1. Acute ischemic stroke prognosis
2. BUN levels stroke recovery
3. Stroke outcome research
4. Nonlinear association BUN stroke
5.Nonlinear association BUN stroke

A recent study published in ‘Clinical Nutrition ESPEN’ journal presents enlightening findings on the association of blood urea nitrogen (BUN) levels with the outcomes of acute ischemic stroke (AIS) patients after three months, unveiling a nonlinear relationship between the two. This article reports on the study’s methodology, findings, implications for clinical practice, and sets forth a discussion in the broader context of stroke management. The original study, a second analysis predicated on a prospective cohort study, underscores the necessity for nuanced understanding of metabolic indicators in the prognosis of AIS. The authors hailed from the Department of Emergency Medicine and the Department of Nephrology at the Shenzhen Second People’s Hospital.


Stroke remains a leading cause of mortality and long-term disability worldwide, with acute ischemic stroke (AIS) accounting for approximately 87% of all stroke cases. The prognostication and management of AIS pose significant clinical challenges, demanding the identification of reliable biomarkers that can predict patient outcomes. The study, as published in the February 2024 edition of ‘Clinical Nutrition ESPEN’, proffers fresh insights into how blood urea nitrogen (BUN) levels correlate with AIS patient outcomes at the 3-month post-stroke interval, marking an advance in stroke outcome research.

Study Overview

This retrospective study scrutinized data from 1,866 AIS patients who were admitted to a hospital in South Korea from January 2010 to December 2016. Spearheaded by Zhou Pan and colleagues, the study hinged on an assortment of analytical techniques, including binary logistic regression and smooth curve fitting, to parse the connection between BUN levels and 3-month poor outcomes following an ischemic stroke. The authors adjusted for multiple covariates to mitigate confounding effects.


Significantly, the study disclosed a nonlinear association between BUN levels and patient outcomes after an AIS. An inflection point was discovered at a BUN level of 13 mg/dl. Below this threshold, each unit increment in BUN was linked to a 14.1% reduction in the odds of a poor outcome at the three-month mark (OR = 0.859, 95% CI: 0.780-0.945, p = 0.0019), signaling that moderate levels of BUN might be protective to some extent. Conversely, beyond the 13 mg/dl inflection point, the relationship was determined to be statistically insignificant, indicative of a plateau effect in the protective nature of BUN.

Implications for Clinical Practice

The study’s results intimate that within a specific range, maintaining BUN levels may be conducive to enhanced outcomes for patients recovering from an AIS. However, it is incumbent upon clinicians to acknowledge the inflection point and appreciate that the relationship does not hold beyond the 13 mg/dl mark. Interpreted judiciously, this could inform clinical decisions, particularly in the administration of nutritional support and other interventions that might influence BUN levels.

Further Discussions and Recommendations

The finding of a nonlinear relationship between BUN and stroke outcomes is revelatory, urging a re-examination of current protocols that perhaps overlook the nuanced roles of metabolic factors in stroke prognosis. The saturation effect identified in this study further cautions against a one-size-fits-all approach, suggesting a more granulated patient management strategy based on individual BUN levels.

The researchers advocate for future studies to elucidate the mechanisms driving the relationship between BUN and AIS outcomes, and to corroborate their findings in more diverse patient populations. The potential influence of renal function, dietary protein intake, and catabolic states on BUN levels and stroke recovery should also be of interest in subsequent research endeavors.

Study Limitations and Conclusion

As with any retrospective analysis, the study has limitations, including the potential for residual confounding and the inability to establish causality. Moreover, the cohort was from a single center which may affect the generalizability of the results.

Nonetheless, Zhou Pan and collaborators have posited a compelling exposition of the nonlinearity in the relationship between BUN levels and 3-month AIS outcomes, filling a lacuna in the burgeoning corpus of stroke outcome prognosticators. This study is a valuable addition to the clinical literature, providing a fresh perspective on the prognostic value of metabolic indicators in stroke recovery.

The study “Blood urea nitrogen has a nonlinear association with 3-month outcomes with acute ischemic stroke: A second analysis based on a prospective cohort study” is available in the February 2024 issue of ‘Clinical Nutrition ESPEN’, and the DOI for this work is 10.1016/j.clnesp.2023.12.001.


1. Zhou Pan, Liu Ren-Li, Wang Fang-Xi, Hu Hao-Fei, Deng Zhe. (2024). Blood urea nitrogen has a nonlinear association with 3-month outcomes with acute ischemic stroke: A second analysis based on a prospective cohort study. Clinical Nutrition ESPEN, 59, 140-148.
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5. Smith, E. E., et al. (2013). Guidelines for the prevention of stroke in patients with stroke and transient ischemic attack: A guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke, 44(7), 2160-2236.