Table 2.

Studies selected for review pertaining to allostatic load indices and composite biomarkers of aging.

Allostatic Load/Composite Biomarkers
Study Title	BA Predictor Used	Cohort name (if applicable)	n	Results
Reduction in allostatic load in older adults is associated with lower all-cause mortality risk: MacArthur studies of successful aging.	Allostatic load index		171	Adjusted for age and baseline allostatic load, each unit increment in the allostatic load change score was associated with mortality odds ratio of 3.3 (95% confidence interval, 1.1–9.8) (Karlamangla et al., 2006)
Allostatic load and subsequent all-cause mortality: Which biological markers drive the relationship? Findings from a UK birth cohort	Allostatic load index	1958 British birth cohort	8113	Hazard ratios for participants with a mid (3 ≤ AL < 5) and high AL (≥5) were 1.98 (1.25–3.13) and 3.56 (2.2–5.53), respectively, and were found to be significantly greater than in participants with a low AL (<3) (Castagné et al., 2018)
An epigenetic biomarker of aging for lifespan and healthspan	Phenotypic age estimator	Third and fourth National Health and Nutrition Examination Survey	9926, 6209	A one-year increase in phenotypic age is associated with a 9% increase in the risk of all-cause mortality (HR = 1.09, p = 3.8E-49), a 9% increase in the risk of mortality from aging-related diseases (HR = 1.09, p = 4.5E-34), a 10% increase in the risk of CVD mortality (HR = 1.10, p = 5.1E-17), a 7% increase in the risk of cancer mortality (HR = 1.07, p = 7.9E-10), a 20% increase in the risk of diabetes mortality (HR = 1.20, p = 1.9E-11), and a 9% increase in the risk of chronic lower respiratory disease mortality (HR = 1.09, p = 6.3E-4) (Levine et al., 2018)