Determination in vivo viability of a transfused platelet product by corrected count increment and percentage platelet response

Determination in vivo viability of a transfused platelet product by corrected count increment and percentage platelet response

Nancy Wanjiru Thuku^1,&, Kibet Shikuku², Amos Mbugua³

 

¹MSc student at Jomo Kenyatta University of Agriculture and Technology, Head of Haematology and Blood Transfusion Science Section at Mbagathi District Hospital, Nairobi, Kenya, ²Lecturer at University of Nairobi, College of Health Sciences Department of Human Pathology, Haematology and Blood Transfusion Unit, Nairobi, Kenya, ³Lecturer at Jomo Kenyatta University of Agriculture and Technology College of Health Sciences, Nairobi, Kenya

 

 

^&Corresponding author
Nancy Wanjiru Thuku, MSc student at Jomo Kenyatta University of Agriculture and Technology, Head of Haematology and Blood Transfusion Science Section at Mbagathi District Hospital, Nairobi, Kenya

 

 

 

 

Platelets concentrates are mainly used in thrombocytopenic patients mostly commonly as a result of myelo-supplessive therapy. Increased consumption as in disseminated intravascular coagulopathy (DIC), a plastic anaemia due to qualitative defects in Bernard Solier syndrome or in quantitative defects in decreased platelets counts which is seen in myeleosuppressive drugs like chemotherapy [1]. A normal platelets count ranges from 150,000-450,000 platelets per microliter of blood and values outside this range do not indicate disease. Platelets that need emergency treatment are a count below 50,000 per microliter [2] but at Kenyatta National Hospital, majority of recipients are considered emergency transfusion of platelet concentrates at a count of 20×109 platelets in the circulation. Thrombocytopenia correlates with bleeding complications, guidelines advise to institute a platelet transfusion policy to prevent and treat bleeding complications.Studies concerning platelet concentrate transfusions conducted between the early eighties until the late nineties mainly investigated product modifications to reduce adverse reactions, such as (non)-immunological refractoriness and febrile transfusion reactions. It was only in the last decade that clinical efficacy became an issue, and more to blood bankers than to clinicians [3].

 

Modifications have been performed to improve the safety profile are typically characterised by removing one or more components after blood donation. With regard to efficacy as an endpoint for platelet transfusion in recent years have shown increasing doubts and problems with the commonly used endpoints: corrected count increments and bleeding. The corrected count increment (CCI) is a ratio correcting for a measure of blood volume and the number of transfused platelets. This method has been challenged by several authors in the field with as main arguments a bias in favour of a preparation technique with fewer platelets combined without adequately estimated blood volume and doubts regarding the usefulness of the CCI as a surrogate outcome measure as it does not predict the clinical outcome bleeding [4]. The methods for evaluation of in vivo viability (therapeutic efficacy) of platelets are corrected count increment and percentage platelet recovery (PPR) [5]. There is a constant demand of platelet concentrates in KNH, as a referral Hospital, in the management of different conditions. While platelet concentrates are highly perishable, costly and needs a thorough investigation in the point of collection, separation, storage, and selecting compatible recipient, administration requiring maximum quality efficiency and safety. This study sought to investigate the in vivo viability of a transfused platelet product. The objective of this study was therefore to determine in vivo viability of a transfused platelet product by corrected count increment and percentage platelet response.

 

 

The study was conducted in Kenyatta National Hospital Blood Transfusion Unit. In addition preparation of platelet concentrates was done at Kenya National Blood Transfusion Services which is beside Kenyatta National Hospital. This was a descriptive analysis study in determination of platelet counts in platelet concentrates and effectiveness of platelets after transfusion at Kenyatta National Hospital Blood Transfusion Unit. A total of 384 platelet concentrates for assessment of quality of platelet concentrates was included after fulfilling the inclusion criteria which was systematically selected [6]. During study period, 123 recipients of the platelet concentrates (aged between 1-60 years) was recruited for determination of in vivo viability of transfused platelet products. The study was conducted out between July and December 2016. The sample size for the study was calculated using the formula; n=Z²P (1-P)/d² [7]. The sample size calculated was 246. The sampling method was systemic sampling which was quick and easy way to obtain unbiased data and is less expensive

