Reliability and Validity of Turkish Version of the Caregiver Quality of Life Index Cancer Scale

Abstract

Measuring effects of cancer on family caregivers is important to develop methods which can improve their quality of life (QOL) . Nevertheless, up to now, only a few tools have been developed to be used in this group. Among those, the Caregiver Quality of Life Index-Cancer Scale (CQOLC) has met minimum psychometric criteria in different populations in spite of conflicting results. The present study was conducted to evaluate reliability and validity of CQOLC among Turkish cancer family caregivers. The CQOLC was administered to 120 caregivers, along with Beck Depression Inventory (BDI), Medical Outcomes Study MOS 36- Item Short Form Health Survey (SF-36), State-Trait Anxiety Inventory (STAI), and Multidimensional Scale of Perceived Social Support (MSPSS). Internal consistency and test-retest stability were used to investigate reliability. Construct validity was examined by using known group method, convergent, and divergent validity. For the known group method, we hypothesized that CQOLC scores would differ between depressed and non-depressed subjects. We investigated convergent validity by correlating scores for CQOLC with scores for other similar measures including SF-36 and STAI. The MSPSS was completed at the same time as CQOLC to provide divergent validity. The values for internal consistency and test-retest correlation were 0.88 and 0.96, respectively. The CQOLC discriminated those who were depressed from those who were not. Convergent validity supported strong correlations between CQOLC scores and two main component scores (PCS, MCS) in SF-36 although there was a weak correlation between CQOLC and STAI scores. Regarding divergent validity, the correlation between CQOLC and MSPSS was in the low range, as expected. The Turkish CQOLC is a reliable and valid tool and it can be utilized to determine QOL of family caregivers.