Treatment of acquired Thrombotic Thrombocytopenic Purpura in the U.S. remains heterogeneous: Current and future points of clinical equipoise.

BACKGROUND: The purpose of this survey was to describe current practices in the U.S. for treatment of acquired Thrombotic Thrombocytopenic Purpura (TTP), compare these with prior U.S. and current Canadian practices, and identify areas of clinical equipoise. STUDY DESIGN AND METHODS: A research team member administered the survey by telephone. Questions included an estimate of the annual patient volume treated, apheresis and medical therapy practices for acquired TTP. RESULTS: 32 centers from 22 states were surveyed. ADAMTS13 activity is used for confirmation of the diagnosis of acquired TTP (97%). Most commonly, daily plasma exchange (therapeutic plasma exchange [TPE]) is initiated with plasma as replacement fluid (91%) at 1.0 Plasma Volume (72%) and stopped with a platelet count of 150 × 109 /L (66%), and then TPE is tapered off (69%). Compared with a U.S. survey from 1998, a greater proportion of centers use plasma exclusively as the replacement fluid exclusively (29/32 vs 2/14 in 1998; P < .0001) and taper TPE (22/32 vs 8/20 in 1998, P = .0499). Compared with Canadian survey in 2016, a greater proportion of U.S. centers use plasma over cryosupernatant (29/32 vs 2/13 CAG centers, P < .0001) and initiate TPE with 1.0 PV compared with 1.5 PV (23/32 vs 0/14 CAG centers, P < .0001). Corticosteroid use is common but not universal (U.S. and CAG) and use of rituximab heterogeneous. CONCLUSION: Treatment of acquired TTP in the U.S. remains heterogeneous. Points of clinical equipoise identified were PV exchanged (1.0 vs >1.0), tapering of TPE versus none, and rituximab use.

Addressing the risk of bacterial contamination in platelets: a hospital economic perspective.

BACKGROUND: Bacterially contaminated platelets (PLTs) remain a serious risk. The Food and Drug Administration has issued draft guidance recommending hospitals implement secondary testing or transfuse PLTs that have been treated with pathogen reduction technology (PRT). The cost implications of these approaches are not well understood. STUDY DESIGN AND METHODS: We modeled incurred costs when hospitals acquire, process, and transfuse PLTs that are PRT treated with INTERCEPT (Cerus Corp.) or secondary tested with the PLT PGD Test (Verax Biomedical). RESULTS: Hospitals will spend $221.27 (30.0%) more per PRT-treated apheresis PLT unit administered compared to a Zika-tested apheresis PLT unit that is irradiated and PGD tested in hospital. This difference is reflected in PRT PLT units having: 1) a higher hospital purchase price ($100.00 additional charge compared to an untreated PLT); 2) lower therapeutic effectiveness than untreated PLTs among hematologic-oncologic patients, which contributes to additional transfusions ($96.05); or 3) fewer PLT storage days, which contributes to higher outdating cost from expired PLTs ($67.87). Only a small portion of the incremental costs for PRT-treated PLTs are offset by costs that may be avoided, including primary bacterial culture, secondary bacterial testing ($26.65), hospital irradiation ($8.50), Zika testing ($4.47), and other costs ($3.03). CONCLUSION: The significantly higher cost of PRT-treated PLTs over PGD-tested PLTs should interest stakeholders. For hospitals that outdate PLTs, savings associated with expiration extension to 7 days by adding PGD testing will likely be substantially greater than the cost of implementing PGD-testing. Our findings might usefully inform a hospital's decision to select a particular blood safety approach.

Clinical decision support improves physician guideline adherence for laboratory monitoring of chronic kidney disease: a matched cohort study.