 

Corrected count increment: CCI: apheresis platelet concentrates = (Post-platelet count-Pre-platelet count)(BSA) platelets transfused (x10⁹) CCI >Body surface area (M2) Example: a woman transfused with SDP (4 x 10⁹). Platelet count pre=8, post=42. BSA=1.5 M²

 

Percentage Platelet Recovery (PPR): Percent Predicted Count (PPC) =No. platelets transfused x 0.67 x .001 blood volume (mL) Percent Platelet Recovery (PPR) = (post-platelet - pre-platelet count)x 100% percent predicted count Permission of carrying out research was acquired from the KNH-UON ERC. In addition written informed consent/assent was obtained from parents/guardians willing to participate by the clinician following a detailed explanation of the study to them. In case of an illiterate parent/guardian, a literate witness who did not have any connection in the study, signed. It is only after the patient/parent/guardian had signed the consent/assent did the study began.

 

Laboratory procedures: two milliters of whole blood was collected following sample collection guidelines as described by Kenyatta Hospital Haematology Laboratory standard operating procedure (S0P). The samples were preserved using ethylene diamine tetra acetic acid EDTA and transported to Haematology Laboratory for analysis. Laboratory analysis was done in Haematology Laboratory, Kenyatta National Hospital. The standard operating procedure (SOP) for preparation of platelet concentrates as described by KNBTS was used. The in vivo viability of platelets product after transfusion was determined by the percentage of the transfused platelets recovered in the recipient's circulation immediately after transfusion (% recovery) and by the life span in circulation of these recovered platelets (survival). Two methods were used in this study for platelet survival. These are corrected count increment (CCI) and percentage platelet response (PPR). Pre and post blood from recipients who have been transfused with platelet concentrates were analysed and both corrected count increment and percentage recovery (PPR) were calculated after 1-hour and 20-hours. This was evaluating platelet transfusion response. The measurements were calculated as follows: CCI= (Post-platelet count-Pre-platelet count) (BSA (Body Surface Area) in M²) /platelet transfused ×10⁹ Normal values ≥ 7500 at 1 hour and ≥ 5000 at 20 hours. PPR = (post platelet counts-pre platelet counts) ×100%/percentage response counts Normal values of PPR is ≥ 60% at 1-hour and ≥ 30% at 20-hours. Quality control was ascertained using AcT Cell Control Plus from Phillips Healthcare Technologies Limited (these are commercial cells control).

 

Data management and analysis: all collected data were entered into computer database in Microsoft excel (Ms-excel) computer application. To avoid loss, back up of the data was burned on compact discs, external hard disc and pen drives (flash discs). Validation and cleaning of the data was done during data collection and entry and later exported to and analysed by Statistical Package for Social Sciences (SPSS) version 20. Data analysis was conducted using descriptive, Statistical Package for Social Sciences, (SPSS) software. After being entered into MS-EXCEL, the number and percentage distribution was calculated. The number and percentage distribution was calculated and the student t-test was used to test significance at P ≤ 0.05. Descriptive means, frequencies and percentages was used to describe and summarizes data. Tables, pie charts and graphs were used to present results.

 

 

Of the transfused patients 72% were female while 28% were males. After platelets concentrates quality parameters assessment only 65% (246) were fit for platelets transfusion and 35% were unacceptable (Table 1). In this study the majority of patients transfused with platelets concentrates 75% male and 80% female, after calculating their percentage platelets response were ≥ 60% at one hour. After 20 hrs it's only a few of them 18% male and 25% female had PPR ≥ 30% indicating refractoriness on the majority of patients. The causal agent of refractoriness could be immune or non-immune. In this study the evaluation of platelet transfusion was done using corrected count increment (CCI). This is in vivo measurement platelet survival which requires a 1-24 hour post-platelet count. In addition, the 1-hour post transfusion CCI was 72% ≥ 7500 in male recipients while female recipients had 69% ≥ 7500 which was normal but after 20-hour post transfusion the CCI was 30% ≥ 5000 in male recipients while 25% ≥ 5000 was seen in female recipients. This scenario was not a successful transfusion increment and was an indication of refractoriness on the majority of recipients (Table 2).

