Translation and validation of the Arab version of the Late-Life Function and Disability Instrument: a cross sectional study

BACKGROUND The Late-Life Function and Disability Instrument (LLFDI) provides a comprehensive, reliable, and valid assessment of physical function and disability in community-dwelling adults. There does not appear to be a validated, comprehensive instrument for assessing function and disability in Arabic. The objective of the present study was to translate and culturally adapt the LLFDI to Arabic, and to determine its test-retest reliability and validity. METHODS The LLFDI was translated to Arabic through a forward and backward translation process, and approved by a bilingual committee of experts. Sixty-one (26 male and 35 female) Arabic speaking, healthy, older adults, ages 65-88, living in northern Israel participated in the study. To determine test-retest reliability, the questionnaire was administered twice to 41 subjects with a 6 to 8day interval. Construct validity was examined by correlating the LLFDI responses with the 10-item physical function (PF-10) subscales of the General Health Survey (SF-36), with the physical component of SF-36 (SF-36 PCS), and with two performance measures, the Berg Balance Scale (BBS) and Time Up and Go (TUG) test. Additionally, gender and fall related differences in the LLFDI were also examined. RESULTS Internal consistency (Cronbach's alpha) was good to excellent (0.77 to 0.97). Test-retest agreement was good to very good (function component: 0.86-0.93, disability component: 0.77-0.93). Correlation with the SF-36 PCS and PF-10 was moderate to strong for both LLFDI components (function, r = 0.53-0.65 and r = 0.57-0.63, and LLFDI disability, r = 0.57-0.76 and 0.53-0.73, respectively). Significant, moderate-to-strong correlations between the LLFDI and BBS (r = 0.73-0.87) and a significant, moderate, negative correlation between LLFDI and TUG test (r = -0.59- -0.68) were noted. The standard error of measure was 6-12%, and the smallest real difference was 18-33%. Discriminative validity for both gender and fall status were also demonstrated. CONCLUSIONS The Arabic version of the LLFDI is a highly reliable and valid instrument for assessing function and disability in community dwelling, Arab older adults. The translated instrument has a discriminative ability between genders and between fallers and non-fallers. The translated instrument may be used in clinical settings and for research purposes.