Article

Self-reports of function may systematically overestimate the ability
of patients to move around postarthroplasty. The purpose of this study
was to estimate the magnitude of systematic differences in Lower Extremity
Functional Scale (LEFS) and Western Ontario and McMaster Universities
Osteoarthritis Index physical function subscale (WOMAC-PF) scores before and
after primary total knee arthroplasty (TKA) or total hip arthroplasty (THA) by
referencing the values to Six-Minute Walk Test (6MWT) distances and Timed "Up &
Go" Test (TUG) times. DESIGN: This study was a secondary analysis of data from a
prospective cohort study. METHODS: The LEFS, WOMAC, 6MWT, and TUG were
administered to 85 patients prearthroplasty and once at 9 to 13 weeks
postarthroplasty. Regression analysis was applied using a robust error term for
clustered data. With the self-report measures as dependent variables and
performance measures, occasion (prearthroplasty or postarthroplasty), and
performance measure-by-occasion as independent variables, 3 propositions were
examined: (1) the relationship between self-report and performance measures is
identical prearthroplasty and postarthroplasty (ie, regression lines are
coincident); (2) the relationship differs between occasions, but is consistent
(ie, regression lines are parallel); (3) the relationship is not consistent (ie,
the regression lines are not parallel). RESULTS: For all analyses, the results
supported the second proposition (ie, the relationship differed between
occasions, but was consistent). The systematic differences varied by location of
arthroplasty, but were similar for both performance tests. For the LEFS, the
difference was approximately 11 points for patients who received TKA and 13
points for patients who received THA. For the WOMAC-PF, the difference was
approximately 12 points for patients who received TKA and 19 points for patients
who received THA. These differences exceed the minimal clinically important
change for an individual patient. LIMITATIONS: The findings are specific to 9 to
13 weeks postarthroplasty. CONCLUSION: Dependence on scores of self-report
measures alone, without knowledge of the magnitude of the identified systematic
differences, will result in overestimating the ability of patients to move around
postarthroplasty.

Langue : ANGLAIS