Page 102 - The value of total hip and knee arthroplasties for patients

Chapter 6
primary TKA or THA were invited by their surgeon to participate in the study. Exclusion criteria were: revision surgery, hemi-arthroplasty, tumor or rheumatoid arthritis, a functioning limiting comorbidity (for example (hemi)paresis), being not sufficiently competent in Dutch to complete a written survey, not being able to manage themselves or not having home care after surgery. Informed consent was obtained from the participants at the time of recruitment.
Assessments
One day prior to surgery all participants completed a survey including a number of sociodemographic, disease characteristics, patient expectations questionnaires and a number of patient reported outcome measures (PROMs). Approximately 12 months after surgery a survey assessing the same PROMs as pre-operatively was sent to the patients’ home address together with a pre-stamped return envelope. If the patient did not return the survey within 3 weeks, we attempted to contact the patient by phone and if necessary we sent another copy of the survey to the patient.
General outcome expectations and treatment credibility
Expectations about general recovery after surgery were assessed with the expectancy subscale of the Credibility Expectancy Questionnaire (CEQ) which contains three items that are scored on a 0-9 scale and hence the sum score ranges from 0-27[33;34]. An example of an item is “How much do you really feel that the surgery will help you to reduce your symptoms”. Next to outcome expectations the CEQ also contains a credibility subscale. Credibility is defined as “how believable, convincing and logical the treatment is” this concept is closely related to outcome expectations.The credibility subscale also contains three items that are scored on a 0-9 scale.
Specific outcome expectations
Outcome expectations for 17 (TKA) or 18 (THA) specific outcomes with regard to function and pain of hip or knee (eg walking stairs, pain during daytime) were measured with the Hospital for Special Surgery Knee and Hip Replacement and Knee Replacement Expectations Surveys[35;36] , from here on referred to as the HSS expectation surveys (separate questionnaires for TKA and THA). Answering options for all items are scored on a 0-4 scale (4= back to normal, 3=much improvement, 2=somewhat improvement, 1=small improvement, 0= don’t have this expectation). Principal component analysis with an oblique rotation was used to derive a coherent expectations for post-operative ‘function’ variable from the
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