Blood-derived metabolic and inflammatory indices flag risk in cardiovascular-kidney-metabolic syndrome, but remain research tools

In 2023, the American Heart Association introduced the term cardiovascular–kidney–metabolic syndrome, or CKM syndrome, to capture the intertwined biology of heart disease, kidney dysfunction and metabolic disorders. A newly published narrative review in Cardiovascular Diabetology now takes stock of a fast-growing family of cheap, blood-test-derived indices that researchers have proposed as risk markers in this population, and its verdict is deliberately cautious: the indices consistently point in expected directions, but none is ready to guide patient care.

The review, led by authors including Liyan Chen and Weixiang Luo, synthesizes evidence drawn from several large public databases, predominantly the National Health and Nutrition Examination Survey (NHANES), the UK Biobank and the China Health and Retirement Longitudinal Study (CHARLS), with additional evidence from MIMIC-IV, hospital-based cohorts and other multicohort datasets. The authors performed a structured search of PubMed, Web of Science, the Cochrane Library, Embase and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) from database inception to September 8, 2026, and included cohort studies reporting associations between specified indices and outcomes in CKM populations.

Because the underlying studies differ so widely in CKM staging, exposure scaling and outcome definitions, the team chose a structured narrative synthesis rather than a meta-analysis, and hazard ratios were not compared across indices. That methodological restraint matters: pooling heterogeneous effect estimates could manufacture a false impression of precision where the real message is directional consistency, not numerical comparability.

Seven index families were examined. The first is the triglyceride–glucose (TyG) index and its derivatives, a simple logarithmic combination of fasting triglycerides and glucose that serves as a surrogate for insulin resistance. The second is the estimated glucose disposal rate (eGDR), which estimates whole-body insulin sensitivity from clinical variables. The third is the C-reactive protein–triglyceride–glucose index (CTI), which blends an inflammatory marker with the metabolic TyG core. The fourth comprises the systemic immune-inflammation index (SII) and the systemic inflammation response index (SIRI), both built from routine white blood cell differentials.

The remaining families include the oxidative balance score (OBS), which aggregates dietary and lifestyle pro- and antioxidant exposures; the atherogenic index of plasma (AIP) and its adiposity-adjusted derivatives, which reflect the cholesterol content of triglyceride-rich lipoproteins; the stress hyperglycaemia ratio (SHR), which relates admission glucose to estimated average glucose; and a set of exploratory indices, among them the remnant cholesterol inflammatory index (RCII), the C-reactive protein-albumin-lymphocyte (CALLY) index and its modified version (m-CALLY), and the red blood cell distribution width-to-albumin ratio (RAR).

The headline pattern is strikingly uniform. Across CKM stages 0–3, higher levels of most of these indices were associated with a higher risk of cardiovascular events and all-cause mortality, whereas higher eGDR and higher OBS were associated with a lower risk. In other words, indices that proxy insulin resistance, systemic inflammation, atherogenic lipoproteins, stress hyperglycaemia or red cell turnover tend to travel with worse outcomes, while indices that proxy better insulin sensitivity and a more favourable oxidative balance travel with better ones.

Yet the review’s central caution is that directional consistency is not clinical validity. Head-to-head comparisons between indices are lacking, validated cut-off values are unavailable, and incremental predictive value beyond established risk models is inconsistently reported across the cohort literature. Without those three ingredients, a clinician cannot know whether one index outperforms another, where a meaningful threshold lies, or whether the index adds anything to tools already in use.

The evidence gap extends to treatment. No randomized trial has tested whether index-guided management improves outcomes, meaning there is currently no proof that acting on these numbers changes a patient’s trajectory. The authors therefore conclude that these measures should be considered hypothesis-generating research tools rather than guideline-ready clinical instruments, a framing that resists the temptation to translate cheap arithmetic into bedside decisions prematurely.

The review’s research insights section reinforces that position. Individual cohort studies do link novel metabolic indices to adverse outcomes in CKM, but the evidence is heterogeneous in CKM staging, exposure scaling and outcome definitions, and direct head-to-head comparisons and validated cut-off values are largely lacking. The indices are inexpensive and routinely available, and they may help identify high-risk individuals in research settings, but prospective validation, head-to-head comparisons and intervention trials are needed before clinical translation.

For readers following the CKM field, the practical takeaway is measured. These indices distil routine blood panels into single numbers that track cardiometabolic and inflammatory burden, and across large cohorts from the United States, the United Kingdom and China they align with hard outcomes in the expected directions. But until studies demonstrate that they add predictive value beyond established models and that management guided by them improves health, their place remains in the research literature, not the clinic.

Subject of Research: Associations of emerging metabolic and inflammatory blood indices with cardiovascular events and all-cause mortality in cardiovascular-kidney-metabolic syndrome

Article Title: Associations between emerging metabolic and inflammatory indices and cardiovascular events and all-cause mortality in patients with cardiovascular-kidney-metabolic syndrome: a narrative review

Article References: Chen, L., Wen, X., Guo, H., Mo, Y., Luo, H., Lyu, Y., Wang, J., & Luo, W. (2026). Associations between emerging metabolic and inflammatory indices and cardiovascular events and all-cause mortality in patients with cardiovascular-kidney-metabolic syndrome: a narrative review. Cardiovascular Diabetology. https://doi.org/10.1186/s12933-026-03404-9

Image Credits: AI Generated

DOI: 10.1186/s12933-026-03404-9

Keywords: cardiovascular-kidney-metabolic syndrome, TyG index, estimated glucose disposal rate, C-reactive protein-triglyceride-glucose index, systemic immune-inflammation index, oxidative balance score, atherogenic index of plasma, stress hyperglycaemia ratio, NHANES, UK Biobank, CHARLS, narrative review