Severe Aplastic Anemia (SAA) in Colombia: Characteristics and Treatment in 6 Centers
Authors: Abello Virginia , Sossa Claudia , Omaña Paola , Galvez Kenny Mauricio , Pardo Carlos Alberto , Osuna Monica , Peña Angela María , Salazar Luis Antonio , Jimenez Sara Ines , Solano Maria Helena , Casas Claudia Patricia , Daniel Espinosa , Chaparro Mauricio , Linares Adriana , Estupiñan Marcela , Patiño Bonell , Prchal Josef T. 
Published: October 2019

Abstract
Introduction
Acquired severe aplastic anemia (SAA) is a low frequency hematologic disease associated with significant morbidity and mortality. The destruction by immunological mechanisms of hematopoietic progenitor cells appears to play a fundamental role in the pathophysiology of the disease, therefore, immunosuppressive treatment (IST) is one of the pillars of management. In Colombia and Latin-America there is lack of information about the characteristics of patients with SAA and the effectiveness of IST and other treatments. The main objective of this study was to assess the outcomes of a group of patients treated in different centers in Colombia during the last five years.
Materials and methods
This is a retrospective observational study, carried out within 6 institutions of 3 Colombian cities (Bogota, Medellín, Bucaramanga) of patients treated from 2013 to 2018. An anonymized database was constructed. All patients diagnosed with SAA and treated with IST as first line of therapy were included.
Results
We analyzed the data of 37 patients; 22 of them were women. The average age was 37 years old (with a range of 7-68 years). The median time since the onset of the symptoms to the time of diagnosis was 88 days (with a range of 7-655 days). Clastogenic effect of diepoxybutane (DEB) tests were available only in 9 patients (7 of which were positive); Paroxysmal Nocturnal Hemoglobinuria (PNH) clone was detected in 9 of the 27 tested, all of which were under 5%. Mean leukocytes, hemoglobin concentration, and platelets at the moment of diagnosis were 3.090, 8.5 and 22.000. Bacterial infection was the most important clinical manifestation at diagnosis (in 16 of the 37 patients); 19 out of 37 patients had more than 5 red blood cell transfusions before the first treatment. As first line therapy, 25 patients received IST (most by antithymocyte globulin (ATG) of which 10 were treated with rabbit ATG, 12 with horse ATG and 3 combined with Eltrombopag); 4 patients had cyclosporin and prednisone, 2 had allogeneic transplant and 6 received other therapies. Those treated with IST patients, 8 had a complete response (CR) (32%), 6 had partial response (PR) (24%), 8 had no response (32%). 5 received a second course of IST and 3 had CR. 3 patients were lost in follow up. At a mean follow up of 18.7 months (1.7-65), 44% were alive in CR, 26% in PR, 9% were in relapse and 21% died. Causes of death were SAA related infection in 5 patients, transplant related in 1 and non-disease related in 1.
Conclusions
This is the first multicenter report of SAA treatment in Colombia, it includes children and adults, resulting in a very heterogeneous population. This preliminary information shows that there is a significant delay in the diagnosis and initiation of treatment in patients, most patients have more than 5 transfusions before treatment. This could, in part, explain the apparent low response rates to IST in comparison to that of what have been reported in literature. A larger registry of hematologic pathologies is required so we can confirm these findings, start proposing strategies applicable in our country to achieve better outcomes in these patients and planning clinical trials to answer questions relevant to our population.

Disclosures
No relevant conflicts of interest to declare.