Background: Immune thrombotic thrombocytopenic purpura (iTTP) is a life-threatening thrombotic microangiopathy (TMA) driven by ADAMTS13 deficiency. Timely diagnosis is essential, with guidelines recommending ADAMTS13 results <72 hours(1). Unfortunately, many institutions face challenges, particularly in outpatient settings. In response, the United States Thrombotic Microangiopathy Alliance (USTMA) launched a grassroots program in 2023, FAST4TMA, offering the first ever, free, same-day ADAMTS13 testing, along with mobile phlebotomy for homebound patients(2).

Methods: FAST4TMA operates across the United States, coordinating testing via a centralized high-throughput reference lab. Eligible participants include both inpatients and outpatients with suspected or confirmed TMA. As part of continued quality improvement efforts, a follow-up provider survey was distributed to assess clinical utility and implementation outcomes from the initial survey(2). Economic savings were modeled using real program data and previously published cost-effectiveness estimates for rapid ADAMTS13 turnaround.

Results: From June 2023 - July 2025:

  • 420 ADAMTS13 samples received

  • 37 (8.8%) severe deficiency (<10%)

  • 132 (31.4%) moderate deficiency (10–60%)

  • 233 (55.5%) were >30% activity

  • 202 samples (48.1%) collected via mobile phlebotomy

  • 18 samples (4.3%) cancelled or not processed

  • 4 congenital TTP (cTTP) patients newly identified

  • Turnaround time consistently <24 hours for all completed samples.

Provider Feedback: Among provider respondents:

  • 100% agreed FAST4TMA improved patient care

  • 88% reported improved adherence to surveillance testing

  • Open-ended feedback emphasized ease of access, turnaround time, and reduced patient anxiety

Cost Impact: Economic modeling has shown that rapid ADAMTS13 testing yields $10,788 in per-patient hospital savings(3). Applying this to 402 total patients tested through FAST4TMA, the program may have saved approximately $4.34 million in downstream care costs. While inpatient cost savings dominate, outpatient monitoring prevented avoidable escalation and contributed to health system efficiency and quality of life improvements.

These findings are further supported other models showing delayed ADAMTS13 testing can result in significant overtreatment and unnecessary plasma exchange(4), supporting rapid ADAMST13 testing in improving clinical decision-making and reducing cost and morbidity in nearly half of suspected TTP cases.

Patient Benefit: Serial monitoring during remission revealed significant fluctuation in ADAMTS13 levels, identifying those needing therapy. Patients with quarterly testing were more likely to have relapses identified early, allowing for preemptive intervention and avoidance of emergency care. Pre-morbid diagnosis of cTTP is limited due to awareness and access to testing, with the diagnosis of cTTP commonly delayed for years, especially in milder phenotypes and adult presentations(5). Early diagnosis through programs like FAST4TMA enables timely initiation of prophylactic therapy, potentially reducing lifelong thrombotic risk and organ damage

Conclusion: As the first and only national ADAMTS13 monitoring program, FAST4TMA remains a scalable, cost-effective, and patient-centered model for improving TMA diagnosis and follow-up, allowing diagnosis prior to disease manifestation, as with cTTP, or preventing relapse, as with iTTP. The program's mobile phlebotomy access, rapid turnaround, and centralized coordination continue to reduce barriers to ADAMTS13 testing and can serve as a model for rare disease surveillance programs. Future directions include expanding inpatient use, monitoring replacement therapy, and continuing equity in access.

References:

  • George JN, Nester CM. Syndromes of thrombotic microangiopathy. N Engl J Med. 2014;371(7):654-666

  • Martin C, Metjian A, Lewis B., et al. FAST4TMA – Rapid Hospital-Based and out-patient ADAMTS13 testing. Blood (2023) 142 (Supplement 1): 2295

  • White A., Martin R, Dew K, et al. Economic impact of a rapid, on-demand ADAMTS-13 activity assay for the diagnosis of thrombotic thrombocytopenic purpura. Res Pract Thromb Haemost. 2022;6(6):e12711.

  • Kim CH, Simmons SC, Wattar SF, et al.. Potential impact of a delayed ADAMTS13 result in the treatment of thrombotic microangiopathy. Vox Sang. 2020;115(5):420–428. doi:10.1111/vox.12872

  • Alwan F, Vendramin C, Liesner R, et al. Characterization and treatment of congenital thrombotic thrombocytopenic purpura. Blood. 2019 Apr 11;133(15):1644-1651

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2025
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