Improving the PLASMIC score with the use of RDW-SD in the differential diagnosis for thrombotic thrombocytopenic purpura in Chinese patients.

BackgroundThis study aimed to identify laboratory parameters that could optimize the PLASMIC score, thereby improving its diagnostic accuracy for thrombotic thrombocytopenic purpura (TTP).MethodsWe performed a retrospective analysis of 136 patients with suspected TTP who had available ADAMTS-13 activity measurements. Patients were stratified into two groups based on ADAMTS-13 activity: a TTP group (n = 49) and a non-TTP group (n = 87). Routine laboratory parameters-including hemoglobin (HGB), red blood cell distribution width-standard deviation (RDW-SD), mean corpuscular volume (MCV), platelet count (PLT), alanine aminotransferase (ALT), aspartate aminotransferase (AST), direct bilirubin (DBIL), indirect bilirubin (IBIL), lactate dehydrogenase (LDH), creatinine (CR), urea (UREA), international normalized ratio (INR), and D-dimer-were compared between groups. Statistically significant parameters were selected as candidate variables to refine the PLASMIC score. The diagnostic performance of the modified model was evaluated using receiver operating characteristic (ROC) curve analysis.ResultsSix parameters-HGB, PLT, ALT, RDW-SD, IBIL, and LDH-demonstrated significant differences between TTP and non-TTP patients. Multivariate logistic regression identified RDW-SD, PLT, and LDH as independent predictors of TTP. Based on these findings, we revised the PLASMIC score by substituting MCV with RDW-SD. The modified model exhibited a higher area under the curve (AUC) (0.907 vs 0.817) while maintaining sensitivity (95.9%) and improving specificity (70.1% vs 65.9%) compared to the original.ConclusionThe modified PLASMIC score model may improve diagnostic accuracy for TTP in similar patient populations, but requires external validation in diverse cohorts to confirm its broader utility.