BACKGROUND: Guidelines exist for chronic kidney disease (CKD) but are not well implemented in clinical practice. We evaluated the impact of a guideline-based clinical decision support system (CDSS) on laboratory monitoring and achievement of laboratory targets in stage 3-4 CKD patients. METHODS: We performed a matched cohort study of 12,353 stage 3-4 CKD patients whose physicians opted to receive an automated guideline-based CDSS with CKD-related lab results, and 42,996 matched controls whose physicians did not receive the CDSS. Physicians were from US community-based physician practices utilizing a large, commercial laboratory (LabCorp®). We compared the percentage of laboratory tests obtained within guideline-recommended intervals and the percentage of results within guideline target ranges between CDSS and non-CDSS patients. Laboratory tests analyzed included estimated glomerular filtration rate, plasma parathyroid hormone, serum calcium, phosphorus, 25-hydroxy vitamin D (25-D), total carbon dioxide, transferrin saturation (TSAT), LDL cholesterol (LDL-C), blood hemoglobin, and urine protein measurements. RESULTS: Physicians who used the CDSS ordered all CKD-relevant testing more in accord with guidelines than those who did not use the system. Odds ratios favoring CDSS ranged from 1.29 (TSAT) to 1.88 (serum phosphorus) [CI, 1.20 to 2.01], p < 0.001 for all tests. The CDSS impact was greater for primary care physicians versus nephrologists. CDSS physicians met guideline targets for LDL-C and 25-D more often, but hemoglobin targets less often, than non-CDSS physicians. Use of CDSS did not impact guideline target achievement for the remaining tests. CONCLUSIONS: Use of an automated laboratory-based CDSS may improve physician adherence to guidelines with respect to timely monitoring of CKD.

How we approach an acquired thrombotic thrombocytopenic purpura patient.

Acquired thrombotic thrombocytopenic purpura (TTP) is a disease characterized by microangiopathic hemolytic anemia and thrombocytopenia, in addition to variable fever and neurologic and renal dysfunction, without an underlying cause. Recent advances in elucidating the pathophysiology of acquired TTP have led to new testing that we have incorporated into our current management of patients with suspected acquired TTP. Despite these developments, much of the treatment for acquired TTP beyond therapeutic plasma exchange (TPE) is based on low-quality evidence. Our group has a sustained interest in studying and optimizing the use of TPE, along with other concurrent therapies, in acquired TTP patients. Described herein is a summary of how our apheresis consult service approaches requests for TPE in patients with suspected acquired TTP.

Thrombotic thrombocytopenic purpura: 2012 American Society for Apheresis (ASFA) consensus conference on classification, diagnosis, management, and future research.

The American Society for Apheresis (ASFA) conducted a 1 day consensus conference on Thrombotic Thrombocytopenic Purpura (TTP) during its annual meeting in Atlanta, GA, on April 10, 2012. The authors of this article, a subcommittee of ASFA's Clinical Applications Committee, developed several questions with regard to definitions, classification, pathophysiology, diagnosis, management, and future research in TTP. These questions were provided to the seven invited speakers who are the experts in the field of TTP. Two moderators conducted the proceedings of the conference which was attended by more than 100 participants. After each presentation, there was an open discussion that included moderator-selected written questions submitted by the audience. A medical writer-generated transcript of the proceedings as well as each presentation was made available to the authors. Each summary was reviewed and approved by the respective speaker before submission of this article. The subcommittee also developed seven key questions for blinded, electronic polling conducted by the moderators to generate a consensus amongst the speakers. This article includes these presentation summaries as well as results of the electronic poll.

Dose of prophylactic platelet transfusions and prevention of hemorrhage.

BACKGROUND: We conducted a trial of prophylactic platelet transfusions to evaluate the effect of platelet dose on bleeding in patients with hypoproliferative thrombocytopenia. METHODS: We randomly assigned hospitalized patients undergoing hematopoietic stem-cell transplantation or chemotherapy for hematologic cancers or solid tumors to receive prophylactic platelet transfusions at a low dose, a medium dose, or a high dose (1.1x10(11), 2.2x10(11), or 4.4x10(11) platelets per square meter of body-surface area, respectively), when morning platelet counts were 10,000 per cubic millimeter or lower. Clinical signs of bleeding were assessed daily. The primary end point was bleeding of grade 2 or higher (as defined on the basis of World Health Organization criteria). RESULTS: In the 1272 patients who received at least one platelet transfusion, the primary end point was observed in 71%, 69%, and 70% of the patients in the low-dose group, the medium-dose group, and the high-dose group, respectively (differences were not significant). The incidences of higher grades of bleeding, and other adverse events, were similar among the three groups. The median number of platelets transfused was significantly lower in the low-dose group (9.25x10(11)) than in the medium-dose group (11.25x10(11)) or the high-dose group (19.63x10(11)) (P=0.002 for low vs. medium, P<0.001 for high vs. low and high vs. medium), but the median number of platelet transfusions given was significantly higher in the low-dose group (five, vs. three in the medium-dose and three in the high-dose group; P<0.001 for low vs. medium and low vs. high). Bleeding occurred on 25% of the study days on which morning platelet counts were 5000 per cubic millimeter or lower, as compared with 17% of study days on which platelet counts were 6000 to 80,000 per cubic millimeter (P<0.001). CONCLUSIONS: Low doses of platelets administered as a prophylactic transfusion led to a decreased number of platelets transfused per patient but an increased number of transfusions given. At doses between 1.1x10(11) and 4.4x10(11) platelets per square meter, the number of platelets in the prophylactic transfusion had no effect on the incidence of bleeding. (ClinicalTrials.gov number, NCT00128713.)

