OBJECTIVES: acquired Thrombotic Thrombocytopenic Purpura (aTTP) is a potentially life-threatening thrombotic microangiopathy (TMA) with a reported annual incidence varying between 1.5-6 cases per million in Europe. The objective is to assess, for the first time in Portugal, the incidence of aTTP patients and describe their main sociodemographic characteristics and outcomes.

METHODS: A cross-sectional study was performed on the entire NHS hospitals database from 2014 to 2018, with diagnosis and procedures coded using the International Classification of Diseases (ICD), 9^th and 10^th revisions. Although there are no ICD codes to specifically identify aTTP disease, we identified patients with a presumed TTP episode as: individuals with TMA [446.6 (ICD-9-CM) and M31.1 (ICD-10)] as admission diagnosis OR with TMA as secondary diagnosis with one of the following admission diagnoses: cardiomyopathy, cerebral infarction, HIV, nausea, pulmonary embolism and infarction, disorders of arteries and arterioles, puckering of macula, lupus, cerebral ischemia, or urinary tract infection; PLUS submitted to plasmapheresis [99.71(ICD-9-CM), 6A550Z3 and 6A551Z3 (ICD-10)]. Sociodemographic characteristics and main outcomes were analysed for these aTTP patients.

RESULTS: We identified 90 episodes of aTTP in 71 individuals. These patients are mostly females (69%) with an average of 46 years old (SD±17 years). Their most common comorbidities are hypertension, anemia, acute kidney failure, convulsions, hypopotassemia and hypokalemia. Around 21% of these individuals are hospitalized every year and stay on average 20 days (SD±20 days). The in-hospital mortality rate was 10%.

CONCLUSIONS: Our results confirm the rarity of aTTP and its severity in the Portuguese population, with a high in-hospital mortality rate, in line with the results reported in the literature for other countries. Since rapid recognition of aTTP is crucial, it is important to generate national data and increase awareness among the medical community for the fast identification of these patients and prompt initiation of target treatment to improve patient outcomes.