ABORhCard Applications and Performance Studies White Paper

Transcription

1 ABORhCard Applications and Performance Studies White Paper Contents Background ABORhCard Simple, Accurate, Fast Blood Typing Product Design Applications ABORhCard Principles/Procedure Result Interpretation Performance Studies Limitations References

2 Background Knowledge of an individual s blood type relies on two critical systems which, when combined, describe any 1 of 8 possible blood types in humans. The first system is based on Karl Landsteiner s 1901 Nobel Prize-winning discovery of the ABO blood group system 1. This discovery revolutionized the field of transfusion medicine by providing an answer to the confounding problem of why some human blood transfusions succeeded and others failed catastrophically. In 1941, the second discovery of the Rh system was identified and provided an even better understanding of hemolytic transfusion reactions and hemolytic disease of the newborn 2. The frequency of each blood type in the U.S. is shown below (Table 1). Table 1: ABO/Rh Blood Type Frequency in the United States 3 ABO Group Rh + Rh O 37% 7% A 35% 6% B 9% 2% AB 3% 1% ABORhCard Simple, Accurate, Fast Blood Typing The Micronics ABORhCard is a rapid, credit card sized test for the simultaneous determination of an individual s ABO and Rh type from a finger stick sample of whole blood. Results are available in approximately 2 minutes. It requires no instrumentation or refrigeration. The card s microfluidic channel design provides for an enclosed system that reduces exposure to blood borne pathogens and minimizes potential environmental contaminants. The ABORhCard can be an important tool to obtain a blood type quickly in laboratory and non-laboratory settings. Product Design The Micronics ABORhCard utilizes microfluidics the ability to reduce sample and reagent volumes and to process fluids in small channels to provide an agglutination test result. This technology is centered on the generation and use of Laminar Fluid Diffusion Interfaces ( LFDIs ) in diffusion-based reactive mixing. In the ABORhCard, the fresh whole blood sample stream and the hydrated antibody reagent stream are introduced into a common reaction channel and flow one on top of the other until they exit the channel. Agglutination results when particles, such as blood cells, are aggregated by formation of antigen: antibody affinity pairs at the interfacial boundary. Applications The ABORhCard is FDA 510(k) cleared for educational and informational purposes. Given this specific clearance and its operational versatility, the ABORhCard is an ideal rapid blood typing device for a variety of markets and settings. It should be noted, however, that the card is NOT for use for blood bank processing of blood products, for determining RHD status for the purpose of administration of Rh immunoglobulin or for screening purposes prior to transfusion. ABORhCard Applications and Performance Studies 2

3 To Support Blood Supply Management Around 107 million units of blood donations are collected globally every year 4. In the U.S. that number is 16 million 5. Most blood supplies are largely dependent on a steady base of voluntary blood donors. However, the balance of blood supply and medical demand is tenuous due to a number of limiting factors. Among these are the short shelf life of donated units, increased consumption during emergency response, and seasonal variances in donor availability. Due to these factors, blood centers have a need to improve efficiencies that diminish waste and allow flexibility in collection protocols to respond to specific needs on specific days. Many donor centers now employ apheresis collection methods where only the needed component is collected and the remaining blood is returned to the donor during the donation process. Among the many benefits, the donor can provide a greater volume of the needed component than with a traditional collection. Further, apheresis collection technology is not limited to the brick and mortar blood center, but can be found in mobile settings as well. These automated collection systems have a significant impact in maximizing supply of blood components. With first time donors, who can sometimes represent up to 30% of all blood donors for a given drive, the blood type has not been tested and is not on record. Current protocols may direct that donor for a collection that does not serve the needs of the center on that day or worse, miss an opportunity to maximize yield from a highly needed blood type such as O negative, the universal donor. The decision to direct an O negative donor to red cell apheresis which yields twice the amount of red blood cells as a whole blood donation is an important one. Conversely, if an AB negative individual donates a traditional unit of whole blood, there is a chance that the red cells will be discarded and only the plasma retained increasing waste and cost. The overall value of that donation is limited to that of one unit of plasma. Had that individual been identified as an AB and agreed to donate via plasmapheresis, the yield of plasma could be five times that of the whole blood donation. Given fixed costs of the donation process, the latter scenario makes more practical and economic sense. A tool to quickly determine the blood type of first time donors could help educate them on the medical value of their donation and direct them to the collection method that best meets the blood center s current needs. And while implementing such a tool introduces costs to the donation process, the net gain in desirable collections and a reduction in low demand or low yield collections can far outweigh those costs. For blood centers, the Micronics ABORhCard provides such a tool for identifying the blood type of first time donors. Armed with this information at the time of donation, blood collection staff can determine the type of donation whole blood, red cell apheresis to collect double red cell units, or plasmapheresis that best fits the blood center s current needs. For example: Donors identified as blood type O positive, A positive & B positive can be directed to traditional whole blood draw ABORhCard Applications and Performance Studies 3

