Validity of the McGill Quality of Life Questionnaire in the palliative care setting: a multi-centre Canadian study demonstrating the importance of the existential domain.

This study was carried out in eight palliative care services in four Canadian cities. A revised version of The McGill Quality of Life Questionnaire (MQOL) is compared to a single-item scale measuring overall quality of life (SIS), and the self-administered version of the Spitzer Quality of Life Index (SA-QLI), to obtain evidence of validity. MQOL total score predicts SIS better than does SA-QLI, although much of the variance remains to be explained. The results of principal components analysis of data using this revised version of MQOL are similar to those from previous MQOL studies with different patient populations. The MQOL subscales, constructed on the basis of principal components analysis, demonstrate acceptable internal consistency reliability. The MQOL measures reflecting physical well-being and existential well-being are important for predicting SIS.