Urea-to-creatinine ratio as a biomarker for clinical outcome and response to nutritional support in non-critically ill patients: A secondary analysis of a randomized controlled trial

Background: Assessing a patient's catabolism in clinical practice is challenging but could help guide nutritional interventions. The urea-to-creatinine ratio (UCR) reflects muscle breakdown and protein metabolism and has been associated with risk for overfeeding and adverse outcomes in the critical care setting. We validated this concept in a well-characterized population of medical ward patients from a previous nutritional trial. Methods: This secondary analysis of the Effect of Early Nutritional Support on Frailty, Functional Outcomes, and Recovery of Malnourished Medical Inpatients Trial (EFFORT) examined baseline UCR and changes during follow-up in medical inpatients at risk for malnutrition. A catabolic state was defined as a high baseline UCR or an increase in UCR over 7 days. The primary endpoint was mortality at 30 days. Results: We included 1595 of 2028 EFFORT patients with baseline UCR measurements and 870 who also had UCR measurements on day 7. A high baseline UCR, as well as an increase in UCR over 7 days, were associated with increased mortality (adjusted HR for 30-day mortality 2.05 (1.47–2.87) p < 0.001 and 2.02 (1.34–3.06) p = 0.001). There was no difference in treatment response when stratifying patients based on baseline or follow-up UCR. Conclusion: Assessment of catabolism through UCR measurement at baseline and changes during follow-up was associated with increased mortality and adverse outcomes in medical inpatients at nutritional risk. However, this stratification was not associated with response to nutritional therapy in our sample. Further studies into the dynamic changes in UCR are needed to better understand the clinical implications for medical ward patients. Clinical Trial Registration: Clinicaltrials.gov