A recent article published in Thrombosis and Haemostasis suggests that platelet count measurement may be noninferior to other diagnostic systems for the early recognition of thrombotic thrombocytopenic purpura (TTP).
Thrombotic microangiopathy (TMA) represents a diverse set of diseases linked with peripheral thrombocytopenia and organ damage. While the specific pathophysiology for each member of the TMA set has not yet been identified, severely deficient ADAMTS13 activity is known to underlie TTP. Because up to 80% of patients with TTP will die without therapeutic plasma exchange, early recognition of the disease is essential for effective treatment.
In the TTP setting, ADAMTS13 activity measurement is sufficient for the recognition of TTP. However, because such measurement is limited to specialized laboratories, diagnosis can be delayed. For this study, researchers evaluated alternative diagnostic systems – the Coppo system and the PLASMIC score – for their effectiveness in TTP diagnosis in a group of critically ill patients with TMA.
Overall, 154 patients with TMA were included. Among patients with confirmed TTP (99 patients) and other TMA (55 patients), the average age was 44 vs 49 years, respectively; 70 (71%) vs 23 (41.8%) patients were female, 58 (58.6%) vs 21 (38.2%) patients had severe neurologic involvement or features, and 5 (5.1%) vs 25 (45.5%) patients had severe renal involvement or features. Hemoglobin levels, platelet counts, creatinine levels, and ADAMTS13 activity were all significantly higher in the other TMA group than in the TTP group.
Logistic regression analysis showed that the area under the receiver operating characteristic curve for TTP prediction was 0.86 (95% CI; 0.81-0.92) with the Coppo score vs 0.67 (95% CI: 0.58-0.76) with PLASMIC; further analysis suggested, however, that this figure was 0.86 (95% CI; 0.81-0.92) for platelet counts alone.
Platelet counts of 20 G/L or less were similarly effective for TTP diagnosis compared with the Coppo scoring system and superior to the PLASMIC system.
“In conclusion, in a French population of TMA patients requiring ICU admission, the Coppo score performed better than the PLASMIC score for the identification of acquired TTP cases,” the authors wrote. “Interestingly, considering the specific enrollment of our TTP-focused hyperspecialized center, our study emphasizes that platelet count is the most powerful parameter of the Coppo score to predict acquired TTP diagnosis.”
Disclosures: Some authors have declared affiliations with the pharmaceutical industry. Please refer to the original study for a full list of disclosures.
Mariotte E, Zafrani L, Fadlallah J, et al. Performance of diagnostic scores in thrombotic microangiopathy patients in the intensive care unit: a monocentric study. Thromb Haemost. Published online January 29, 2021. doi:10.1055/a-1378-3804