Page 183 - The value of total hip and knee arthroplasties for patients

This study concluded that the constructs treatment expectancy, treatment credibility, hope,optimism and pessimism are distinguishable inTHA andTKA patients.Postdoc, we determined that all constructs, except hope, showed substantial specific variance unique from the general factor.
In Chapter 6, the predictive value of patients’ pre-operative general and specific outcome expectations on postoperative pain and function after total knee and total hip arthroplasties was studied.
It concerned the same cohort as described in Chapters 3-5, with this analysis including 148 THA and 146 TKA patients completing measurements preoperatively and 12 months after surgery. Primary outcomes for the present analysis were the KOOS and HOOS activities of daily living and pain subscale scores at 12 months After surgery. Patients’ preoperative outcome expectations were measured with the Credibility Expectancy Questionnaire (CEQ) and the Hospital for Special Surgery expectations surveys (HSS). Other candidate predictors of outcome were: preoperative pain and function, gender, age, education level, BMI, Kellgren and Lawrence score, mental health and treatment credibility.
Multivariate linear regression analyses were employed with postoperative pain (KOOS/HOOS pain) and function (KOOS/HOOS function) as dependent variables. Besides the CEQ and HSS, we selected the candidate predictors of outcome. A backwards elimination method was used for these analyses.This procedure started with including all candidate variables of outcome in the model, subsequently the least significant variable was removed (the one with the highest p-value).The model was thereafter refitted without this variable, and again the least significant variable was removed.This process was repeated until all predictor variables in the model had a p-value < 0.10.
Patients’ outcome expectations were consistently part of the combination of variables that best predicted outcomes for both TKA and THA. The amount of variance explained by the prediction models ranged between 17.0% and 30.3%, with higher scores on the expectation measures predicting better outcomes. However, the amount of variance explained by the expectation measures alone was limited. Therefore, it was suggested that with the consideration of total joint replacement, orthopaedic surgeons should take a range of variables into account,
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