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The Arabic version of the Lower Extremity Functional Scale is a reliable and valid measure of activity limitation in people with chronic obstructive pulmonary disease

Abstract Purpose To examine the psychometric properties of the Arabic version of the Lower Extremity Functional Scale (LEFS-Ar) in people with chronic obstructive pulmonary disease (COPD). Materials and methods Stable individuals with COPD (N = 70) confirmed by spirometry were asked to complete the LEFS-Ar, St George’s Respiratory Questionnaire (SGRQ) and performed the Six-Minute Walk Test (6MWT). Participants were also asked to complete LEFS-Ar for the second time within 10 days. The LEFS-Ar floor and ceiling effects, internal consistency, test–retest reliability, measurement error, and construct validity were examined. Results The LEFS-Ar had excellent internal consistency with Cronbach’s alpha of 0.95 and excellent test–retest reliability (ICCagreement=0.91) with no floor and ceiling issues. Standard error of measurement was 4.78 points while the minimal detectable change at 90% confidence was 11.15 points. Consistent with our hypotheses, the LEFS-Ar scores correlated significantly with 6MWT (r= −0.66, p < 0.001), activity domain of the SGRQ (r = 0.55, p < 0.001), and were significantly different according to COPD disease severity (p= 0.02). Conclusions In people with COPD, the LEFS-Ar has excellent reliability with no floor or ceiling effects. The LEFS-Ar demonstrated evidence supporting its validity as a measure of activity limitation that can be used in clinical practice and in research studies. Implications for rehabilitation The Arabic version of the Lower Extremity Functional Scale (LEFS-Ar) is a reliable measure in people with chronic obstructive pulmonary disease (COPD). Rehabilitation specialists can use the LEFS-Ar to validly measure activity limitation in people with COPD.