Article

Comparative effectiveness research across cultures requires unbiased
measures that accurately detect clinical differences between patient groups.
The purpose of this study was to assess the presence and impact of
differential item functioning (DIF) in knee functional status (FS) items
administered using computerized adaptive testing (CAT) as a possible cause for
observed differences in outcomes between 2 cultural patient groups in a polyglot
society. This study was a secondary analysis of prospectively collected
data. We evaluated data from 9,134 patients with knee impairments from
outpatient physical therapy clinics in Israel. Items were analyzed for DIF
related to sex, age, symptom acuity, surgical history, exercise history, and
language used to complete the functional survey (Hebrew versus Russian). RESULTS:
Several items exhibited DIF, but unadjusted FS estimates and FS estimates that
accounted for DIF were essentially equal (intraclass correlation coefficient
[2,1]>.999). No individual patient had a difference between unadjusted and
adjusted FS estimates as large as the median standard error of the unadjusted
estimates. Differences between groups defined by any of the covariates considered
were essentially unchanged when using adjusted instead of unadjusted FS
estimates. The greatest group-level impact was <0.3% of 1 standard deviation of
the unadjusted FS estimates. LIMITATIONS: Complete data where patients answered
all items in the scale would have been preferred for DIF analysis, but only CAT
data were available. CONCLUSIONS: Differences in FS outcomes between groups of
patients with knee impairments who answered the knee CAT in Hebrew or Russian in
Israel most likely reflected true differences that may reflect societal
disparities in this health outcome.

Langue : ANGLAIS