Quality of life in older age: evidence from an Irish cohort study.

OBJECTIVES: To compare the role of different life domains in determining quality of life (QoL) in Ireland with international results.
DESIGN: Cross-sectional study of responses to The Irish Longitudinal Study of Ageing.
SETTING: Individuals aged 50 and older living in private residential addresses in the Republic of Ireland. PARTICIPANTS: Eight thousand five hundred four individuals living in 6,279 households in the Republic of Ireland (response rate 62%) were interviewed and completed a self-completion questionnaire. MEASUREMENTS: Quality of life was measured using the Control, Autonomy, Self-realization and Pleasure measure (CASP-19). The domains of physical and mental health, social participation, economic resources, and sociodemographic status were measured using a large number of indicators. Ordinary least squares regression models were used to estimate the effect of factors on CASP-19, with the relative contribution of different domains to total explanation measured using a measure of statistical fit.
RESULTS: The mean CASP-19 score for the sample was 43.8 (95% confidence interval = 43.6-44.1), significantly higher than the mean score for the English Longitudinal Study of Ageing (mean 42.5: 42.3-42.7). In unadjusted analyses, CASP-19 was curvilinear with age, peaking at 67 and falling thereafter. Controlling for predictors of QoL, CASP-19 continued to rise, at a decreasing rate, with age. Mental health independently explained the largest proportion of variance in CASP-19 (7.6%), but no single domain of life dominated in terms of explanation.
CONCLUSION: Increasing longevity can be associated with increasing QoL as long as it is accompanied by reasonable levels of mental and physical health, high-quality relationships, and social participation. Even if physical health becomes poor, evidence suggests that QoL can often remain high as individuals find value and enjoyment in other dimensions of life.