Survey of methods used to detect bacterial contamination of platelet products in the United States in 2011.

BACKGROUND: Testing of platelets (PLTs) for bacterial contamination is required by the AABB Standards but is not fully standardized. On January 31, 2011, a new AABB Standard, 5.1.5.1.1, specified that bacterial detection methods for PLT components shall use assays either approved by the Food and Drug Administration (FDA) or validated to provide sensitivity equivalent to these FDA-approved methods. METHODS: An Internet-based survey of AABB member institutions was conducted from May to June 2012, to document current practices used in 2011 for bacterial detection in different PLT products and to assess the impact of the new standard. RESULTS: Of 1053 AABB member institutions surveyed, 40 of 99 blood centers (40.4%) and 184 of 954 hospital blood banks or transfusion services (19.3%) responded. Sixty-four respondents manufactured PLTs. Apheresis PLTs (APs) were predominantly screened with the BacT/ALERT system (89.5%); the majority (95.2%) were cultured with at least 8 mL of product. There was substantial variation in the minimum incubation time of cultures before release of PLTs (range, 0 to >24 hr). Recalls of released AP for possible bacterial contamination were largely successful (67.3%); successful interdiction before transfusion was associated with incubation for more than 12 hours before release (p < 0.01). After Standard 5.1.5.1.1 took effect, there was a decrease in production of whole blood-derived PLT concentrates (WBPCs). Point-of-issue ("rapid") immunoassays were used to screen a substantial proportion of WBPC PLTs, but were rarely used as secondary tests for previously cultured APs. CONCLUSION: The survey identified variability in culture methods and release times with AP, while use of WBPC decreased after AABB Standard 5.1.5.1.1 became effective.

Validation of a microbial detection system for use with ACD-A platelets with PAS III platelet additive solution.

BACKGROUND: The BacT/ALERT microbial detection system (BTA) is used for testing leukoreduced apheresis platelets (LR-AP) in plasma. Platelet additive solutions (PASs) such as InterSol (PAS III) may be used to reduce the amount of plasma transfused in LR-AP. This study evaluated the performance of the two-bottle BTA testing scheme in the recovery of seeded microorganisms from LR-AP in InterSol-plasma compared to a reference plate culture method. STUDY DESIGN AND METHODS: Hyperconcentrated, double LR-AP were collected from healthy donors; InterSol was added (65% Intersol:35% plasma), equally divided into two containers, and then inoculated with an isolate of 1 of 10 clinically relevant index organisms at two levels. Aerobic (BPA) and anaerobic (BPN) BTA bottles were inoculated with 4 mL each of the inoculated LR-AP, and blood agar plates (BAPs) for aerobic and anaerobic culture (0.5 mL each). RESULTS: Zero false-positives from 103 bottle pairs were observed. All 400 two-bottle BTA tests were positive within 24 hours, except for Propionibacterium acnes (maximum time-to-detection of 86.4 hr) and 13 of 20 pairs of Streptococcus viridans (maximum time-to-detection of 31.7 hr). Thirteen of 400 BAP two-plate tests were negative for starting bacterial concentrations of 10 colony-forming units (CFUs)/mL or less. At 40 CFUs/mL or less, BTA was 100% positive while BAP was 94% positive. CONCLUSION: Seeded organism recovery was superior in the two-bottle BTA test system compared to the two-plate BAP system using InterSol platelets (PLTs). This performance is comparable to previously published results for PLTs in plasma. The use of InterSol does not appear to have a detrimental effect on the performance of the two-bottle BTA system.

