More comprehensively measuring quality of life in life-threatening illness: the McGill Quality of Life Questionnaire - Expanded

Background: Domains other than those commonly measured (physical, psychological, social, and sometimes existential/spiritual) are important to the quality of life of people with life-threatening illness. The McGill Quality of Life Questionnaire (MQOL) - Revised measures the four common domains. The aim of this study was to create a psychometrically sound instrument, MQOL - Expanded, to comprehensively measure quality of life by adding to MQOL-Revised the domains of cognition, healthcare, environment, (feeling like a) burden, and possibly, finance.

Methods: Confirmatory factor analyses were conducted on three datasets to ascertain whether seven new items belonged with existing MQOL-Revised domains, whether good model fit was obtained with their addition as five separate domains to MQOL-Revised, and whether a second-order factor representing overall quality of life was present. People with life-threatening illnesses (mainly cancer) or aged > 80 were recruited from 15 healthcare sites in seven Canadian provinces. Settings included: palliative home care and inpatient units; acute care units; oncology outpatient clinics.

Results: Good model fit was obtained when adding each of the five domains separately to MQOL-Revised and for the nine correlated domains. Fit was acceptable for a second-order factor model. The financial domain was removed because of low importance. The resulting MQOL-Expanded is a 21-item instrument with eight domains (fit of eight correlated domains: Comparative Fit Index = .96; Root Mean Square Error of Approximation = .033).

Conclusions: MQOL-Expanded builds on MQOL-Revised to more comprehensively measure the quality of life of people with life-threatening illness. Our analyses provide validity evidence for the MQOL-Expanded domain and summary scores; the need for further validation research is discussed. Use of MQOL-Expanded will enable a more holistic understanding of the quality of life of people with a life-threatening illness and the impact of treatments and interventions upon it. It will allow for a better understanding of less commonly assessed but important life domains (cognition, healthcare, environment, feeling like a burden) and their relationship to the more commonly assessed domains (physical, psychological, social, existential/spiritual).