Rulers & endpoints
Expert panels, regulators and trial designers do not agree on how to measure aging. Each measure gets one row showing where it stands with each of them, side by side. Nothing is ranked or combined into a score, because that would quietly pick one view as the right one.
11endorsed by the panel, no regulatory standing12regulatory standing, not endorsed for aging40/41no published within-person reliability10.1xmore trials measure function than epigenetic age
The rulers
Every ruler either the expert panel or the regulator names. The union, not the overlap: the rulers only one institution names are the finding. A panel verdict comes from the Perri 2025 Delphi consensus; regulatory standing is read live from the compiled FDA surrogate table, never transcribed.
| Ruler | Expert panel | Regulator | Trials measuring | Can it measure one person? |
|---|---|---|---|---|
| Panel-endorsed and regulator-mapped9 rulers | ||||
| Grip strength / muscle function | endorsed | no standing | 250 | unknown |
| Frailty index | endorsed | no standing | 169 | unknown |
| Cognitive function | endorsed | no standing | 161 | unknown |
| Gait / walking speed | endorsed | no standing | 116 | unknown |
| Blood pressure | endorsed | FDA surrogate validated for Hypertension, Hypotension, Interoperative hemorrhage | 41 | unknown |
| Inflammatory markers (IL-6, CRP, TNF-alpha) | endorsed | no standing | 32 | unknown |
| Epigenetic / biological age clock | endorsed | no standing | 30 | cannot detect small change Deviations of up to 9 years between technical replicates across six prominent clocks. |
| Fasting / postprandial glucose | declined | no standing | 23 | unknown |
| Glycated haemoglobin (HbA1c) | declined | FDA surrogate validated for Type 2 diabetes mellitus | 19 | unknown |
| Panel-evaluated, no canonical endpoint7 rulers | ||||
| Muscle mass | endorsed | no canonical endpoint | not classified | unknown |
| Standing balance test (SBT) | endorsed | no canonical endpoint | not classified | unknown |
| Timed-Up-and-Go (TUG) | endorsed | no canonical endpoint | not classified | unknown |
| Telomere length | declined | no canonical endpoint | not classified | unknown |
| Cholesterol | declined | no canonical endpoint | not classified | unknown |
| Growth-differentiating factor-15 (GDF-15) | endorsed | no canonical endpoint | not classified | unknown |
| Insulin-like growth factor 1 (IGF-1) | endorsed | no canonical endpoint | not classified | unknown |
| Regulator-mapped, never evaluated for aging25 rulers | ||||
| Quality of life | not evaluated | patient-reported | 142 | unknown |
| Mood / anxiety scales | not evaluated | patient-reported | 131 | unknown |
| Adherence / retention | not evaluated | safety, no efficacy claim | 101 | unknown |
| Adverse events / tolerability | not evaluated | safety, no efficacy claim | 84 | unknown |
| Body weight / BMI | not evaluated | no standing | 47 | unknown |
| All-cause mortality / survival | not evaluated | the outcome itself | 32 | unknown |
| Heart rate | not evaluated | FDA surrogate validated for Supraventricular tachycardia | 26 | unknown |
| Incident clinical event | not evaluated | the outcome itself | 22 | unknown |
| Pharmacokinetics (Cmax / AUC / concentration) | not evaluated | exposure, no efficacy claim | 20 | unknown |
| Progression-free survival (PFS) | not evaluated | FDA surrogate validated for Metastatic solid tumors (multiple oncology indications) | 14 | unknown |
| Serum triglycerides | not evaluated | FDA surrogate validated for Hypertriglyceridemia | 11 | unknown |
| Insulin sensitivity / fasting insulin | not evaluated | no standing | 9 | unknown |
| LDL cholesterol | not evaluated | FDA surrogate validated for Hypercholesterolemia | 8 | unknown |
| Maximum tolerated dose (MTD) | not evaluated | safety, no efficacy claim | 8 | unknown |
| Bone mineral density | not evaluated | FDA surrogate validated for Osteoporosis | 7 | unknown |
| Senescent cell burden (p16INK4a) | not evaluated | no standing | 7 | unknown |
| NAD+ / NADH concentration | not evaluated | no standing | 5 | unknown |
| Overall response rate (ORR) | not evaluated | FDA surrogate validated for steroid-refractory acute graft versus host disease (SR-aGvHD) | 5 | unknown |
| Autophagy / mitophagy flux | not evaluated | no standing | 4 | unknown |
| Serum uric acid | not evaluated | FDA surrogate validated for Gout, Supportive cancer care | 3 | unknown |
| Event-free survival (EFS) | not evaluated | FDA surrogate validated for Cancer: hematological malignancies | 2 | unknown |
| eGFR / serum creatinine | not evaluated | FDA surrogate validated for Chronic kidney disease | 2 | unknown |
| Fatigability / physical fatigue scale | not evaluated | patient-reported | 1 | unknown |
| Haematologic response | not evaluated | FDA surrogate validated for Cancer: hematological malignancies | 0 | unknown |
| Major molecular response (MMR) | not evaluated | FDA surrogate validated for Cancer: hematological malignancies | 0 | unknown |
endorsed reached 70% panel agreementdeclined evaluated and did not reach itnot evaluated the panel never considered itnot classified no canonical endpoint, so not countableunknown no published within-person reliability
What the trials measure
Share of 2,715 aging-relevant interventional trials whose registered outcome measures name each endpoint class. Counted on the outcome measures only: widening the search to conditions would catch trials that recruit frail patients, which is a population, not an endpoint. Classes overlap, so these do not sum.
| Endpoint class | Trials | Share |
|---|---|---|
| Physical and cognitive function | 302 | 11.1% |
| Frailty index | 66 | 2.4% |
| Epigenetic / biological age | 30 | 1.1% |
| Senescence markers | 15 | 0.6% |