Can markers of biological age predict dependency in old age?

Abstract

Recent research has shown that markers of biological age, such as leukocyte telomere length (LTL), epigenetic clocks and the frailty index (FI) are predictive of mortality and age-related diseases. However, whether these markers associate with the need for care in old age, thereby having utility in reflecting dependency, is unclear. This study was undertaken to analyze whether LTL, two epigenetic clocks-the DNA methylation age (DNAmAge) and DNAm PhenoAge-and the FI are associated with the need for regular care in up to 604 individuals (aged 48-94 years) participating in the Swedish Adoption/Twin Study of Aging. Need for regular care was defined as receiving formal or informal help in daily routines at least once per week. Logistic regression adjusted for age, sex and education was used in the analysis. The predictive accuracies, assessed as the area under the curve (AUC) for the significant biological age measures were further compared to the accuracies of the limitations in activities of daily living (ADL) and instrumental ADL (IADL). Neither LTL nor the epigenetic clocks were associated with the need for care, whereas the FI was; odds ratio for 10% increase in FI 3.54 (95% confidence interval 2.32-5.41). The FI also demonstrated higher predictive accuracy than the ADL score (FI AUC 0.80 vs. ADL score AUC 0.62; p < 0.001 for equality of the AUCs), whereas the difference between FI AUC (0.80) and IADL score AUC (0.75) was not significant (p = 0.238). The FI might thus be a useful marker for the need for care.

Keywords: ADL; Epigenetic clock; Frailty index; Leukocyte telomere length; Need for care.

Fig. 1

Distributions of the frailty index (a) and age (b) according by the amount of care needed. For the frailty index, differences in distributions were significant across all groups. For age, the difference was significant only between those not needing care at all and those needing care once or twice per week

Fig. 2

Predictive accuracies for the 29-item FI, the ADL and IADL scores for predicting dependency. Test for the equalities between the FI and ADL score AUC/ROCs indicated that the FI demonstrated significantly better predictive accuracy (p < 0.001) whereas the difference between the FI and IADL score AUC/ROCs was not statistically significant (p = 0.238). Abbreviations: ADL, activities of daily living; AUC, area under the curve; IADL, instrumental activities of daily living; FI, frailty index; ROC, receiver operating characteristic