Psychometric testing of the translated McGill Quality of Life Questionnaire-Taiwan version in patients with terminal cancer

Abstract

Background and purpose: Quality of life (QOL) is the paramount goal of end-of-life care. However, there is no Chinese language instrument for measuring QOL that has been shown to have adequate psychometric properties for Taiwanese patients with terminal cancer. The purpose of this study was to examine the psychometric properties of a Chinese language version of the McGill Quality of Life questionnaire (MQOL-Taiwan version) in this population.

Methods: The original English version of the MQOL questionnaire was translated into Chinese, and administered to 64 Taiwanese patients with terminal cancer for psychometric testing (factor structures and various types of reliability and validity). The cultural equivalence of the translation was tested by content validity index. Statistical analysis included exploratory factor analysis, Pearson's product moment correlation coefficient, and the calculation of Cronbach's alpha (alpha).

Results: Findings on the validity and reliability of the MQOL-Taiwan version were as follows. The value of content validity was 0.98. The range of the correlations between an item and its domain was 0.59 to 0.96 (all p < 0.05), and for inter-domain was 0.28 to 0.52 (all p < 0.05). The 4 domains of the original MQOL emerged as the 4 dominant factors (64% total variance explained) in the MQOL-Taiwan version, namely the domains of physical symptoms, psychological symptoms, existential well-being, and support. The internal consistency (Cronbach's alpha) coefficient of the whole MQOL-Taiwan version was 0.83, and those for the 4 domains ranged from 0.69 to 0.90. For the convergent and divergent validity, the MQOL-Taiwan version physical domain was moderately and significantly (r = -0.44, p < 0.05) correlated with the performance status rating of the Eastern Cooperative Oncology Group-Performance Status Rating (ECOG-PSR). The MQOL-Taiwan version psychological, existential, and support domains were not significantly correlated to the ECOG-PSR.

Conclusions: The MQOL-Taiwan version demonstrated an acceptable level of reliability, validity and equivalency in the initial cross-cultural validation. These findings indicate the suitability of this QOL measure for clinical and research use in Taiwanese patients with terminal cancer.