title: The frailty index outperforms DNA methylation age and its derivatives as an indicator of biological age.
abstract: The measurement of biological age as opposed to chronological age is important to allow the study of factors that are responsible for the heterogeneity in the decline in health and function ability among individuals during aging. Various measures of biological aging have been proposed. Frailty indices based on health deficits in diverse body systems have been well studied, and we have documented the use of a frailty index (FI34) composed of 34 health items, for measuring biological age. A different approach is based on leukocyte DNA methylation. It has been termed DNA methylation age, and derivatives of this metric called age acceleration difference and age acceleration residual have also been employed. Any useful measure of biological age must predict survival better than chronological age does. Meta-analyses indicate that age acceleration difference and age acceleration residual are significant predictors of mortality, qualifying them as indicators of biological age. In this article, we compared the measures based on DNA methylation with FI34. Using a well-studied cohort, we assessed the efficiency of these measures side by side in predicting mortality. In the presence of chronological age as a covariate, FI34was a significant predictor of mortality, whereas none of the DNA methylation age-based metrics were. The outperformance of FI34over DNA methylation age measures was apparent when FI34and each of the DNA methylation age measures were used together as explanatory variables, along with chronological age: FI34remained significant but the DNA methylation measures did not. These results indicate that FI34is a robust predictor of biological age, while these DNA methylation measures are largely a statistical reflection of the passage of chronological time.
authors.affiliation: Tulane Center for Aging and Department of Medicine, Tulane University Health Sciences Center, Box 8513, 1430 Tulane Ave., New Orleans, 70112, LA, USA. skim5@tulane.edu.
authors.forename: Sangkyu
authors.identifier: 0000-0001-6761-2579
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Global Biostatistics and Data Science, School of Public Health and Tropical Medicine, Tulane University Health Sciences Center, New Orleans, LA, USA.
authors.forename: Leann
authors.initials: L
authors.lastname: Myers
authors.affiliation: Tulane Center for Aging and Department of Medicine, Tulane University Health Sciences Center, Box 8513, 1430 Tulane Ave., New Orleans, 70112, LA, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Wyckoff
authors.affiliation: Department of Psychology, Louisiana State University, Baton Rouge, LA, USA.
authors.forename: Katie E
authors.initials: KE
authors.lastname: Cherry
authors.affiliation: Tulane Center for Aging and Department of Medicine, Tulane University Health Sciences Center, Box 8513, 1430 Tulane Ave., New Orleans, 70112, LA, USA.
authors.forename: S Michal
authors.initials: SM
authors.lastname: Jazwinski
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics*; D015331:Cohort Studies; D019175:DNA Methylation / Q000235:genetics*; D005260:Female; D000073496:Frailty / Q000235:genetics*; D015577:Geriatric Assessment / Q000379:methods; D006801:Humans; D008136:Longevity / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends*; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models
keywords: Aging; Biological age; DNA methylation; Frailty; Mortality