Sustained informal care: The feasibility, construct validity and test-retest reliability of the CarerQol-instrument to measure the impact of informal care in long-term care

Objectives: This study analyses feasibility, construct validity and test-retest reliability of the Care-related Quality of Life (CarerQol)-instrument among informal caregivers of long-term care (LTC) users. The CarerQol measures the impact of informal care by assessing happiness (CarerQol-VAS) and describing burden dimensions (CarerQol-7D). Methods: Data was gathered among informal caregivers of patients obtaining day care or living in a LTC facility in the Netherlands with two questionnaires sent with a two-week interval (n test = 108, n retest = 100). Percentages of missing values indicated feasibility of the CarerQol. Construct validity assessed the extent to which differences in background characteristics were reflected in happiness scores (CarerQol-VAS) with univariate and multivariate statistics. Additionally, construct validity was tested with assessing the correlation between the CarerQol and the Self-Rated Burden (SRB) scale. Percentages of complete agreement between CarerQol scores at test and retest, Cohen's kappa coefficients (kappa value) and Intraclass Correlation Coefficients (ICCs) were used to assess reliability. Results: In this study, 3.7% was missing on the CarerQol. CarerQol-VAS was positively associated with caregivers' age and health, and negatively with SRB score. The percentage of complete agreement of CarerQol-VAS between the measure moments was 60% and between 76% and 96% for CarerQol-7D. kappa value and ICC of CarerQol-VAS were 0.52 and 0.86, and ranged between 0.55 and 0.94 for CarerQol-7D. Conclusion: The CarerQol measures the impact of informal care among carers of LTC users in a feasible, valid and reliable way.