Blood Urea Nitrogen-to-Serum Albumin Ratio for Prognosis in T2D With CKD

Chronic kidney disease (CKD) is common among critically ill patients with type 2 diabetes mellitus (T2D). Shizhen Liu and other researchers explored the relationship between blood urea nitrogen-to-serum albumin ratio (BAR) and mortality in patients with T2D and CKD in an intensive care unit (ICU). Their findings appeared in Scientific Reports.

Research has found that BAR can be a useful biomarker for poor prognosis of many diseases, including acute kidney injury, but its impact in patients with T2D and CKD has not been examined. To better understand how BAR impacts mortality in T2D with CKD, the researchers retrospectively recruited patients from the Medical Information Mart database. The database contains clinical information from 2001 to 2012 on more than 50,000 ICU patients at the Beth Israel Deaconess Medical Center in Boston, Massachusetts.

A total of 1920 patients were enrolled in the study. Participants were divided into three groups: low-BAR (BAR <9.2; n=486), mid-BAR (BAR 9.2-21.3; n=954), and high-BAR (BAR >21.3; n=480). There were 197 (40.5%), 508 (53.2%), and 284 (59.2%) males in each group, respectively. Mean age was 79 for the low-BAR group, 75 for mid-BAR, and 72 for high-BAR.

The researchers extracted the following variables: age, gender, weight, systolic blood pressure (SBP), diastolic blood pressure (DBP), coronary artery disease (CAD), chronic heart failure (CHF), hypertension, CKD stage, sequential organ failure assessment (SOFA), hemoglobin (HGB), white blood cell (WBC) count, platelet count, potassium, sodium, phosphate, creatinine, blood urea nitrogen (BUN), albumin (ALB), alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate transaminase (AST), glucose, lactate level, arterial oxygen partial pressure (PaO₂), partial thromboplastin time (PTT), prognostic nutritional index (PNI), and estimated glomerular filtration rate (eGFR). They calculated BAR by dividing BUN by ALB level.

Outcomes included 90-day mortality, length of ICU stay, hospital mortality, and 30-day mortality. The researchers performed Cox regression model and Kaplan-Meier survival curve analyses to study the association between BAR and 90-day mortality. They conducted subgroup analysis to verify the consistency of the association.

The high-BAR group had significantly longer length of ICU stay, 30-day mortality, and 90-day mortality (P<.05). Cox regression analysis showed that high BAR level was significantly associated with an increased risk of 90-day mortality in three different models. Model 1 was unadjusted; model 2 adjusted for age, gender, weight, SBP, DBP, CAD, CHF, hypertension, CKD stage, and SOFA score; model 3, in addition to the adjustments made in model 2, adjusted for HGB, WBC count, platelet count, potassium, sodium, phosphate, ALP, ALT, AST, glucose, PaO₂, PTT, and eGFR. The adjusted hazard ratios for models 1, 2, and 3 were 1.768 (1.409-2.218), 1.934 (1.489-2.511), and 1.864 (1.399-2.487), respectively (95% CI; P<.05).

Subgroup analysis confirmed the consistency of results. In addition, Kaplan-Meier survival curve analysis found that the high-BAR group had a lower 90-day survival rate. The results imply that BAR could be a simple, useful prognostic tool in T2D patients with CKD in an ICU.

The authors acknowledged several limitations. The study’s single-center, retrospective design resulted in selection bias. Data were old, and some unrecorded clinical information was missing. Only BUN and ALB records from patients’ first admission were included, making the prognostic impact of dynamic changes in BAR unclear. Lastly, the underlying mechanism of how BAR affects prognosis could not be established.

In summary, the authors wrote, “A higher BAR was significantly associated with an increased risk of 90-day mortality. BAR could [serve] as a prognostic predictor for 90-day mortality in [T2D] patients with CKD in ICU, due to its inexpensive and readily available nature.”

Source: Scientific Reports