Low Fischer’s Ratio Associated with Increased Mortality in Chronic Kidney Disease: Study
Sweden: Researchers have found in a new study that a lower Fischer’s ratio—a marker reflecting the balance between branched-chain and aromatic amino acids—is linked to a higher risk of death among patients with kidney failure, particularly those with underlying cardiovascular disease.
A study published in Scientific Reports by Qianying Zhang and colleagues from Karolinska Institutet, Sweden, sheds light on the prognostic significance of metabolic alterations in individuals initiating dialysis. The findings suggest that disruptions in amino acid balance may serve as an important indicator of survival outcomes in this vulnerable population.
Fischer’s ratio (FR), calculated as the ratio of branched-chain amino acids (BCAAs)—valine, isoleucine, and leucine—to aromatic amino acids (AAAs)—phenylalanine and tyrosine—has been previously associated with metabolic health. In kidney failure, metabolic disturbances are common, and the researchers aimed to explore whether FR could predict mortality risk.
For this purpose, the researchers analyzed 328 patients with kidney failure who had recently started dialysis. The median age of participants was 54 years, and 60% were men. Plasma concentrations of amino acids were measured using high-performance liquid chromatography (HPLC). The study employed competing-risk regression models, accounting for renal transplantation as a competing event, to assess survival over five years. Additionally, advanced statistical models were used to evaluate continuous relationships between amino acid levels and mortality.
The study led to the following findings:
- The median follow-up duration was approximately 29 months, during which over half of the patients underwent kidney transplantation and about one-quarter died.
- Patients with lower Fischer’s ratio (FR), including those in the middle and lowest tertiles, had a significantly higher risk of mortality compared to those with higher FR levels.
- The risk of death was approximately 74% higher among individuals with reduced FR.
- Lower FR was associated with increased levels of inflammation.
- Reduced FR was also linked to protein-energy wasting, a condition known to adversely affect outcomes in chronic kidney disease.
- These associations indicate that FR may reflect underlying metabolic and nutritional disturbances contributing to disease progression.
- The relationship between low FR and mortality was particularly pronounced in patients with pre-existing cardiovascular disease.
- In this subgroup, patients with lower FR had more than a fourfold increased risk of death.
- The findings suggest a potential interaction between metabolic imbalance and cardiovascular disease in influencing survival outcomes.
Overall, the findings indicate that Fischer’s ratio could serve as a useful biomarker for risk stratification in patients with kidney failure. Monitoring amino acid profiles may help clinicians identify high-risk individuals and guide targeted interventions. The authors emphasize that further research is needed to determine whether modifying amino acid balance could improve survival in this population.
Reference:
Zhang, Q., Suliman, M. E., Qureshi, A. R., Guo, F., Troise, D., Xu, R., Bárány, P., Heimbürger, O., Stenvinkel, P., & Lindholm, B. (2026). Low Fischer’s ratio is associated with increased mortality in patients with kidney failure. Scientific Reports. https://doi.org/10.1038/s41598-026-46326-y
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