Rapid increases in parasitemia following red cell exchange for malaria.

Exchange transfusion is frequently used as an adjunctive treatment of severe malaria, although the efficacy of exchange transfusion as therapy for severe malaria remains controversial. The major perceived benefit of exchange transfusion is the rapid reduction of parasite load. However, no previous report has shown the dynamic change in parasitemia shortly following an acute load reduction. We report a 20-year-female who developed cerebral malaria and 30% parasitemia after traveling to Africa. In addition to antimalarial treatment, red cell exchange (RCX) was begun emergently with an automated blood-cell separator. Parasitemia dropped from 30 to 15% immediately after the procedure but rapidly increased to 25% after 50 min. The second procedure was performed 12 h after the first procedure. Her neurologic status returned to baseline on Day 2, and she was discharged on Day 6. Rapid increases in parasitemia can be observed after mechanical load reduction following RCX.

The impact of discontinuation of 7-day storage of apheresis platelets (PASSPORT) on recipient safety: an illustration of the need for proper risk assessments.

BACKGROUND: Seven-day stored apheresis platelets (APs) were withdrawn from the US market after detection of two culture-positive units from 2571 tested at outdate in the PASSPORT surveillance study. The impact of this discontinuation on recipient safety was explored using mathematical modeling. STUDY DESIGN AND METHODS: Risk models for septic transfusion reactions (STRs) and transfusion-related acute lung injury (TRALI) were developed. Key assumptions were 400,000 annual APs transfused, equivalent STR risk for platelets (PLTs) stored for 5 days or more and zero for PLTs stored for less than 5 days, whole blood-derived PLTs (WBplts) administered in 5-unit pools, a 4.6-fold higher risk of false-negatives with surrogate versus culture-based bacterial testing, an AP TRALI risk between 1 per 1000 and 1 per 10,000, and a delay in TRALI risk reduction implementation in some centers by 6 to 12 months due to limited PLT availability. RESULTS: STR risk could increase, decrease, or remain the same depending on the percentage of inventory replaced by surrogate-tested WBplts versus culture-tested apheresis or whole blood PLTs. A delay in TRALI risk reduction implementation is likely to result in a comparable or greater risk during the delayed implementation period than the safety achieved with regard to STRs, even in the most favorable case scenario. CONCLUSION: A comprehensive risk assessment should have been conducted before the decision to discontinue PASSPORT. Risk assessments using accepted methods (and actual data when available) should precede any major blood safety decisions.

ADAMTS13 activity levels in patients with human immunodeficiency virus-associated thrombotic microangiopathy and profound CD4 deficiency.

BACKGROUND: Thrombotic microangiopathy (TMA) encompasses a number of disorders with hemolytic anemia and thrombocytopenia, including thrombotic thrombocytopenic purpura (TTP). A deficiency in ADAMTS13 enzyme levels, along with an inhibitory antibody, is found in most patients with idiopathic TTP. Patients with human immunodeficiency virus (HIV) infection can have a TTP-like illness; however, it appears to have a different etiology. METHODS: A retrospective review of patients who had an ADAMTS13 activity level performed from 2005 through 2007 was completed. Patients with a diagnosis of HIV infection with TMA were investigated. RESULTS: Two patients were identified. Case 1: a 47-year-old man with HIV infection and a CD4 count <10/microL presented with altered mental status, pneumonia, acute renal failure, thrombocytopenia, and anemia. The ADAMTS13 level was 71%. He was treated with plasma infusion. Two days after admission, he expired because of respiratory distress syndrome and metabolic lactic acidosis. Case 2: a 39-year-old man with HIV infection and a CD4 count of 9/microL presented with chest pain, acute renal failure, thrombocytopenia, and anemia. The ADAMTS13 level was 65%. He received multiple units of fresh frozen plasma without significant improvement in his platelet count. Six days after admission, the patient began highly active antiretroviral therapy, which resulted in a rapid increase in his platelet count. CONCLUSIONS: HIV-associated TMA is postulated to have a different pathophysiology than idiopathic TTP. This study supports that assumption because both patients exhibited many of the classic findings of TTP but did not have a deficiency of ADAMTS13.

