Mean Platelet Volume and Mean Platelet Volume-to-Platelet Ratio and Their Association With Mortality in Patients Undergoing Maintenance Hemodialysis.

Introduction Patients receiving maintenance hemodialysis (HD) remain at high risk of cardiovascular morbidity and mortality despite advances in dialysis therapy. The mean platelet volume (MPV) reflects platelet activation and has emerged as a potential prognostic biomarker, while the mean platelet volume-to-platelet ratio (MPR) may provide additional information regarding thrombo-inflammatory status. This study evaluated the associations of MPV and MPR with long-term survival, cardiovascular mortality, dialysis adequacy, and anemia-related parameters in maintenance HD patients. Materials and methods This retrospective single-center observational study included 98 adult patients undergoing maintenance HD at the Department of Nephrology and Dialysis, University Hospital "St. Marina", Varna, Bulgaria. Patients were stratified according to baseline MPV into three groups: <10.0 fL (n=38), 10.0-11.0 fL (n=32), and >11.0 fL (n=28). Clinical, laboratory, and dialysis-related parameters were analyzed using annual mean values. Long-term survival was analyzed using Kaplan-Meier estimates, and survival distributions were compared with the log-rank test. The associations of MPV and MPR with all-cause mortality were subsequently examined using univariable Cox proportional hazards regression, with effect estimates reported as hazard ratios and corresponding 95% CI. Results Baseline demographic and clinical characteristics were comparable among the three groups. Increasing MPV was associated with progressively lower platelet counts, reduced dialysis adequacy (URR), lower hemoglobin and serum albumin concentrations, and higher erythropoiesis-stimulating agent (ESA) requirements (all p<0.001). MPV correlated positively with weekly ESA dose (r=0.644; p=0.002). Five-year survival declined from 86.8% in the lowest MPV group to 71.9% and 46.4% in the intermediate and high MPV groups, respectively (log-rank χ²=12.69; p=0.0018). Patients with MPV >11.0 fL had a significantly higher risk of all-cause mortality than those with MPV <10.0 fL (HR 5.45; 95% CI 1.98-15.02; p=0.001). In univariable Cox regression, patients with MPV >11.0 fL had a significantly higher hazard of all-cause mortality than those with MPV <10.0 fL (HR 5.45; 95% CI 1.98-15.02; p=0.001). Each 0.01-unit increase in MPR was associated with a 49% higher hazard of death (HR 1.49; 95% CI 1.15-2.28; p<0.001). Cardiovascular mortality also increased progressively with higher MPV values. Discussion The findings suggest that increased platelet activation, reflected by elevated MPV and MPR, is associated with adverse clinical outcomes in maintenance HD patients. MPR showed a strong association with all-cause mortality and may provide complementary prognostic information to MPV alone. These results are consistent with the concept that platelet activation contributes to the chronic inflammatory and thrombotic milieu characteristic of end-stage kidney disease. However, given the retrospective observational design and lack of multivariable adjustment, these findings should be interpreted as hypothesis-generating. Conclusions Elevated MPV and MPR were associated with impaired dialysis adequacy, greater ESA requirements, lower hemoglobin and albumin concentrations, increased cardiovascular mortality, and reduced long-term survival. As inexpensive and routinely available hematological indices, MPV and MPR may have potential value for risk stratification in maintenance HD patients.