow-up by 20%, with this likelihood increasing to 50% if the sibling was an identical twin. These results are novel and highlight the important influence genetics have on people's recovery from chronic LBP. Information regarding the presence of chronic LBP within a family is easy to obtain and has the potential to inform clinicians on which patients are less likely to recover when treatment implementation is not considered.
  
  
  METHODS
  3.
authors.affiliation: Discipline of Physiotherapy, Faculty of Health Sciences, University of Sydney, Sydney, Australia.
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Zadro
authors.affiliation: Discipline of Physiotherapy, Faculty of Health Sciences, University of Sydney, Sydney, Australia.
authors.forename: Debra
authors.initials: D
authors.lastname: Shirley
authors.affiliation: Murcia Twin Registry, Department of Human Anatomy and Psychobiology, University of Murcia, Murcia, Spain.|Murcia Institute for Biomedical Research (IMIB-Arrixaca), Murcia, Spain.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Sánchez-Romera
authors.affiliation: Murcia Twin Registry, Department of Human Anatomy and Psychobiology, University of Murcia, Murcia, Spain.|Murcia Institute for Biomedical Research (IMIB-Arrixaca), Murcia, Spain.
authors.forename: Juan R
authors.initials: JR
authors.lastname: Ordoñana
authors.affiliation: Discipline of Physiotherapy, Faculty of Health Sciences, University of Sydney, Sydney, Australia.
authors.forename: Paulo H
authors.initials: PH
authors.lastname: Ferreira
mesh_terms: D059350:Chronic Pain / Q000453:epidemiology / Q000235:genetics / Q000534:rehabilitation / Q000628:therapy; D006801:Humans; D008137:Longitudinal Studies; D017116:Low Back Pain / Q000453:epidemiology / Q000235:genetics / Q000534:rehabilitation / Q000628:therapy; D013030:Spain; D014429:Twins, Dizygotic / Q000235:genetics / Q000706:statistics & numerical data; D014430:Twins, Monozygotic / Q000235:genetics / Q000706:statistics & numerical data