A PROSPECTIVE STUDY OF FACTORS RELATED TO PLATELET YIELD AMONG DONORS UNDERGOING PLATELETPHERSIS

Irfan khan, Aleem Jan, Arshad Hassan Siddique, Arouj-bin-rashid, Zakir Bhat, Naira Firdous Zargar , Sehar kenu and Jaiparam singh wazir. 1. Senior Resident, Department of Transfusion Medicine, SKIMS, Srinagar, Jammu and Kashmir, India. 2. Additional Professor, Pediatric Hematology and Head Department of Blood Transfusion and Immunohematology, SKIMS, Srinagar, Jammu and Kashmir, India. 3. Senior Resident, Department of Transfusion Medicine, SKIMS, Srinagar, Jammu and Kashmir, India. 4. Scholars, Department of Transfusion Medicine, SKIMS, Srinagar,Jammu and Kashmir, India. 5. Junior Resident, Department of Transfusion Medicine, SKIMS, Srinagar, Jammu and Kashmir,India. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


(3), 1051-1054
1052 Plateletpheresis (apherisis= to remove ) is a procedure designed to collect large number of platelets from single donor thereby giving more consistent product (9). As per guidelines of American association of blood banks plateletpheresis (Single Donor Platelets) unit must have platelet count of 3x 10 11 which in turn raises platelet count by 30,000-60,000 per micro litre and is equivalent to 4-6 units of random platelet concentrates (10).Compared to whole blood donation, apheresis has advantages for the donor, such as there is lesser loss of red blood cells. However, apheresis can also lead to specific adverse events such as citrate toxicity or, for single needle devices, extracorporeal circulation reactions (11)(12)(13).Platelet transfusion success depends on rational use of platelet components and on the quality of the component. Platelet recovery in a patient is influenced by the transfused dose of platelets which in turn is dependent on the platelet yield. (14) The possibility of obtaining higher platelet yields has important clinical implications: it reduces frequency of platelet transfusions and number of donor exposures with important consequent clinical and economic advantages. (15,16)

Material and Methods:-
This is a prospective case study conducted from August 2015 to December 2016 at teritary care centre in North India. A total of 360 healthy donors comprising of 359 men and 1 woman with mean age of 41.8 years were selected from plateletpheresis donor registration. With the exception of the donation interval, the requirements for apheresis and whole blood donation are the same. Apheresis donors must meet the requirements for whole blood donation and additionally satisfy criteria that are particular to the selected apheresis. Donors that were less than 18 years and more than 60 years, or were on any medical treatment 7 days prior to the procedure were excluded in this study.Blood samples were collected from donors before and after apheresis procedure.Informed consent was obtained from all donors. Donor screening is required to ensure a safe transfusion for the recipient. Prospective donors must complete several steps before actual platelet donations, including physical examination, a donor history questionnaire, and testing for transmissible diseases. The American Association of Blood Banks (AABB) recommends that prospective donors receive physical examinations including an assessment of weight: hemoglobin, hematocrit, ABO and Rh typing: and inspection for marks from intravenous drug use. Tests are performed for the presence of syphilis, human immunodeficiency virus (anti-HIV-1/2 and HIV-1 RNA), hepatitis C virus (anti-HCV and HCV RNA), hepatitis B virus (HBsAg and anti-HBc), Further, the platelet counts of plateletpheresis donors must be >150×103 per μl [32]. Individuals can donate 3 days after ingesting aspirin-related medications.
Apheresis was performed using Trima (Gambro BCT, Lakewood, CO).Acid-citrate-dextrose formula was used as anticoagulant during procedures according to the manufacture's recommendations.
All procedures were completed successfully with peripheral venous access . Cubital vein was used for access. All procedures done were single needle. The procedure was continuous and automated. The blood pump speed was set at of 60-80 ml/min . Blood pressure (BP) and pulse were monitored at frequent intervals during the sessions and donors were closely observed for development of any complications and overall status.

