Reliability and validity of a self-rated analogue scale for global measure of successful aging

Objective: Dimension-specific objective measures are criticized for their limited perspective and failure to endorse subjective perceptions by respondents, but the validity and correlates of a subjective global measure of successful aging (SA) are still not well established. We evaluated the reliability and validity of a self-rated analogue scale of global SA in an elderly Singaporean population. Design: Cross-sectional data analysis using a comprehensive questionnaire survey. Participants and setting: 489 community-dwelling Singaporeans aged 65 years and over. Measurements: Self-rated SA on an analogue scale from 1 (least successful) to 10 (most successful) was analyzed for its relationship to criterion-based measures of five specific dimensions (physical health and function, mental well-being, social engagement, psychological well-being, and spirituality/religiosity), as well as outcome measures (life satisfaction and quality of life). Results: Self-rated SA was significantly correlated to measures of specific dimensions (standardized β from 0.11 to 0.39), most strongly with psychological functioning (β = 0.391). The five dimension-specific measures together accounted for 16.7% of the variance in self-rated SA. Self-rated SA best predicted life satisfaction (R² = 0.26) more than any dimension-specific measure (R² from 0.05 to 0.17). Self-rated SA, vis-à-vis dimension-specific measures, was related to a different set of correlates, and was notably independent of chronological age, sex, education, socioeconomic status, and medical comorbidity, but was significantly related to ethnicity. Conclusion: The self-rated analogue scale is a sensitive global measure of SA encompassing a spectrum of underlying dimensions and subjective perspectives and its validity is well supported in this study.