Background: The proportion of older people aged more than 65 years old is continuously increasing in the world population. The quality of life is an important factor in their biopsychosocial handling. The questionnaire “Older People’s Quality of Life-35” (OPQOL-35) has been specially developed for the assessment of the senior’s quality of life. The aim of this study is to translate and evaluate the psychometric properties of the transcultural Swiss French version of the OPQOL-35 questionnaire (OPQOL-35-SF).
Method: Forward-backward procedure was applied to translate the original questionnaire from English into Swiss French. Then, a sample of older people completed the questionnaire. The construct validity was evaluated by comparing the results of the OPQOL-35-SF with the scores of three other questionnaires (WHOQOL-OLD, CASP-12 and EQ-5D-5L) and two visual analogue scales (health and quality of life). The questionnaire’s structure has been assessed through exploratory and confirmatory factor analysis. The OPQOL-35-SF questionnaire was submitted a second time after 7 to 23 days to evaluate the reliability.
Results: 264 older people completed all the questionnaires once and 262 the OPQOL-35-SF a second time. The mean age of participants was 76.8 (SD = 7.1). Most of them were women (73,9%). KMO is of 0.86 and the Bartlett’s test of sphericity is significant (p<0.001). The result of EFA shows 8 factors with eigenvalues greater than one, which explained 58% of the observed variance. All the items have a significant impact (<0.30) in at least one factor. The convergent validity presents low to moderate correlations (rho: 0.384-0.663). Internal consistency is good with a Cronbach’s alpha at 0.875 for test and at 0.902 for retest. Test-retest reliability presents an ICC2.1 at 0.83 (IC 0.78 to 0.87).
Conclusion: The Swiss French version of the questionnaire OPQOL-35 shows psychometric properties which permit its use in the clinical practice or for research purposes. A supplementary sample would be necessary for a better repartition of the items in the different factors.