Associations between elevated kidney and liver biomarker ratios, metabolic syndrome and all-cause and coronary heart disease (CHD) mortality: analysis of the U.S. National Health and Nutrition Examination Survey (NHANES)

BACKGROUND: We examined the relationship between ratios of select biomarkers of kidney and liver function on all-cause and coronary heart disease (CHD) mortality, both in isolation, and in combination with metabolic syndrome (MetS), among adults (20 + years, n = 10,604). METHODS: Data was derived from the U.S. National Health and Nutrition Examination Survey (1999–2016) including public-use linked mortality follow-up files through December 31, 2015. RESULTS: Select biomarker ratios of kidney (UACR or albuminuria and BUN-CR) and liver (AST-ALT and GGT-ALP) function in isolation and in combination with MetS were associated with all-cause and CHD mortality. Compared to individuals with neither elevated biomarker ratios nor MetS (HR = 1.00, referent), increased risk of all-cause mortality was observed in the following groups: MetS with elevated UACR (HR, 95% CI = 2.57, 1.99–3.33), MetS with elevated AST-ALT (HR = 2.22, 1.61–3.07), elevated UACR without MetS (HR = 2.12, 1.65–2.72), and elevated AST-ALT without MetS (HR = 1.71, 1.35–2.18); no other biomarker ratios were associated with all-cause mortality. For cause-specific deaths, elevated risk of CHD mortality was associated with MetS with elevated UACR (HR = 1.67, 1.05–2.67), MetS with elevated AST-ALT (HR = 2.80, 1.62–4.86), and elevated BUN-CR without MetS (HR = 2.12, 1.12–4.04); no other biomarker ratios were associated with CHD mortality. CONCLUSION: Future longitudinal studies are necessary to examine the utility of these biomarker ratios in risk stratification for chronic disease management. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12872-021-02160-w.