Results:-
The results obtained are tabulated below : The maximum number of patients had hemoglobin in the range of 14-15 g/dl and 15-16 g/dl, depicting the donors overall had been derived from healthy population. Only where donor constraint was an issue , selection was done in the Hb range 12-13 g/dl and > 17 g/dl. The haematocrit of the donor population were between 40-45% in maximum number of donors.  The platelet yield was between 2-3x10 11 in maximum number of donors. The side effects were less observed in the procedure done. The most common reaction had been citrate reaction followed by hematoma formation at vascular access site.

Discussion:-
Various studies have shown that transfusion of high platelet doses could reduce number of platelet concentrates required by thrombocytopenic patients even in patients with adverse clinical factors in which refractoriness to transfusion is common (17,18).Nevertheless, there are very few studies related to donor clinical and laboratory factors that may influence number of platelet yield (4,19). Identification of these factors would allow for better selection of donors resulting in higher platelet yield and consequently a lower number of donor exposures to the patients. Instruments which collect SDP are programmed to calculate the yield from the donor's haematocrit, platelet count, height and weight.
In our study, the mean pre-donation platelet count was 2.29 ± 0.43 x10 5 /μL and the mean platelet yield was 2.86 ± 0.52 x10 11 . A direct linear correlation was obtained between the pre-donation platelet count and the platelet yield (r = 0.284, p<0.01). Ravi et al (20), found the mean pre-donation platelet count was 2.69± 0.65 X 10 5 /μL and the mean platelet yield was 3.16 ± 0.62 X 10 11 . A good direct linear correlation was obtained between the pre-donation platelet count and the platelet yield (r = 0.284,p<0.01). Chaudary R et al, reported that out of 94 plateletpheresis procedures, the mean platelet yield was 3.65± 0.80 x10 11 when the predonation platelet count was <3 x 10 5 /μL, while the mean yield was 2.5 ± 0.59 x 10 11 when the pre-donation platelet count was >2 x 10 5 /μL. They also observed a direct relationship between platelet count and platelet yield (r=0.50, p<0.001) (21). In a study, 2708 plateletpheresis procedures having a mean pre -donation platelet count of 2.37 ± 49 x 10 5 /μL resulted in a platelet product with mean yield of 4.24 ± 1.1 x 1011. A direct linear correlation was observed with all the procedures (4). In a study (22) donor pre-donation platelet count was found to positively correlate with the platelet yield (r = 0.51, p<0.001). A direct positive correlation was also observed in another study17 (r = 0.512) (23). Our observations were similar.
In our study, 204 donors gave a platelet yield of more than 3 x10 11 per unit and thus 56.6% of our platelet yield met AABB guidelines. As per European guidelines 324 of our donors i.e.,93% had a platelet yield of > 2x 10 11 (20). Chaudhary et al., found only 41.5% of the SDPs met AABB guidelines (19).
Our study showed negative correlation between the donor age and platelet yield (r = -0.329, p<0.01). Das SS et al., has showed a significant negative correlation between the donor age and platelet yield (r = -0.229, p<0.01) but no such observation was reported in another study (21).The decreasing platelet yield with increasing age found in our study may be explained the physiological decrease that occurs to platelet count with increasing age. (22) We found a positive correlation between platelet yield and either haemoglobin (r = 0.063) or haematocrit (r = 0.021).While as positive correlation between platelet yield and donor haemoglobin and haematocrit have been found in some studies (25,17). No correlation was observed between the haemoglobin concentration and platelet yield in another study. They reported that donors with a haemoglobin levels of 16 g/dL or more gave a comparatively lower platelet yield. This could be related to the higher plasma volume processed in donors with low haemoglobin concentrationthereby giving a higher platelet yield (19).
Furthermore, a positive correlation between BMI and platelet yield (r = 0.268, p<0.01). Similar observations were reported is another study (18) where BMI correlated consistently with a good platelet yield. But, in another study (19) where the quality of SDP in relation to low weight (40.8-49.9 Kg) of the donors was studied, donor weight was not found to have any effect on platelet yield. Since there was only one female donor, we are not able to calculate the correlation between the platelet yield and gender. In a study (21) it was found that gender also influences platelet yield and women had higher yields. This was possibly because there is a higher prevalence of iron deficiency among women with consequent increase in platelet count; hormonal influence could also play a role.