PB0146 - Differentiating Thrombotic Thrombocytopenic Purpura from Other Thrombotic Microangiopathies at Royal Hospital: A retrospective study and a cost analysis

Sunday, June 23, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

MA

Maryam Al Saaidi

Hematopathology resident
Oman Medical Specialty Board
Muscat, Masqat, Oman

Co-Author(s)

Muntadhar Al Moosawi

Hematopathologist and laboratory coagulation consultant
Royal Hospital
Muscat, Masqat, Oman

Background: Thrombotic microangiopathies (TMAs) are rare disorders marked by microangiopathic hemolytic anemia, thrombocytopenia, and microthrombi causing ischemic tissue injury. Thrombotic thrombocytopenic purpura (TTP) stands out as a critical TMA variant due to ADAMTS13 enzyme deficiency. Treating TTP primarily involves plasma exchange transfusion (PLEX), which is costly and labor-intensive. Conversely, other TMAs are treated supportively. TTP's diagnosis is verified through ADAMTS13 activity levels. However, since ADAMTS13 results take about three weeks, other TMAs are often treated as TTP with multiple, potentially unnecessary PLEX sessions.

Aims: In this study, we sought to identify factors differentiating TTP from non-TTP TMAs. We also aimed to analyze the cost effectiveness of having a local ADAMTS13 assay.

Methods: In a retrospective study at Royal Hospital, we reviewed a 10 years of patient data for ADAMTS13 testing. We analyzed clinical and lab parameters to distinguish TTP from non-TTP TMAs.

Results: 134 patients were tested for ADAMTS13 in the period from 2013 to 2023. Sixty-four patients were included in the study (33 TTP and 31 non-TTP TMA). Of the TTP group, 26 patients had confirmed diagnosis of immune TTP (iTTP) based on ADAMTS13 testing, and hence were included in the comparison analysis. There was no difference in age or Hemoglobin levels between the two groups. However, platelet count and creatinine levels were significantly lower in the TTP group (figures 1 and 2). The majority of the TTP patients (92%) had high PLASMIC scores. Twenty-two patients in the non-TTP TMA group received PLEX, with a median of 5 PLEX sessions per patient. These are considered potentially preventable PELX sessions.

Conclusion(s): ADAMTS13 provided a confirmatory diagnosis of TTP. A cost analysis will be conducted to determine whether a local ADAMTS13 assay will be cost effective.