LAUSR

To the Editor: The creation of clinical registries for disease characterization and treatment has been performed in a variety of pathologies spanning multiple disciplines. With emerging diseases requiring analysis and known ones needing updates based on new discoveries, it is critical to heed the lessons learned from past registry development efforts [1,2]. Common lessons include designing a registry to (1) analyze data from patients with a specific disease pathophysiology, (2) assist in answering a focused clinical question(s), and (3) form a strong, integrated network of collaborators to answer the inevitable future questions that will arise. Metjian et al. have recently published their experience in establishing the Thrombotic Microangiopathy Registry of North America (TRNA) that endeavors to capture demographic, disease, and treatment data on any patient with thrombotic microangiopathy (TMA) [3]. While ambitious, this effort ignores the common lessons outlined above. The goals of this group are to: (1) “design and develop a registry to define ‘best practices’ for the diagnosis, treatment, and management of TMA, (2) develop a platform for conducting observational and interventional clinical trials, and (3) establish a national biorepository of samples from patients with TMA to facilitate future studies.” However, it is important to keep in mind that TMA represents a constellation of distinct disorders with different underlying pathophysiologies characterized by the overlapping findings of thrombocytopenia and microangiopathic hemolytic anemia. Additionally, no specific clinical questions have been asked. By virtue of these facts alone, the TRNA will struggle with the same inherent challenges that other general TMA registries have had—accrual of sufficient numbers of patients with a homogeneous disease process and concomitant gathering of relevant clinical data that is amenable to meaningful analysis with the opportunity to directly impact patient care. In contrast, the American Society for Apheresis (ASFA) Apheresis Registry Subcommittee, housed within the broader Clinical Applications Committee, is interested in further characterizing patients with a very specific TMA: severely ADAMTS13 deficient acquired thrombotic thrombocytopenic purpura (TTP). Despite the developments in understanding acquired TTP pathophysiology, much of the treatment for this unique autoimmune TMA beyond implementation of therapeutic plasma exchange (TPE) is based on low-quality evidence from relatively small studies. Thus, to address this deficit, ASFA investigators are currently establishing an apheresis registry to answer three specific apheresis-centric questions that would have a significant and immediate impact on how TPE is performed for these patients: (1) does performance of TPE with 1.5 plasma volume versus 1.0 plasma volume impact time to treatment response or risk of disease exacerbation, (2) does utilization of a TPE taper after achieving treatment response alter the risk of disease exacerbation, and (3) does a replacement fluid regimen of all plasma versus half albumin/half plasma impact time to treatment response or risk of disease exacerbation?