Successful ageing trajectories at the end of life: a longitudinal population-based cohort study

Abstract

BackgroundDespite the acknowledgment that successful ageing is a heterogeneous life-course process, present models of successful ageing are unable to accommodate decline at the end of life because of methodological and conceptual limitations. The present study aimed to address these limitations, identifying different trajectories of successful ageing at the end of life. MethodsThe Successful Ageing Index (SAI), which is a scale consisting of components identified by systematic reviews of layperson perspectives and operational definitions of successful ageing, was collected in a longitudinal population-based cohort study of individuals aged 75 years and older—the Cambridge City over-75s Cohort Study (CC75C). SAI scores were examined longitudinally with growth mixture modelling (GMM) to identify classes of participants with similar trajectories; in this model decedents’ (n=1015) last completed interview and up to four previous data collection waves before death were used. Classes identified by GMM were compared by means of logistic regression models. FindingsA three-class model was identified: a high-functioning, no decline (HN) class; a high-functioning, gradual decline (HG) class; and a low-functioning, steep decline (LS) class. Individuals in the HN class were significantly younger at death (88·3 years [SD 4·9]) than were those in the HG (89·9 [5·0], p<0·0001) and LS classes (90·5 [5·1], p<0·0001); were significantly younger at their last interview (82·9 years [3·6] vs 85·0 [4·2] in the HG class [p<0·0001] and 86·3 [4·7] in the LS class [p<0·0001]); consisted of more men (52% men vs 31% in the HG class [p<0·0001] and 22% in the LS class [p<0·0001]); and were more likely to be married (51% vs 24% in the HG class [p<0·0001] and 19% in the LS class [p=0·0001]). InterpretationSuccessful ageing trajectories at the end of life are heterogeneous; individuals can experience many different trajectories towards death. Methods used in this study provide novel insights into successful ageing at the end of life. The present study provides the methodological framework for future research, with important implications for policy and practice, as well as insights into the demographic characteristics of end of life trajectories. FundingNone.