Apheresis and the thrombotic thrombocytopenic purpura syndrome: current advances in diagnosis, pathophysiology, and management

Therapeutic plasma exchange taper does not decrease exacerbations in immune thrombotic thrombocytopenic purpura patients

BACKGROUND

Despite rapid and intensive treatments with therapeutic plasma exchange (TPE) and immunosuppression, immune thrombotic thrombocytopenic purpura (TTP) patients are at risk of disease exacerbation, i.e., early recurrence of TTP within 30 days of achieving treatment response. TPE taper, a practice of performing additional TPE procedures after achieving treatment response, is commonly performed for decreasing exacerbations, although no evidence supports this practice.

STUDY DESIGN AND METHODS

In this prospective observational investigation over four years, our center switched its standard of care for treating all TTP patients from not performing TPE taper after achieving treatment response (i.e., no-taper cohort) to performance of TPE taper (i.e., yes-taper cohort) to characterize impacts on exacerbations. Continuous and categorical data were analyzed by Mann-Whitney, Fisher's exact, and log-rank tests; significance was defined as p < 0.05.

RESULTS

The two cohorts were well matched and had no significant differences in demographics, presentation laboratory values, or TTP history (p > 0.05 for all). The yes-taper cohort of 26 patients with 29 consecutive episodes did not have a significantly different exacerbation rate from the no-taper cohort of 24 patients with 27 consecutive episodes (exacerbation rates of 37.9% vs. 33.3%, respectively; p = 0.78); however, treatment-related complications directly attributed to the TPE procedures, blood products, or central venous catheters were significantly greater in the yes-taper cohort (nine vs. one events, respectively; p = 0.01).

CONCLUSION

Since TPE taper did not reduce exacerbations in our TTP patients, we no longer advocate for TPE taper and have reverted to our original standard of care.

Prognostic risk-stratified score for predicting mortality in hospitalized patients with thrombotic thrombocytopenic purpura: nationally representative data from 2007 to 2012

BACKGROUND

Despite proven efficacy and increased availability of therapeutic plasma exchange (TPE), mortality for patients with thrombotic thrombocytopenic purpura (TTP) remains high with a limited understanding of those at highest risk of death.

STUDY DESIGN AND METHODS

This study utilized the Nationwide Inpatient Sample (2007-2012) to derive a prognostic score for mortality in hospitalized TTP patients. Odds ratios of death with various putative risk factors adjusted for age, sex, and race were calculated (adjOR). Weighted mean of adjOR estimates were incorporated in a risk-stratified score.

RESULTS

Among 8203 hospitalizations with TTP as primary admission diagnosis who underwent TPE, 613 deaths were identified (all-cause mortality, 7.5%; median time-to-death, 9 days; interquartile range, 4-14 days). In multivariable logistic regression, arterial thrombosis (adjOR 6.7, 95% confidence interval [CI], 1.1-40.9), intracranial hemorrhage (adjOR, 6.1; 95% CI, 1.6-23.2), age at least 60 years (adjOR, 3.5; 95% CI, 2.1-5.6), renal failure (adjOR, 2.6; 95% CI, 1.5-4.5), ischemic stroke (adjOR, 2.4; 95% CI, 1.2-5.0), platelet (PLT) transfusions (adjOR, 2.2; 95% CI, 1.2-4.1), and myocardial infarction (adjOR, 2.3; 95% CI, 1.2-4.6) were significant independent predictors of mortality in TTP patients who underwent TPE. A prognostic weighted mortality prediction scoring system incorporating arterial thrombosis, intracranial hemorrhage, age, renal failure, ischemic stroke, PLT transfusion, and myocardial infarction showed very good discrimination and was predictive of 78.6% deaths.

CONCLUSIONS

Early and targeted therapy for high-risk individuals should be used to guide management of TTP patients for improved survival outcomes.

Anaemia in pregnancy

Anaemia in pregnancy, defined as a haemoglobin concentration (Hb) < 110 g/L, affects more than 56 million women globally, two thirds of them being from Asia. Multiple factors lead to anaemia in pregnancy, nutritional iron deficiency anaemia (IDA) being the commonest. Underlying inflammatory conditions, physiological haemodilution and several factors affecting Hb and iron status in pregnancy lead to difficulties in establishing a definitive diagnosis. IDA is associated with increased maternal and perinatal morbidity and mortality, and long-term adverse effects in the new born. Strategies to prevent anaemia in pregnancy and its adverse effects include treatment of underlying conditions, iron and folate supplementation given weekly for all menstruating women including adolescents and daily for women during pregnancy and the post partum period, and delayed clamping of the umbilical cord at delivery. Oral iron is preferable to intravenous therapy for treatment of IDA. B12 and folate deficiencies in pregnancy are rare and may be due to inadequate dietary intake with the latter being more common. These vitamins play an important role in embryo genesis and hence any relative deficiencies may result in congenital abnormalities. Finding the underlying cause are crucial to the management of these deficiencies. Haemolytic anaemias rare also rare in pregnancy, but may have life-threatening complications if the diagnosis is not made in good time and acted upon appropriately.

