Development and testing of reliability and validity of a subjective QOL scale for older adults perceiving a dynamic healthy life through the three dimensions of biological life, everyday life, and overall course of life

Abstract

Objectives To develop and assess the reliability and validity of a scale measuring subjective quality of life (QOL), which encompasses the "strength and ability" to live positively through the three dimensions of biological life, everyday life, and overall course of life, in order to support QOL in older adults.Methods We reviewed related literature and conducted interviews with patients with chronic diseases. Participants rated their QOL on a seven-point scale using the visual analog scale. Interviewer-administered questionnaires were used to collect data from 100 older adults living in their own homes. The participants were between the ages of 70 and 84, and were recruited from comprehensive community support centers or from among hospital outpatients. We assessed scale reliability using Cronbach's α, item-total (I-T) correlation analysis, and calculation of α coefficient-if-item-deleted. We examined content validity by analyzing the content of the free response items. To evaluate construct validity, we carried out a hierarchical multiple regression analysis, examined the semantic content of the factors related to subjective QOL, and confirmed consistency with previous studies.Results Regarding the reliability analysis of the scale, the α coefficient was 0.898, and both the I-T correlation and α coefficient-if-item-deleted exceeded the minimum value considered reliable. In examining content validity, the categories extracted for each of the three dimensions were found to demonstrate the characteristics of the general ideas of each dimension of QOL. Thus, the scale was confirmed to have overall content validity. As for the assessment of validity of its constitutive concepts, subjective QOL scores were significantly high among participants who had jobs, had role-related or financial capacity, used two or more nursing services, or scored high in perceived health competence, social networking, and sense of coherence (SOC). In addition, "meaningfulness" of SOC, and financial capacity had significant correlations with subjective QOL. These results are consistent with past research and therefore confirm construct validity.Conclusion This study sufficiently confirmed the reliability and validity of the scale, and consequently its usability.