4 Donors identified as blood type O negative, A negative & B negative can be directed to red cell apheresis (double red cell collection) to maximize yield of red cells Donors identified as blood type AB (positive or negative) can be directed to plasmapheresis ValUCalc Economic Impact of Pretesting First Time Donors First time donors represent the largest opportunity to obtain the right product from the right donor at the right time. The adoption of apheresis technology in the U.S. continues to grow each year more than 12% of all RBC collections in 2011 were done by apheresis compared to approximately 2% in In periods of declining donations, such as the 9.1% drop seen in 2011 over 2008, the drive to improve efficiencies and increase product yield is even greater 6. Pretesting of first time donors and using apheresis technology are two highly useful measures to reach supply goals. To demonstrate the potential financial impact, Micronics has created the ABORhCard ValUCalc tool. This tool may be used to estimate the potential net gain realized after directing pre-typed first time donors to the appropriate collection. Input for the tool includes, but is not limited to The cost to the blood center for pre-typing first time donors with the Micronics ABORhCard The average dollar amount paid by hospitals for blood component units The center s algorithms for directing donors based on blood type ABORhCard ValUCalc tm Blood Center Information Blood Center 100 Need Plasma Street Give Blood, USA *% New Donors 30.0% The output of the model is a dollar value net gain from increasing the number of desired components produced and reducing waste from low demand components collected. Using ValUCalc, a typical report could reveal the following: A blood center that collects 100,000 units of blood per year and has 30% new donors would realize an additional $370,000 dollars of additional revenue (this includes the cost of purchasing the ABORhCard) from the optimized collection of 2x RBCs from O negative donors and reduction of unused RBCs from AB donors. ABORhCard For Use in Other Settings As an educational and informational tool, the Micronics ABORhCard may be used in a variety of settings. The card s simple procedure and safe design make it an ideal choice for blood typing needs in non-laboratory settings. In addition, the operational versatility, room temperature storage and long shelf life make it ideal for outdoor and mobile environments. Medical and Nursing Schools and other Health related courses/classes Educational tool used for hands on blood type training ABORhCard Applications and Performance Studies 4

5 Physician Office to provide blood type information to the patient during office visit For student registration and enrollment at institutions of higher learning To provide blood type information for police and other para-military groups At Health Fairs (work place, community and schools) used with other point of care tests to provide useful health and wellness information Blood Donor Recruitment/Donor Mining Events used at local schools or other donor sites to type prospective donors as a recruitment tool for future donations Military Use to verify/confirm ID tag information for blood type Mobile Blood Drives where storage space and power are limited Consular Services where blood type is required in re-issuing national ID cards or drivers licenses. Especially useful in consular outreach programs ABORhCard Principles/Procedure The ABORhCard contains murine monoclonal antibodies, Anti-A, Anti-B, and Anti-D (Rh) pre-dispensed into channels in the card. These antibodies determine the presence or absence of human blood group antigens A, B and D (Rh) on red cells collected in a capillary whole blood sample. A tube of rehydration buffer is included in the test kit packaging. The user dispenses the buffer into the Buffer well on the card (Figures 1a and 1b), from which the buffer flows directly into the channels and re-hydrates the antibodies. The antibody rehydration is visually confirmed by the user, who will see blue, red-orange or green colors, respectively, in the A, B and D Verification windows (Figure 2). Figure 1a Figure 1b Figure 2 Then using the alcohol wipe, lancet and capillary pipet provided, a finger stick blood sample is collected and dispensed into the card s Blood well (Figures 3a and 3b). Figure 3a Figure 3b A second verification step occurs where blood is confirmed to have reached the verification windows. At this point, the reaction is ready to start. Using the on board Pump, the blood and reagents are ABORhCard Applications and Performance Studies 5

