Outcomes of patients with thrombotic thrombocytopenic purpura treated in an intensive care unit

Background Thrombotic thrombocytopenic purpura (TTP) is a multisystem disorder characterized by widespread microthrombosis that can predispose to multiple organ failure. The literature is sparse on the outcomes of critically ill patients with TTP managed in intensive care units (ICUs). We aimed to determine the mortality of ICU patients admitted with TTP and evaluate the predictors of survival. We also compared the incidence of nosocomial infection among those who did or did not receive plasma exchange (PE). Methods We conducted a retrospective study in a tertiary ICU. Two authors screened patients for eligibility from the hospital information system based on peripheral smear reports. Adult critically ill TTP patients managed in ICU were included. Patients with a diagnosis of haemolytic uraemic syndrome, autoimmune causes of haemolysis and pregnancy-related conditions, etc. were excluded. Two authors extracted data from medical charts. No imputation of missing variables was done. Non-parametric statistics were used to report data. Statistical analyses were performed using Stata version 16. Results Of the 535 records that were screened, 33 patients were deemed eligible. Mortality among TTP patients was 14 (42%). The women to men ratio was 7:3. At admission, greater degree of anaemia, thrombocytopenia, and higher lactate dehydrogenase levels were observed in non-survivors compared to survivors (5.4 g/dl [4.8-7.1] v. 7.6 g/dl [6.1-8.9], p=0.05; 17x103 μl v. 21x103 μl, p=0.63; and 2987 (1904-3614) U/L v. 2126 U/L (1941-3319), p=0.71; respectively]. Nineteen (57%) patients had acute kidney injury (AKI), of which 11 survived: 6 recovered completely from renal failure and 5 progressed to end-stage renal disease. Nosocomial infection rates were not different among those receiving and not receiving PE therapy (7 [33%] v. 3 [25%], respectively). Conclusion TTP is more common in women and has a high mortality. Older age, low haemoglobin and higher platelet transfusions are predictors of poor survival. Nosocomial infection rates were similar irrespective of receiving PE therapy.