Persian version of the brief Older People's Quality of Life questionnaire (OPQOL-brief): the evaluation of the psychometric properties

Abstract

Background and objectiveQuality of life (QoL) is a multi-dimensional concept and its assessment is one of important themes of care for older people. Assessing QoL in older people needs specific scales. The aim of this study was to culturally adapt and investigate the psychometric properties of the Persian version of brief Older People's Quality of Life questionnaire (OPQOL-brief) in an Iranian older population.MethodsThis methodological cross-sectional study was conducted among 525 Persian-speaking older people (aged 60 and over), living in Isfahan, Iran. Translation of the OPQOL-brief questionnaire was performed using forward-backward method. Test-retest reliability was evaluated through Intra Class Correlation (ICC) coefficient and internal consistency by using Cronbach's alpha. Construct validity was investigated by using exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and Latent class analysis (LCA). Criterion, convergent and discriminant validities were also assessed.ResultsPersian version of the OPQOL-brief showed good test-retest reliability (ICC=0.842, 95 CI=0.73-0.91; P<0.001). Persian OPQOL-brief scale demonstrated high internal consistency (Cronbach's <alpha>=0.83). It showed good discriminant validity and differentiated old patients from healthy older individuals (P<0.001). Construct validity based on EFA led to extraction of three dimensions ("socioeconomic", "emotional", and "physical" well-being) and the CFA confirmed the adequacy of extracted construct from EFA (CFI=0.909, PCFI=0.52, PNFI=0.5, CMIN/DF=3.012, and RMSEA=0.08). LCA classified participants into three classes in terms of QoL level (low (16), middle (67), and high (17)). Criterion validity and convergent validity revealed significant positive correlations between OPQOL-brief and physical and psychological dimensions of the SF-36. ConclusionThe Persian version of the OPQOL-brief is a reliable and valid instrument for assessing QoL with applicability in a broad range of older Persian language population.