title: Can Optimism, Pessimism, Hope, Treatment Credibility and Treatment Expectancy Be Distinguished in Patients Undergoing Total Hip and Total Knee Arthroplasty?
abstract: OBJECTIVE
  The constructs optimism, pessimism, hope, treatment credibility and treatment expectancy are associated with outcomes of medical treatment. While these constructs are grounded in different theoretical models, they nonetheless show some conceptual overlap. The purpose of this study was to examine whether currently available measurement instruments for these constructs capture the conceptual differences between these constructs within a treatment setting.
  
  
  METHODS
  Patients undergoing Total Hip and Total Knee Arthroplasty (THA and TKA) (Total N = 361; 182 THA; 179 TKA), completed the Life Orientation Test-Revised for optimism and pessimism, the Hope Scale, the Credibility Expectancy Questionnaire for treatment credibility and treatment expectancy. Confirmatory factor analysis was used to examine whether the instruments measure distinct constructs. Four theory-driven models with one, two, four and five latent factors were evaluated using multiple fit indices and Δχ2 tests, followed by some posthoc models.
  
  
  RESULTS
  The results of the theory driven confirmatory factor analysis showed that a five factor model in which all constructs loaded on separate factors yielded the most optimal and satisfactory fit. Posthoc, a bifactor model in which (besides the 5 separate factors) a general factor is hypothesized accounting for the commonality of the items showed a significantly better fit than the five factor model. All specific factors, except for the hope factor, showed to explain a substantial amount of variance beyond the general factor.
  
  
  CONCLUSIONS
  Based on our primary analyses we conclude that optimism, pessimism, hope, treatment credibility and treatment expectancy are distinguishable in THA and TKA patients. Postdoc, we determined that all constructs, except hope, showed substantial specific variance, while also sharing some general variance.
authors.affiliation: Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Tsjitske M
authors.initials: TM
authors.lastname: Haanstra
authors.affiliation: Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Claire
authors.initials: C
authors.lastname: Tilbury
authors.affiliation: Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research, VU University Medical Centre, Amsterdam, The Netherlands; Musculoskeletal Division, The George Institute for Global Health, The University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Kamper
authors.affiliation: Department of Orthopaedics, Rijnland Ziekenhuis, Leiderdorp, The Netherlands.
authors.forename: Rutger L
authors.initials: RL
authors.lastname: Tordoir
authors.affiliation: Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Thea P M
authors.initials: TP
authors.lastname: Vliet Vlieland
authors.affiliation: Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Rob G H H
authors.initials: RG
authors.lastname: Nelissen
authors.affiliation: Department of Clinical Psychology and the EMGO Institute for Health and Care Research, VU University Amsterdam, The Netherlands.
authors.forename: Pim
authors.initials: P
authors.lastname: Cuijpers
authors.affiliation: Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Henrica C W
authors.initials: HC
authors.lastname: de Vet
authors.affiliation: Department of Rehabilitation Medicine and the EMGO Institute, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
authors.affiliation: Department of Epidemiology and Biostatistics, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Dirk L
authors.initials: DL
authors.lastname: Knol
authors.affiliation: Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research, VU University Medical Centre, Amsterdam, The Netherlands; Department of Health Sciences and the EMGO Institute for Health and Care Research, VU University, Amsterdam, The Netherlands.
authors.forename: Raymond W
authors.initials: RW
authors.lastname: Ostelo
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000706:statistics & numerical data*; D019645:Arthroplasty, Replacement, Knee / Q000706:statistics & numerical data*; D005260:Female; D065026:Hope; D006801:Humans; D008297:Male; D008875:Middle Aged; D000067656:Optimism; D017063:Outcome Assessment, Health Care; D000067657:Pessimism; D012307:Risk Factors; D011795:Surveys and Questionnaires