Thrombotic thrombocytopenic purpura/haemolytic uraemic syndrome: a new index predicting response to plasma exchange

Despite the favourable response of thrombotic thrombocytopenic purpura/haemolytic uraemic syndrome (TTP/HUS) to plasma exchange, an early level of mortality persists. Non-response has been associated with a low frequency of exchange. The Rose index of TTP/HUS severity, occasionally used to predict the response of TTP/HUS to plasma exchange, remains unsatisfactory. The purpose of this study was to develop a new index predicting response of TTP/HUS to plasma exchange and to compare it with the Rose index. Retrospective analysis of 171 cases of TTP/HUS from 39 apheresis units across Canada between 1980 and 2001 was conducted. Logistic regression analysis was used to derive a model predicting 6-month mortality from presenting characteristics. The reduced model contained age >40 years, haemoglobin <9.0 g/dl and the presence of a fever at presentation. Gender, platelet count, creatinine and neurological signs were not part of the final model. This model predicted 13.4% of outcome variance. Predictive scores of 0, 2, 4 and 6 correlated with 6-month mortality rates of 12.5%, 14.0%, 31.3% and 61.5% respectively in our source population. This simple model may help identify those patients who would benefit from higher treatment intensity.

A case study of thrombotic thrombocytopaenic purpura: a 'powerful poison'

This paper presents the case of a previously well 72 year old man who spent 86 days in the intensive care unit (ICU) following a remarkable and explosive presentation of the rare condition thrombotic thrombocytopaenic purpura (TTP). TTP is an intravascular platelet aggregation disorder that, without treatment, is associated with significantly high mortality rates. This paper discusses TTP in terms of its presentation, pathophysiology, diagnosis and management. In addition to TTP, the patient developed a number of comorbidities during his stay in ICU. Particular attention is given to two major problems: acute renal failure and prolonged encephalopathy. These issues, along with the initial diagnosis of TTP, resulted in the patient remaining in ICU for a longer period than otherwise might have been expected. Despite many obstacles, the patient recovered and was discharged from hospital 116 days after initial presentation.

Therapeutic plasma exchange and plasma infusion in thrombotic microvascular syndromes

Plasma exchange (PE) is the most important treatment in thrombotic microangiopathies (TMAs) mainly encompassing thrombotic thrombocytopenic purpura (TTP) and adult hemolytic syndrome (HUS). This therapeutic measure has substantially improved clinical outcome. One plasma volume corresponding to 40 ml/kg of body weight is exchanged daily until the platelet count is above 150 x 10(9)/l or 100 x 10(9)/l and continues to rise or remains constantly after cessation of treatment. Exacerbations and late recurrences demand reapplication of daily PE. Twice daily PEs are initiated if the response to initial treatment is poor. The importance of additional or alternate measures including glucocorticoids, antiplatelet agents, splenectomy, intravenous immunoglobulins, protein A columns, vincristine, cyclosporine, and cyclophosphamide is uncertain. Whether cryosupernatant plasma (CSP) or solvent/detergent-treated (SDP) plasma is superior to standard fresh frozen plasma (FFP) remains to be determined. Methylene blue-treated plasma (MBP) seems to be less effective than standard FFP.

Thrombotic thrombocytopenic purpura associated with clopidogrel administration: case report and brief review

Clopidogrel has replaced ticlopidine (in the United States but not worldwide). Clopidogrel can either be used independently or in combination with other antiplatelet agents. Clopidogrel has a lower frequency of associated thrombotic thrombocytopenic purpura than ticlopidine, a lower rate of neutropenia, and better gastrointestinal tolerance. We describe a case of thrombotic thrombocytopenic purpura associated with the use of clopidogrel after percutaneous transluminal angioplasty and stent placement. Discontinuation of the drug and transfusion of 17 units of cryodepleted plasma resulted in resolution of the hematological abnormalities. Clinicians should be alert to this adverse effect of clopidogrel and monitor platelet counts in patients receiving it.