title: Predictors of persistent pain after total knee arthroplasty: a systematic review and meta-analysis.
abstract: BACKGROUND
  Several studies have identified clinical, psychosocial, patient characteristic, and perioperative variables that are associated with persistent postsurgical pain; however, the relative effect of these variables has yet to be quantified. The aim of the study was to provide a systematic review and meta-analysis of predictor variables associated with persistent pain after total knee arthroplasty (TKA).
  
  
  METHODS
  Included studies were required to measure predictor variables prior to or at the time of surgery, include a pain outcome measure at least 3 months post-TKA, and include a statistical analysis of the effect of the predictor variable(s) on the outcome measure. Counts were undertaken of the number of times each predictor was analysed and the number of times it was found to have a significant relationship with persistent pain. Separate meta-analyses were performed to determine the effect size of each predictor on persistent pain. Outcomes from studies implementing uni- and multivariable statistical models were analysed separately.
  
  
  RESULTS
  Thirty-two studies involving almost 30 000 patients were included in the review. Preoperative pain was the predictor that most commonly demonstrated a significant relationship with persistent pain across uni- and multivariable analyses. In the meta-analyses of data from univariate models, the largest effect sizes were found for: other pain sites, catastrophizing, and depression. For data from multivariate models, significant effects were evident for: catastrophizing, preoperative pain, mental health, and comorbidities.
  
  
  CONCLUSIONS
  Catastrophizing, mental health, preoperative knee pain, and pain at other sites are the strongest independent predictors of persistent pain after TKA.
authors.affiliation: Health and Rehabilitation Research Institute, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand gwyn.lewis@aut.ac.nz.
authors.forename: G N
authors.initials: GN
authors.lastname: Lewis
authors.affiliation: Health and Rehabilitation Research Institute, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand Waitemata Pain Services, Waitemata District Health Board, Auckland, New Zealand.
authors.forename: D A
authors.initials: DA
authors.lastname: Rice
authors.affiliation: Health and Rehabilitation Research Institute, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.
authors.forename: P J
authors.initials: PJ
authors.lastname: McNair
authors.affiliation: Waitemata Pain Services, Waitemata District Health Board, Auckland, New Zealand Department of Anaesthesiology and Perioperative Medicine, North Shore Hospital, Auckland, New Zealand.
authors.forename: M
authors.initials: M
authors.lastname: Kluger
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D015982:Bias; D005260:Female; D006801:Humans; D008297:Male; D010149:Postoperative Pain / Q000209:etiology*
keywords: arthroplasty; chronic pain; knee joint; meta-analysis