 

 

The in vivo viability of the platelet products was done from the calculation as corrected count increment (CCI) and in this study, 72% of male recipients showed a CCI ≥ 7500 after 1-hour transfusion and 30% CCI≥ 5000 after 20-hour while the 69% of the female recipients had a CCI ≥ 7500 after 1-hour and 25% had a CCI ≥ 5000 after 20-hour. After transfusion of platelets concentrates on patients, 75% male and 80% female had percentage platelets response › 60% but after 20 hrs only 18% of male and 25% of female had ≥ 30% PPR indicating low viability of transfused platelets products (Figure 1). This reflects a very low viability of platelet product according to British committee for standards in haematology criteria resulting to successful transfusion for CCI. Failure of the majority of these recipients to achieve the expected platelet increment after 20-hours could be due to alloimmunization to HLA class 1 antigen or HPA to HLA class 1 antigen or HPA.

 

 

The findings of this study suggest apheresis platelets transfusion need to be introduced at KNH and use of leukoreduction performed on the platelet concentrates which are prepared within the Hospital. With such rate of refractoriness, additional tests to confirm the real cause of unviability of platelets in the patients need to be performed. These tests include bone marrow examination, polymerase chain reaction, immunohistochemistry and antibody screening test for alloimmunization, passive immunity and auto antibodies. Antibody elusion tests must be included for confirmation antibodies. In the process of separation of platelet product (opts press release), one should be carefully not to allow White blood cells which result to HLA antibodies to recipient circulation after transfusion. KNH should ensure those recipients with low profile of viability of platelet counts to perform evaluation of pattern of refractoriness using 1-hour and 20-hour pre and post transfusion levels of platelets viability, perform cross- match compatibility and HLA- compatibility testing and last but not least to recommend future report of usage of transfused platelets concentrates to these recipients.

 

 

The authors declare no competing interest.

 

 

Nancy Wanjiru Thuku BSc Medical Laboratory Science; primary author; conception or design of the work; data collection; data analysis and interpretation; drafting the article Amos Mbugua PhD, He is the principal supervisor and he has immensely contributed towards reviewing and encompassing directions as well motivational and dynamic assistance and played the following roles; critical revision of the article; final approval of the version to be published Kibet Shikuku MBCh, MMED (human pathology); he is a clinical supervisor at Kenyatta national hospital and was a key to this journal in the following ways; he is a clinical supervisor; clinical consultant and supervisor.

 

 

I would like to acknowledge my principal supervisor Dr Amos Mbugua, PhD for his tireless support and guidance towards this dissertation for without him, would have been difficult. He has contributed significantly to my development and success as my supervisor. his passion, innovativeness, intellect and positive outlook have encouraged me to maintain high standards of performance, to develop creative solutions and to assist me with overcoming the challenges of scientific research. He has provided me with the analytical and conceptual tools to complete my master degree but he has also had a profound influence on both my personal growth and professional pursuits. I also acknowledge my second supervisor Dr Kibet Shikuku MBCh, MMED (Human Pathology), for his encouragement and motivation. I am indebted to his voice of reason and sense of humor. I am also extremely fortunate to have a caring, approachable and supportive committee, who have advised and mentored me far beyond their required roles. I also acknowledge Gabriel of KEMRI, Aglean Chelimo the Head of BTU Kenyatta National Hospital and also Agnes Njogu Head of Heamatology section and all the staff at Kenyatta National Hospital for their cooperation, guidance and humble time they gave me during data collection at their hospital setup. Many thanks to all my colleagues for their support and contributions towards this dissertation. My special gratitude and thanks goes to all who contributed to this study and making it a success. I would like to end with a motivational quote that graduate students should remind themselves when research gets tough. When you come to the end of your rope, tie a knot and hang on. All authors have read and agreed to the final version of this manuscript.

 

 

Table 1: quality parameters of platelet concentrate

Table 2: the in vivo platelets response

Figure 1: platelet in normal and refractoriness recipients

 

 

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