Factor Structure of McGill Quality of Life Questionnaire in Patients with Heart Disease: Second-order Confirmatory Factor Analysis

The effect of heart diseases on the quality of life is the issue needs attention of health care providers. Improving quality of life is considered as the goals of rehabilitative therapies. This study conducted to evaluate the McGill Quality of Life Questionnaire in patients with heart diseases.
In this cross-sectional study, 500 patients with heart diseases were recruited from BooAli Sina Hospital and Velayat Hospital affiliated with Qazvin University of Medical Sciences from May to August 2016. The participants completed the McGill Quality of Life Questionnaire. The construct validity (including convergent and discriminant validity) and Reliability using the Cronbach’s alpha, theta, and McDonald's Omega of the McGill Quality of Life Questionnaire were evaluated. The structure of the Questionnaire was assessed using factor analysis.
Three factors, including overall view of the quality of life, physical aspect, and psychological dimension, were extracted. Model fit indexes confirmed a good fit of he McGill Quality of Life Questionnaire (Comparative of Fit Index: CFI=.918, incremental fit index: IFI=.919, Adjusted Goodness of Fit Index: AGFI=.844, RMSEA=.079, Minimum Discrepancy Function by Degrees of Freedom divided: CMIN/DF=2.97, Parsimonious Normed Fit Index: PNFI=.681, Parsimonious Comparative Fit Index: PCFI=.709). Convergent and divergent validity, internal consistency, and construct reliability of the questionnaire were confirmed.
The findings revealed that the three-factor model of the McGill Quality of Life Questionnaire has satisfactory validity and reliability. Thus, this questionnaire can be used in future studies to assess the quality of life of patients with heart diseases.