Purpose: To cross-culturally adapt the Patient-Specific Functional Scale (PSFS) into Arabic language and to examine its measurement properties in patients with lower extremity musculoskeletal disorders.
Materials and methods: The original English version of the PSFS was cross-culturally adapted into modern standard Arabic language following Beaton's guidelines. Patients with lower extremity musculoskeletal disorders (N = 116) were recruited to examine the test-retest reliability, measurement error, floor and ceiling effects, and construct validity of the Arabic PSFS. Construct validity was tested by examining eight predefined correlational hypotheses.
Results: Participants in the current study indicated that the Arabic PSFS was clear and understandable. The Arabic PSFS had very good test-retest reliability (ICC = 0.86) with no floor or ceiling issues. The standard error of measurement and the minimal detectable change of the Arabic PSFS were 0.64 and 1.49 points respectively indicating acceptable measurement error. The majority of the predefined construct validity hypotheses (75%) were supported by the results justifying the construct validity of the Arabic PSFS.
Conclusions: The Arabic PSFS is a comprehensible and easy to use measure. The Arabic PSFS has very good test-retest reliability, acceptable measurement error, and evidence supporting its construct validity as measure of activity limitation in patients with lower extremity musculoskeletal disorders.Implications for rehabilitationRehabilitation specialist can confidently interpret patient's score in the Arabic PSFS to represent the extent of activity limitation.Patients with unchanged clinical status will have similar scores in the Arabic PSFS with repeated administrations of the scale over time.The Arabic PSFS can be used in daily clinical practice and in research studies to measure activity limitation in Arabic-speakers with lower extremity musculoskeletal disorders.The Arabic PSFS enables rehabilitation specialist to quantify activity limitation in a way that is relevant to the culture and life style of Arabic-speakers.
Keywords: Psychometrics; lower extremity; lower limb; reliability; validation.