Background: The worries of next of kin about their older loved ones in nursing homes can be extensive and can adversely affect their subjective experiences of their own physical, mental and social well-being. It is thus of utmost importance to measure the quality of life of next of kin in a valid and reliable way.
Methods: The design is a cross-sectional study with psychometric evaluation based on classical test theory in preparation for a planned educational intervention study on palliative care. An abbreviated version of the World Health Organization's quality-of-life self-assessment instrument WHOQOL, the Swedish WHOQOL-BREF, was completed by 254 next of kin of older persons in 30 nursing homes. Data quality was assessed via the mean, median, item response, missing values, and floor and ceiling effects. Reliability was estimated using Cronbach's alpha and corrected item-total correlations. Construct validity was estimated by Spearman's rank correlation, and model fit was assessed using confirmatory factor analysis.
Results: The rate of missing data was low (less than 2%). Ceiling effects ranged from 11 to 43% and were above 20% for 21 of 24 items. The corrected item-total correlations varied between 0.35 and 0.68 and were thus well above the lower limit of 0.30. Cronbach's alpha was 0.83, indicating satisfactory internal consistency. The confirmatory factor analysis indicated a fair to close model fit (comparative fit index 0.93, root mean squared error of approximation 0.06).
Conclusions: The findings suggest that the WHOQOL-BREF may constitute a reliable and valid measure of quality of life for use among next of kin to older persons in nursing homes. When interpreting the results, it is important to assess the ceiling effect, as it may restrict the ability of the WHOQOL-BREF to detect true positive changes in quality of life over time.
Trial registration: NCT02708498.
Keywords: Confirmatory factor analysis; Factor analysis; Quality of life.