The number of total hip replacement (THR) surgeries performed in the US has increased dramatically in recent years. This increase is partly explained by the expanding age range for this surgery, including increasingly younger and older patients. Marked improvements of pain, physical function, social interaction and overall health are documented results in the literature for patients who undergo THR. However, little is known about patient-level predictors of outcomes, such as expectations, and standardized instruments for assessing patients' expectations need to be developed. Outcome expectations may affect decisions of patients to undergo elective hip replacement surgery. Expectations may be unrealistic and cause disappointment and low satisfaction for individuals. There is little work on how expectations affect satisfaction and health status. The purpose of this study is two fold: 1) to develop an instrument that measures expectation beliefs of persons who undergo elective primary THR and 2) to understand the associations between expectations, expectation confirmation and outcomes. A hip replacement expectation survey (HRES) was created from focus groups, personal interviews and expert opinion and will be developed in a larger sample of 200 subjects. We will concurrently evaluate criterion validity with the MOS 36-item short-form health survey (SF-36). A sub-sample of the same group of subjects will be evaluated at six months to assess the HRES's sensitivity to change. The results from the preoperative expectation analysis in phase l will be used to identify functional activities important to THR patients. These activities will be matched to variables in the Baltimore Hip Replacement Study database to evaluate a model of associations between expectations and outcomes after THR. For phase 1 of the project, psychometric properties of the expectations instrument will be evaluated with exploratory/confirmatory factor analyses, reliability analysis and correlations. In phase 2 of the project, univariate, bivariate and multivariate analysis techniques will be used to evaluate the influence of pre-operative expectations and the congruence between pre and post.operative expectations on mental and physical health and satisfaction. Strengths of associations between variables and the model fit of the data will be evaluated with generalized linear modeling.
