Page 77 - The value of total hip and knee arthroplasties for patients
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                                Distinctiveness of Psychological Constructs
expectancies pre-operatively. For the present analysis pre-operative data of this subgroup were used. The larger study, as well as the extension for the subgroup was approved by the Medical Ethical Committee of the Rijnland General Hospital, Leiderdorp, the Netherlands (registration number 10/07). All participants gave written informed consent.
Measurement
One day prior to surgery all participants completed a questionnaire including sociodemographic, disease characteristics, Quality of Life and the Life Orientation
Test-Revised (LOT-R), the Hope Scale (HS) and the Credibility Expectancy Questionnaire (CEQ). Demographic characteristics included: age (years), sex
and education level. Disease characteristics pain and functioning were measured 5 using the Pain and ADL subscales of the HOOS (for THA patients) 12 and KOOS
(for TKA patients) 11 questionnaires. Quality of Life was measured using the SF- 36 questionnaire 45 from which mental component scores (MCS) and physical component scores (PCS) were derived.
Optimism (and Pessimism)
The Life OrientationTest- Revised33 is a 10 item self-reported questionnaire that aims to measure optimism.The questionnaire consists of 3 positively formulated items (e.g. I’m always optimistic about my future), 3 negatively formulated items (e.g. I rarely count on good things happening to me) and 4 filler items (e.g. It’s easy for me to relax), all items are answered on a 5 point Likert-type scale.The LOT-R was originally developed by Scheier and Carver in 199433 who called the LOT-R a unidimensional questionnaire in which the observed variables represent one latent factor called trait optimism. However others have argued that the items in the LOT-R represent two latent factors namely optimism and pessimism 18;20. Hence, sumscores range from 3-15 when two subscale scores are calculated or from 3-30 when one total score is calculated.The factor structure of the Dutch version of the LOT-R was tested recently.43 Results showed that the two factor model had the best fit.
Hope
The Hope Scale consists of 12 items of which 4 items measure ‘pathways’ (e.g.There are lots of ways around the problem), 4 items measure ‘agency’ (e.g. I meet the goals that I have set for myself) and 4 are filler items (e.g. I worry about my health).40 All
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