Methodology

Last reviewed: August 2026

Scope

This review covers 28 tests and test categories commonly included in "longevity", "executive health", or "biological age" testing packages marketed to healthy, asymptomatic adults: 18 blood-based markers, 6 imaging/scan modalities, and 4 emerging/consumer categories (genetic testing, gut microbiome sequencing, epigenetic clocks, and bundled panels). It does not cover disease-specific screening already well-codified elsewhere (e.g. cancer screening schedules, prenatal screening) except where those tests overlap with the longevity-testing menu (e.g. DEXA bone density).

The grading rubric

Each test receives one grade reflecting its evidence base for the use case actually being sold — i.e. testing/screening an asymptomatic or average-risk adult for longevity/risk-stratification purposes, not for diagnosing a symptomatic patient (which is often better-evidenced and out of scope here).

Grade	Definition
Strong	Multiple randomised controlled trials and/or large, consistent prospective cohorts and meta-analyses demonstrate association with hard clinical outcomes (mortality, MI, stroke, fracture), and major guideline bodies (e.g. USPSTF, ACC/AHA, ESC/EAS, KDIGO) endorse use in a defined population. Acting on an abnormal result has a demonstrated path to changed management and improved outcomes.
Moderate	Consistent observational and/or genetic (Mendelian randomisation) evidence links the marker to hard outcomes, with a plausible causal mechanism, and guideline bodies support selective or risk-stratified use — but a dedicated RCT showing that testing (and acting on the result) improves outcomes is limited, mixed, or not yet population-general.
Weak	Evidence is associative/cross-sectional only, guideline bodies explicitly do not recommend routine use in asymptomatic adults, or randomised trial data are neutral/negative despite biological plausibility (a classic case of a "confounded" biomarker).
Emerging	Biologically plausible and an active area of research, but longitudinal human outcome data are too immature to grade for clinical use. Commercial availability has outpaced the evidence base. Not recommended as a basis for individual decisions at this time.

Sourcing standard

Every factual claim about a study's findings is backed by a real, checkable citation — author(s), journal, year, and a link to PubMed or the publisher where available.
Where we could not verify a specific claim against a real, retrievable publication, we say so explicitly in the text rather than presenting an unsupported number.
We preferentially cite landmark RCTs, large prospective cohorts, and consensus/guideline statements (USPSTF, ACC/AHA, ESC/EAS, Endocrine Society, KDIGO) over single small studies or press releases.
Cost figures (SGD) are indicative ranges based on typical private-sector pricing in Singapore as of 2026 and will vary by provider, panel bundling, and whether a doctor's consultation is included. They are not sourced from a specific price list and should be confirmed directly with a lab or clinic.

Key citations (19 landmark studies)

Every PMID cited anywhere on this site — in the evidence cards on Blood Panels, Scans, and Emerging & Overhyped, and in the long-tail cost articles — is indexed here in one place, grouped by category. This lets a reader (or a clinician colleague) sanity-check the evidence base in one pass instead of hunting across pages.

