Fig. 3: PpgAge predictions of chronological age.
From: A wearable-based aging clock associates with disease and behavior
a–d Wearable PPG segments (minimum 30 segments over a 30-day span) predict chronological age with a mean absolute error of 2.42 years (95% CI 2.30–2.54) and 2.45 years (95% CI 2.22–2.71) in healthy male and female test participants, respectively (dashed line is the identity). In the general population, prediction errors are 3.13 years (95% CI 3.11–3.15) and 3.26 years (95% CI 3.24–3.29) for male and female participants, respectively. Analysis was restricted to participants with chronological age between 18 and 85, as participants older than 75 are rare in the healthy training cohort. e Within the healthy cohort, predictions error remains relatively stable across demographic categories —biological sex (first panel), BMI (second panel), and self reported race/ethnicity (third panel). Younger participants enjoy a modestly lower error than older participants (fourth panel), which may be partially explained by a lower expectation of misdiagnosis and therefore more accurate “healthy” labels. Within the general cohort, prediction error is systematically higher and more variable, as expected as non-healthy participants were not used for training. Error bars are 95% confidence intervals computed from 1000 bootstrap replicates.
