Biological-age tests compared
“Biological age” can mean different measurements. Clinical Phenotypic Age uses blood biomarkers and your age; DNAm PhenoAge and the original Horvath clock use DNA methylation. DunedinPACE estimates a rate of aging, not an age in years. Check the named algorithm before comparing two numbers.
Four methods, different inputs and targets
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| Method | Inputs | What the model estimates |
|---|---|---|
| Clinical Phenotypic Age | Nine clinical biomarkers plus chronological age | A mortality-risk-based age estimate, in years |
| DNAm PhenoAge | DNA methylation at 513 sites | A methylation estimate of Phenotypic Age |
| Original Horvath clock | DNA methylation at 353 sites | Age from a model trained on chronological age |
| DunedinPACE | Blood DNA methylation at 173 sites | Pace of aging, not age in years |
PhenoAge does not always mean a DNA test
The original paper has two steps. First it combines nine clinical biomarkers with chronological age to estimate Phenotypic Age. It then trains a DNA-methylation model to predict that measure. The second model is DNAm PhenoAge. A report that omits “DNAm” may be referring to the clinical calculation, so ask which inputs were actually used.
Why a single blood sample can represent a rate
The DunedinPACE developers first modelled change in 19 organ-system indicators measured at ages 26, 32, 38 and 45. They then trained a DNA-methylation algorithm to estimate that longitudinal pattern from blood. The rate interpretation comes from its training target, not from taking several blood samples every time the test is used.
What to look for on a test report
Identify the named algorithm, the sample used and the units of the output before comparing two reports. The paper makes clear that DunedinPACE complements other methylation clocks rather than being the same measurement under another brand. A lower number across two different algorithms is not automatically an improvement.
Use the table and its sources
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Source-linked editorial synthesis, prepared with AI assistance. This is not a clinician review or a personalised treatment recommendation. Corrections: editorial standards.