Katja van den Hurk works as a senior epidemiologist at the department of Donor Studies at Sanquin Blood Supply. Her main research topics are Donor characteristics and Donor health. Sanquin, by law the only blood bank in the Netherlands, has an extremely loyal donor population of about 2.5% of the Dutch population, that make approximately 800.000 donations per year. In the Netherlands the blood supply is dependent on voluntary non-remunerated donors.
Sanquin has organized the first European Conference on Donor Health and Management, which took place on September 3-5, 2014. What were the highlights?
“Meeting 250 enthusiastic professionals in a relatively small work field is thrilling. Current regulations around blood donation are mainly based on expert opinions instead of evidence based science. The conference program balanced between science and daily blood bank practice. Managers, recruitment professionals and scientists came together and exchanged information. One example of an interesting presentation was by Olga Flinter and Stephen Cousins. They showed how the Irish blood bank fine tunes the blood donor management by using long term and short term prediction models. We presented our own large cohort studies and saw interesting cohort data from Danish and British research groups. You could really see the field is upcoming.”
How healthy is the Dutch donor?
“The donor health check, which precedes donations, already selects for a healthy population. That makes the Dutch donor population healthier than the average Dutch population. Besides, donating blood (in the Netherlands) is pro-social behaviour, since donors are not paid for donations. This might lead to selection of a more health-conscious subgroup of the average population. ”
How do you study the effect of donation on donor health?
“The so called healthy donor effect complicates comparing donor health with the health of the general population. So we try to compare different groups within the donor population. For instance new donors versus donors with a long donation career. Or donors who donate frequently to those who donate less frequent. There are several factors that influence donation frequency independent of health-related factors, such as residence. Donors living in remote parts of the country donate blood at the mobile blood center, which travels the country with a relatively low frequency. However, the health of a rural population may be different than that of an urban population. We try to correct for factors like this as much as possible.”
Approximately 5% of the donors is deferred at the collection center because of low Hemoglobin (Hb). Does that imply they are anemic?
“No, the cut-off that is handled for Hb is well above the lower limit for normal Hb concentration, in order to protect the donor. However, we cannot exclude that donors are iron-deficient with a normal Hb. Hb is only an indirect marker for body iron, so it is possible that Hb levels are maintained before donating, while iron stores are depleted and therefore insufficient to restore Hb levels after a donation. There was a lot of discussion on this topic at the conference. Shouldn’t we screen for ferritin, a marker for iron stores? In the Netherlands we use ferritin testing in research only, while for instance in Scandinavia ferritin testing is already becoming part of the blood bank routine. New methods to prevent iron depletion in donors have to be proven safe and cost-efficient before these are implemented.”
Could you prevent deferral by predicting Hb?
“We aim to minimize donor deferral, as it is disappointing and time-consuming for both donor and blood bank, and an important reason of donor lapse. Donors each have personal characteristics that may determine their capability to recover from blood donations. Donors may vary in how quickly they restore Hb levels, supplement red blood cells and in their efficiency of iron uptake from food. We have recently started a study (Donor InSight (DIS)-III) in 3000 donors in which we will investigate genetic determinants in relation to declining versus stable Hb levels in repeat donors. We’ll search for a gene profile that is predictive for Hb decline so to determine the optimal donation interval for each future donor. Combining this test with a genetic array for blood types could be a cost–effective way to implement the results. In the future we hope to be able to personalize donation intervals for each donor, to prevent deferrals and keep the donor healthy.”
Donor InSight is a very large cohort study. What will you do with all the data?
“The study is generating big data that we like to share with others. We cordially invite interested researchers to contact us in order to find out if we can help them answer their research questions. Two questionnaire rounds, DIS-I in 2007-2009 (n=31,338) and DIS-II in 2012-2013 (n=34,823, of whom 22,132 also participated in DIS-I), were completed to gain more insight into characteristics of donors, their motivations and health. DIS data can (routinely) be linked to the donor database, with details on all donations, containing donor screening results including the donor health questionnaire answers, blood pressure and haemoglobin measurements. Potential research questions to be addressed with these data are not limited to blood donation-related issues. At Sanquin we have for example looked into associations between outdoor temperature and blood pressure. It is a well-known fact that mortality among elderly is higher in extremely cold and hot weather. Before each donation we measure blood pressure while the temperature is registered at a nearby weather station. We correlated the two, and found that blood pressure was lower at higher temperatures, especially at high age and the associations were significantly stronger at higher temperatures. Because the Dutch climate is temperate and the donor population is relatively healthy, we think that effects of more extreme temperatures in more vulnerable populations might be stronger.”
Are you blood donor yourself?
“Yes, I have become a donor too. I was a little anxious at first, because I usually have a rather low blood pressure. But I wanted to have a better understanding of what blood donation is about and what donors experience. And I must admit, it feels better than expected. The donor assistants did pamper me with soup and allowed me extra time to lie down. Before donations I drink half a liter of water. It has been shown that this helps to prevent vasovagal reactions after blood donation. In fact I hardly notice anything after a donation.”