Transfusion Medicine, 2011, 21, 63–64 doi: 10.1111/j.1365-3148.2010.01038.x LETTER TO THE EDITOR Reply to: prevalence of immediate vasovagal reaction in blood donors visiting two blood banks of Karachi Dear Sir, We read with interest the paper by Rohra et al. (2010) titled ‘Prevalence of immediate vasovagal reaction in blood donors visiting two blood banks of Karachi’ that reported some interesting facts about the donor reactions in the whole blood donors. Though the frequency of vasovagal reaction (VVR) in whole blood donors differs across the nations, yet 13·5% of blood donors experiencing one or more symptoms of immediate VVR, as found in this study, is still quite high. There is not much cultural difference between India and Pakistan and blood donor population is almost similar in both the countries. However, our experience of VVR in blood donors is at variance with the present study. Our hospital is a tertiary care centre with a present annual collection of around 25 000 blood units. Tondon et al. (2008) from our hospital reported the rate of donor reaction to be 1·6% in their study. Furthermore, during the last 2 years, only 1040 (1·8%) donors out of 57 603 donors were observed to have symptoms of VVR at our hospital (unpublished data). The rate of VVR in our blood donors was almost similar to other studies published across the world (Zervou et al., 2005; Crocco et al., 2007; Tomasulo et al., 2009). Authors have also stated that there are no clear cut guidelines regarding the blood donation criteria in Pakistan, and they are collecting 500 mL blood from every donor irrespective of their body weight and blood volume. Council of Europe (2007) guidelines suggest that no more than 13% of the estimated blood volume should be collected during one whole blood dona- tion. According to the American Association of Blood Banks (AABB, 2008) standards, the maximum amount of whole blood (including sampling tubes) that can be collected from a donor is 10·5 mL kg -1 . As per our guidelines (NACO, 2007), we collect 350 mL from a donor weighing less than 55 kg and 450 mL from a donor who weighs more than 55 kg. A study from Pakistan (Salamat, 2007) has suggested that the collected Correspondence: Dr Nitin Agarwal, MD, Department of Transfusion Medicine, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India. Tel.: +91 522 2494885; fax: +91 522 2668017; e-mail: nuts medico@rediffmail.com; nitin aggy@yahoo.com blood volume from a blood donor in Pakistan should be 450 ± 45 mL. Though most of the studies from all over the world have shown a significant relationship with age, weight, gender and previous donation status (Newman, 2003; Kamel et al., 2010), surprisingly, this study fails to recognise any association of these risk factors with donor reaction rate. Analysis of data collected from the digi- tal database of our blood bank for the previous 2 years clearly shows significant association with age, weight, first donation and long waiting period before donation. Failure to recognise any of these risk factors in this study may be attributed to the very small study population as compared to other studies. In addition to this, authors have not given the demographic characteristics of sub- jects who had VVR; for example, they have reported that around 35% of the donors were below 25 years of age, but how many of these young donors experienced VVR is not clear. We suggest that in the absence of a national crite- rion for donation, it would be a prudent strategy to follow some established guidelines like the AABB or European Council. The other possible factors, such as uncomfortable environment and absence of donor coun- selling, which are not donor specific may be related to such an increased rate of VVR in the present study, which must also be looked into. This is important for any centre as reduction in donor adverse reaction rate will help in improving donor retention and maintaining better blood donor pool. N. Agarwal, D. Sachan & A. Verma Department of Transfusion Medicine, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India REFERENCES AABB. (2008) Standards for Blood Banks and Transfusion Services (25th edn). American Association of Blood Banks, Bethesda, MD. Council of Europe. (2007) Guide to Preparation, Use and Quality Assurance of Blood Components (13th edn). Council of Europe Publishing, Strasbourg, France. Crocco, A. & D’Elia, D. (2007) Adverse reactions during voluntary donation of blood and/or blood components.  2010 The Authors Transfusion Medicine  2010 British Blood Transfusion Society 63