Test	Citation	PMID	Key finding
Blood panels
ApoB	Sniderman AD, et al. JAMA Cardiol. 2019.	31642874	ApoB outperforms LDL-C for cardiovascular risk prediction, especially at discordant lipid values.
Lp(a)	Kamstrup PR, et al. JAMA. 2009.	19509380	Elevated Lp(a) independently predicts myocardial infarction risk in the general population.
HOMA-IR	Matthews DR, et al. Diabetologia. 1985.	3899825	Original derivation of the HOMA-IR model from fasting glucose and insulin.
hs-CRP	Ridker PM, et al. N Engl J Med. 2008 (JUPITER).	18997196	Statin therapy reduced events in patients with elevated hs-CRP but normal LDL-C — the trial hs-CRP's "Moderate" grade rests on.
Vitamin D	Manson JE, et al. N Engl J Med. 2019 (VITAL).	30415629	25,871 adults randomised to vitamin D3 2000IU/day vs. placebo: no significant reduction in cancer incidence or major CV events over 5 years.
Vitamin D	USPSTF Recommendation Statement. JAMA. 2021.	33847711	Evidence insufficient to assess benefit/harm of screening asymptomatic adults for vitamin D deficiency (Grade I).
Vitamin D	USPSTF Recommendation Statement. Ann Intern Med. 2014.	25419853	Same "insufficient evidence" verdict as the 2021 update, reached independently 7 years earlier.
Testosterone	Lincoff AM, et al. N Engl J Med. 2023 (TRAVERSE).	37326322	Cardiovascular safety of testosterone replacement in men with hypogonadism and pre-existing CV risk — the largest RCT of its kind.
Thyroid (TSH)	US Preventive Services Task Force. Ann Intern Med. 2004.	14734336	Insufficient evidence to recommend routine thyroid screening in asymptomatic, non-pregnant adults.
Ferritin / haemochromatosis	USPSTF Recommendation Statement. Ann Intern Med. 2006.	16880462	Recommends against routine genetic screening for hereditary haemochromatosis in asymptomatic adults (Grade D). Note: USPSTF marked this topic "inactive" in 2018 — not superseded by a contradicting statement, simply not re-reviewed since.
Omega-3 index	Harris WS, von Schacky C. Prev Med. 2004.	15208005	Proposes the omega-3 index itself as a candidate cardiovascular risk marker.
Homocysteine	Lonn E, et al. N Engl J Med. 2006.	16531613	B-vitamin therapy lowered homocysteine but did not reduce cardiovascular events — the classic "confounded biomarker" case.
Scans
CAC score	Detrano R, et al. N Engl J Med. 2008 (MESA).	18367736	Coronary artery calcium score predicts coronary events across multiple ethnic groups, independent of traditional risk factors.
DEXA (body composition)	Kuk JL, et al. "Visceral fat is an independent predictor of all-cause mortality in men."	16571861	Visceral fat, measurable via DEXA, independently predicts all-cause mortality.
Carotid ultrasound	USPSTF Recommendation Statement. JAMA. 2021.	34058106	Recommends against screening asymptomatic adults for carotid artery stenosis.
Emerging & overhyped
APOE genotyping	Mayeux R, et al. N Engl J Med. 1998.	9468467	APOE genotype's predictive value for Alzheimer's risk is population-level, not reliable for individual prognosis.
Gut microbiome testing	Porcari S, et al. (international consensus statement). Lancet Gastroenterol Hepatol. 2024.	39647502	Expert panel concludes evidence for clinical utility of commercial microbiome testing remains scarce; calls for standardised reporting.
Epigenetic clocks	"From population science to the clinic? Limits of epigenetic clocks as personal biomarkers." Epigenomics. 2025.	41403206	Technical and biological limitations mean epigenetic clocks are not yet fit for individual-level clinical decisions, even though they work at a population level.
Bundled/package panels	Krogsbøll LT, et al. Cochrane Database Syst Rev. 2019.	30699470	15 RCTs, 250,000+ participants: general health checks in adults do not reduce all-cause, cardiovascular, or cancer mortality.

This list covers the study or guideline statement anchoring each test's grade, not every source consulted — several test cards cite the same landmark study (e.g. the CAC and DEXA PMIDs each appear on two pages: their own evidence card and the matching long-tail article). Counted once per unique PMID, 19 distinct studies/statements are cited live across the site as of August 2026.

Limitations of this review

This is a narrative evidence review conducted by one author with AI assistance, not a formally registered systematic review (no PROSPERO registration, no dual independent screening, no formal risk-of-bias scoring per study). Grades reflect a structured but qualitative synthesis of major trials, cohorts, and guideline positions per test — treat them as a starting point for discussion with a clinician, not as a substitute for a full guideline panel's work.
Evidence changes. A grade here reflects the literature as reviewed in August 2026; several areas (Lp(a)-lowering therapies, epigenetic clock validation, GLP-1-era metabolic risk markers) are moving quickly and may re-grade within a year or two.
Grades are population-level judgements. An individual patient's history, symptoms, and family history can make a "Weak" test appropriate for them specifically — that determination requires a clinician, not this website.

Independence

No laboratory, clinic, or supplement company had input into, or paid for, any grade on this site. Where the site carries advertising or affiliate links (see the Privacy & Cookie Policy), those relationships are disclosed and do not alter grading.