Blood urea nitrogen is independently associated with renal outcomes in Japanese patients with stage 3–5 chronic kidney disease: a prospective observational study

Abstract Background Blood urea nitrogen (BUN) is one of the substances that affects the calculated serum osmolality (cSosm). A previous study demonstrated that BUN and cSosm were independently associated with the development of chronic kidney disease (CKD) in patients with preserved kidney function. In advanced CKD stages, there is a concomitant increase in cSosm and BUN levels. However, it remains unclear whether BUN or cSosm levels are related to renal outcomes in patients with moderate to severe kidney dysfunction. The aim of this study was to clarify whether the BUN or cSosm level is associated with kidney disease progression in patients with advanced CKD. Methods In this prospective study, we enrolled 459 patients with CKD (stages 3–5). The composite renal endpoint was end-stage renal disease (ESRD) or death, and ESRD alone was added as an alternative outcome. A Cox proportional hazards model was utilized to determine the risk factors for a poor renal outcome. We adjusted for covariates including estimated glomerular filtration rate (eGFR). The cSosm (mOsm/kg) was calculated using the following formula: (2 × sodium) + (BUN/2.8) + (glucose/18). Results During a median follow-up of 25.8 months, the renal endpoint was observed in 210 patients. Multivariable Cox analysis determined the hazard ratio (HR) [95% confidence interval (CI)] for the composite renal outcome in the second, third, and fourth BUN quartiles were 1.36 (0.72–2.58), 1.87 (0.95–3.66), and 2.66 (1.23–5.76) (P for trend < 0.01), respectively compared with the first BUN quartile. Conversely, by multivariable Cox analysis, the HRs (95% CIs) for poor outcomes in the second, third, and fourth cSosm quartiles, compared with the first cSosm quartile, were 1.13 (0.69–1.87), 0.95 (0.58–1.55), and 1.26 (0.78–2.03), respectively (P for trend = 0.39). In addition, with regard to the renal outcome of ESRD alone, higher BUN quartiles had a significantly increased risk for the outcome, but cSosm levels were not associated with the outcome. Conclusions Higher BUN levels, but not cSosm levels, were associated with adverse renal outcomes independent of the eGFR, suggesting that BUN may be a useful marker for predicting kidney disease progression

High neutrophil/lymphocyte ratio is associated with poor renal outcomes in Japanese patients with chronic kidney disease

Background: Several studies have shown that the neutrophil/lymphocyte ratio (NLR) is a marker that reflects the state of systemic inflammation. A high NLR was reported to be associated with cardiovascular events and mortality. However, little is known about the association between NLR and kidney disease progression in patients with chronic kidney disease (CKD). Therefore, the aim of the present study was to determine whether NLR is associated with renal outcomes in CKD patients. Methods: This prospective observational study included 350 consecutive patients with stage 1–4 CKD treated between June 2009 and November 2016. Data were collected until June 2017. The endpoint was the composite of end-stage renal disease requiring dialysis or death. Subjects were divided into two groups according to high and low NLR levels. A Cox proportional hazards model was used to determine the risk factors for composite outcomes. Results: The composite endpoint was observed in 83 patients during the median follow-up period of 31.8 months: 29 in the low NLR group and 54 in the high NLR group. Multivariable analysis showed that the high NLR group had a significant increase in the hazard ratio (HR) for composite outcomes (HR 1.67, 95% confidence interval 1.02–2.77) compared with the low NLR group. Conclusion: The present study demonstrated that a high NLR was associated with poor renal outcomes, suggesting that NLR may be a useful marker for prognostic prediction in patients with CKD