Use of blood parameters for the prediction of mortality in patients with below‑knee amputation

The present retrospective study aimed to investigate the value of blood parameters in predicting mortality in patients with below-knee amputation (BKA). A total of 178 patients with BKA were included in the present study. The patients were divided into two groups, namely the exitus group (n=136; 76.4%) and the survivors group (n=42; 23.6%). Patients in the exitus group were further divided into three subgroups: i) Those who experienced mortality in <1 month (n=55; 40.4%); ii) those who experienced mortality between 1-12 months (n=48; 35.3%); and iii) those who experienced mortality in >12 months after surgery (n=33; 24.3%). Binary logistic regression and a generalized linear model were used for relational analysis, and a receiver operator characteristic curve was used for diagnostic tests. It was found that the parameters of age (B=0.061; P=0.01), eosinophil-to-lymphocyte ratio (ELR) (B=-2.861; P<0.05), C-reactive protein (CRP)/albumin ratio (B=0.027; P<0.01) and mean platelet volume (MPV)/lymphocyte ratio (B=0.310; P<0.01) had a significant effect on mortality at the multivariate level. Moreover, regression coefficients showed that the effect of age, CRP/albumin and MPV/lymphocyte ratios on mortality were positive, whereas the effect of the ELR was negative. The mortality predictive values of age [area under the curve (AUC)=0.681; P=0.01], ELR (AUC=0.630; P=0.01), CRP/albumin ratio (AUC=0.746; P=0.01) and MPV/lymphocyte ratio (AUC=0.676; P<0.01) were also found to be statistically significant. For the 27.51 CRP/albumin cut-off value, the sensitivity was found to be 80.1%, whereas the specificity was 54.8%. For the 36.93 CRP/albumin cut-off value, the sensitivity was 71.3%, and the specificity was 73.8%. Furthermore, MPV (B=-0.37; P<0.01) and hemoglobin/red-blood-cell distribution width (RDW) ratio (B=5.20; P<0.01) were found to have a significant effect on the time to death at the multivariate level. The parameters MPV (AUC=0.648; P<0.01) and hemoglobin/RDW (AUC=0.673; P=0.01) had predictive value in terms of the time to death. The predictive value for MPV was found to be 64.8%, whereas that for the hemoglobin/RDW ratio was 67.3%. For the 0.54 cut-off value for hemoglobin/RDW, the sensitivity was 74.5%, and the specificity was 11.1%. By contrast, for the 0.84 cut-off value for the hemoglobin/RDW ratio, the sensitivity was 10.9% and the specificity was 81.5%. In conclusion, the CRP/albumin ratio was identified as a significant mortality parameter, whereas the hemoglobin/RDW ratio was a significant time to death predictor, according to the results of the present analysis. These results may guide clinical practices and further research in terms of predicting mortality in patients with BKA.