Psychometric testing of the Caregiver Quality of Life Index-Cancer scale in an Iranian sample of family caregivers to newly diagnosed breast cancer women

Abstract

Aim: To translate and test the reliability and validity of the Persian version of the Caregiver Quality of Life Index-Cancer scale.

Background: Research across many countries has determined quality of life of cancer patients, but few attempts have been made to measure the quality of life of family caregivers of patients with breast cancer. The Caregiver Quality of Life Index-Cancer scale was developed for this purpose, but until now, it has not been translated into or tested in the Persian language.

Design: Methodological research design.

Methods: After standard translation, the 35-item Caregiver Quality of Life Index-Cancer scale was administered to 166 Iranian family caregivers of patients with breast cancer. A confirmatory factor analysis was carried out using LISREL to test the scale's construct validity. Further, the internal consistency and convergent validity of the instrument were tested. For convergent validity, four instruments were used in the study: sense of coherence scale, spirituality perspective scale, health index and brief religious coping scale.

Results: The confirmatory factor analysis resulted in the same four-factor structure as the original, though, with somewhat different item loadings. The Persian version of the Caregiver Quality of Life Index-Cancer scales had satisfactory internal consistency (0·72-0·90). Tests of convergent validity showed that all hypotheses were confirmed. A hierarchical multiple regression analysis additionally confirmed the convergent validity between the total Caregiver Quality of Life Index-Cancer score and sense of coherence (β = 0·34), negative religious coping (β = -0·21), education (β = 0·24) and the more severe stage of breast cancer (β = 0·23), in total explaining 41% of the variance.

Conclusion: The Persian version of the Caregiver Quality of Life Index-Cancer scale could be a reliable and valid measure in Iranian family caregivers of patients with breast cancer.

Relevance to clinical practice: The Persian version of the Caregiver Quality of Life Index-Cancer scale is simple to administer and will help nurses to identify the nursing needs of family caregivers.