6 drawn into Results windows where the mixture in each window may be observed for agglutination or lack thereof. The resultant ABO blood type and Rh factor status are indicated by the location of agglutination in the respective Blood Type windows. Result Interpretation Agglutination (the visible clumping of red blood cells with a particular antibody) indicates the presence of the specific corresponding antigen on the red blood cells being tested. The absence of agglutination (a smooth stream of dilute red blood cells) indicates that the cells are negative for the specific corresponding antigen. Representative agglutination patterns are depicted below in Figure 4. Figure 4 Blood Type (ABO & Rh) Blood Type (ABO & Rh) O Positive B Positive O Negative B Negative A Positive AB Positive A Negative AB Negative Performance Studies ABORhCard Verification Studies with EDTA Samples and CPD Segments A study of 267 anonymized, blinded, EDTA anticoagulated blood samples and 101 CPD segments were tested on the ABORhCard. The initial percent agreement with the unblinded blood type in the verification study was 97.6% and the results are summarized below (Table 2). Table 2: Summary of Verification Studies Sample # ABORhCard Initial Agreement ABORhCard Confirmed Agreement % Confirmed Agreement % ABORhCard Applications and Performance Studies 6

7 Reproducibility Studies Reproducibility studies were performed using a blinded proficiency panel at each of the three clinical trial sites. Product training was provided to all sites prior to reproducibility testing. A total of 27 users were trained. Three four-member panels (EDTA anticoagulated vacutainer samples) of random ABO/Rh blood types were tested in duplicate on three separate days by each trained user, one panel each day. The overall concordance rate of the proficiency sample test results with the correct blood type was 98.7%. Nine (9) of 690 proficiency sample tests were incorrectly typed on initial testing; all 9 were correctly typed upon blinded, repeat testing. Clinical Study Results A clinical study was conducted on a total of 1700 volunteers at three field trial sites selected to capture a diverse sample population, facility and environmental demographics. Testing with the ABORhCard was done with fresh capillary blood collected by finger stick. These results were then compared to sample results generated by each site using its test of record, and agreement/disagreement of ABO and Rh results was recorded. Only de-identified samples that enabled routine laboratory testing using the licensed test of record for the trial site and repeat reference testing were included in the study. The study results are presented below (Table 3): Table 3: Summary of ABORhCard Clinical Test Results # Samples/ Cards # ABO Discords ABO% Agreement # Rh Discords Rh% Agreement % Overall Card Agreement Total Results % % 97.12% 95% Confidence Intervals 97.30% % 98.15% % 96.25% % Limitations The Anti-D monoclonal antibody used in the ABORhCard does not recognize partial D category VI cells (DVI). DVI cells occur in approximately 1 in 5000 Rh positive individuals. The ABORhCard does not contain an isoagglutinin control. Therefore, a Blood Type result of AB Positive may be as a result of the presence of isoagglutinins in the blood sample and cannot be considered a valid test. Three percent of the population is AB Positive in the U.S. (See Table 1). The performance of the ABORhCard has not been established for use with lipemic blood samples. ABORhCard Applications and Performance Studies 7

8 References 1 History of Blood Transfusion, American Red Cross website, accessed September 2013, learn-about-blood/history-blood-transfusion. 2 The Structure and Function of the Rh Antigen Complex, Westoff, C., Seminars in Hematology, January 2007, 3 Blood Types in the U.S, accessed October 2013, facts on blood transfusion, WHO website, accessed September 2013, transfusion/en. 5, 6, 7 The 2011 National Blood Collection and Utilization Survey Report, U. S. Department of Health and Human Services, Whitaker, B., et. al. pages 1-2. Micronics, Inc th Avenue NE Redmond, WA Fax: info@micronics.net support@micronics.net FDA 510(k) cleared for educational and informational purposes All rights reserved. ABORhCard is a registered trademark of Micronics, Inc A