Background: Neutrophil-to-lymphocyte ratio (NLR) has been widely evaluated as a biomarker in various medical and surgical prognoses, but its usefulness in diabetic kidney disease is not yet known.
Methods: This prospective observational study included outpatients, comprised of 190 men aged 73 ± 11 (mean ± standard deviation) years and 175 women aged 77 ± 10 years at baseline, from a rural hospital. We examined the relationship between baseline NLR calculated by analyzing the differential leukocyte counts in the complete blood count and the 1.5-year estimated glomerular filtration rate (eGFR) decline rate (i.e. 1.5-year eGFR − baseline eGFR) *100/baseline eGFR. Rapid eGFR decline rate was defined as a value <-15%.
Results: Multiple linear regression analysis using rapid eGFR decline rates as objective variables, adjusted for confounding factors as explanatory variables, showed that tertiles of NLR (β=0.120, p=0.018) as well as hemoglobinA1c, presence of antidiabetic medication, and urinary albumin excretion were significantly and independently associated with a rapid eGFR decline rate. The multivariate-adjusted odds ratios (95% confidence interval) of the 2nd and 3rd tertiles of baseline NLR for rapid eGFR decline rate were 3.94 (1.34-11.6) and 3.93 (1.26-12.3), respectively. Multivariate-adjusted mean eGFR (95% confidence interval) values after 1.5 years categorized by tertile of baseline NLR were: 1st, 64.2 (62.1-66.3); 2nd, 60.5 (58.5-62.6); and 3rd, 59.1 (57.0-61.2).
Conclusions: These results suggest that baseline NLR might be a useful biomarker for renal function decline in diabetic outpatients.