Biological basis of lymphocyte ratios for survival prediction in hemodialysis patients: a longitudinal study.

Purpose: The neutrophil-to-lymphocyte (NLR) and platelet-to-lymphocyte (PLR) ratios have been proposed as emerging markers of inflammation and prognosis in maintenance hemodialysis (MHD) patients. However, to date, no longitudinal performance of these indices is known. The study's purpose was to examine the longitudinal relationship between NLR, PLR, inflammatory and nutritional parameters in MHD patients and how their changes over time associate with adverse clinical outcomes.

Methods: A historical longitudinal cohort study was conducted using a clinical database which included 554 patients (mean age, 67.6 ± 14.2 years; 34% women) from a single center receiving MHD from November 2007 to July 2018. NLR, PLR, C-reactive protein (CRP) and nutritional parameters were recorded at 0, 6, 12, 18, 24, 30 and 36 months, followed by 58 additional months of clinical observations.

Results: In a linear mixed-effects model adjusted for baseline demographics and clinical parameters, including white blood cell count, NLR and PLR were both associated with CRP levels at any given time point observation (linear estimates (95% CI): 1.53, (0.11-2.95) and 1.55 (0.15-2.93), respectively). For each 1.0-unit increase in NLR over time, the fully adjusted all-cause mortality hazard ratio using Cox models with the time-varying risk effect was 1.04 (95% CI 1.01-1.07, P = 0.006). However, when CRP was included in this model, the relationship was no longer significant. PLR's performance did not match the prognostic marker.

Conclusion: Longitudinal changes in NLR mimic CRP changes and predict all-cause mortality risk in MHD patients.