Using Perceived Health to Test the Construct-related Validity of Global Quality of Life

Quality of life (QOL) is considered as aglobal, yet unidimensional, subjectiveassessment of one's satisfaction with life. Weexamine the construct validity of the availableindicators of global QOL by constructing acausal model in which QOL is viewed as causallyresponding to several dimensions of perceivedhealth. Global QOL is measured with fiveindicators derived from the literature, andperceived health is measured by eightdimensions of the SF-36 Health Survey. Thestructural equation model describes the QOL andperceived health assessments of 306 coronaryartery bypass graft (CABG) patients andprovides a stringent test of theunidimensionality of the global QOL indicators.The evidence regarding QOL is worrisome, butnot devastating. The acceptable model fit wasachieved by introducing direct effects leadingfrom the General Health Perceptions concept totwo of the five indicators of global QOL. Thissuggests that there are some mechanisms thatinfluence these indicators without firstaltering QOL, or that these indicators are notresponding in unison to QOL. Furthermore, theFaces QOL indicator required measurement errorcorrelations to two of the perceived healthindicators. This also suggests that there aremechanisms beyond pure QOL that act upon thisindicator. But the problematic effects anderror correlations are modest, so the evidenceagainst these indicators is not particularlystrong. Overall, the Self-Anchoring StrivingScale (SASS) indicator and the Life-as-a -Wholeindicator (from Multiple Discrepancies Theory)seem to be the cleanest indicators of globalQOL. General health perceptions and perceivedmental health both influenced global QOL, whilethe other six health perception concepts had noconsistent impact on global QOL.