Is it quinine TTP/HUS or quinine TMA? ADAMTS13 levels and implications for therapy.

Thrombocytopenia with or without microangiopathy following quinine is often referred to as quinine "hypersensitivity." When schistocytes are present it is frequently termed "quinine-associated TTP/HUS." A severe deficiency of the vWF-cleaving protease, ADAMTS13, is associated with idiopathic TTP. A previous study of patients with "quinine-associated TTP/HUS" found that ADAMTS13 activities were not abnormal in 12/12 patients. A retrospective review of TTP patients with quinine-associated thrombotic microangiopathy (TMA) for whom ADAMTS13 was measured before plasma exchange was performed. Six patients were identified. All were females (age range: 43 to 73, mean = 61.7 years) and had taken quinine for leg cramps. Four of the six experienced renal failure requiring dialysis. Five of the patients had D-Dimers levels measured, all were elevated. In four patients the levels were > or = 18 times the upper limit of normal. ADAMTS13 was normal in four patients and mildly decreased in two patients. We conclude that while thrombocytopenia and schistocytosis can be seen in quinine-associated TTP/HUS, the pathophysiology seems to be distinct from that seen in most cases of idiopathic TTP (i.e., severely decreased ADAMTS13 with an inhibitor). We recommend that a TMA in association with quinine be consistently referred to as quinine-associated thrombotic microangiopathy (quinine-TMA) to better distinguish this entity from idiopathic TTP. The use of plasma exchange in quinine-TMA is called into question.

Is it HIV TTP or HIV-associated thrombotic microangiopathy?

Thrombocytopenia is a common complication of Human Immunodeficiency Virus (HIV) infection. With advanced HIV disease, the presence of both thrombocytopenia and schistocytosis are frequently observed. In such cases, the diagnosis of HIV associated TTP is often considered. This article reviews emerging concepts of HIV associated microangiopathies. It concludes that the pathophysiology, in many cases seems to be distinct from idiopathic TTP (particularly with advanced HIV disease-<100 CD4/microliter). A sine que non for successful therapy of HIV-TMA appears to be the treatment of the underlying HIV infection.

Predictive Value of Schistocytes in Recurrence of Acquired Thrombotic Thrombocytopenic Purpura With Severe ADAMTS13 Deficiency at Discontinuation of Daily Therapeutic Plasma Exchange.

Acquired thrombotic thrombocytopenic purpura (TTP) is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and commonly ADAMTS13 deficiency. Patients with TTP and severe ADAMTS13 deficiency have high risk of disease recurrence, yet the ability to predict which patients will have recurrence remains limited. We assessed whether the presence of persistent schistocytes in TTP patients with severe ADAMTS13 deficiency at the time of daily therapeutic plasma exchange (TPE) discontinuation was predictive of disease recurrence. We retrospectively reviewed the electronic medical records of all patients with a diagnosis of TTP treated with TPE at our university medical center between August 1991 and April 2013. Exacerbation was defined as disease recurrence within 30 days of cessation of daily TPE, and relapse was defined as disease recurrence >30 days after cessation of daily TPE. Comparisons were performed with a two-sided Fisher's exact test or χ2 test. Of the 46 total TTP patients eligible for analysis, nine had residual schistocytosis (20%), four of the nine (44%) had exacerbations, and two of the nine (22%) relapsed. Of the 37 patients without residual schistocytosis, 16 (43%) had exacerbations and 11 (30%) relapsed. There were no statistically significant differences in the exacerbation or relapse rates with or without residual schistocytosis (P = 1.00 and 1.00, respectively). Residual schistocytes after discontinuation of daily TPE were not uncommon. The persistence of schistocytes had poor sensitivity, specificity, and both positive and negative predictive values. After the initial diagnosis of TTP is made, there is no reason to continue documenting the presence or absence of schistocytes.

Update on multi-center clinical trials in the United States.

This article reviews numerous multi-center clinical trials, either ongoing or in planning stages, which involve diverse clinical applications and emerging technologies in apheresis and transfusion medicine. The investigations summarized herein involve the following specific areas: platelet dosing strategy, thrombotic thrombocytopenia purpura, inflammatory bowel disease, seven-day platelet storage, dendritic cell vaccines, and age-related macular degeneration.