A novel approach to detect test-seeking behaviour in the blood donor population: making the invisible visible.
OBJECTIVE
Individuals may donate blood in order to determine their infection status after exposure to an increased infection risk. Such test-seeking behaviour decreases transfusion safety. Instances of test seeking are difficult to substantiate as donors are unlikely to admit to such behaviour. However, manifestation in a population of repeat donors may be determined using statistical inference.


METHODS
Test-seeking donors would be highly motivated to donate following infection risk, influencing the timing of their donation. Donation intervals within 2005-2014 of all Dutch blood donors who acquired syphilis (N = 50), HIV (N = 13), HTLV (N = 4) or HCV (N = 2) were compared to donation intervals of uninfected blood donors (N = 7 327 836) using the Anderson-Darling test. We adjusted for length bias as well as for age, gender and donation type of the infected. Additionally, the power of the proposed method was investigated by simulation.


RESULTS
Among the Dutch donors who acquired infection, we found only a non-significant overrepresentation of short donation intervals (P = 0·54). However, we show by simulation that both relatively short and long donation intervals among infected donors can reveal test seeking. The power of the method is >90% if among 69 infected donors >35 (51%) are test seeking, or if among 320 infected donors >90 (30%) are test seeking.


CONCLUSIONS
We show how statistical analysis may be used to reveal the extent of test seeking in repeat blood donor populations. In the Dutch setting, indications for test-seeking behaviour were not statistically significant. This may, however, be due to the low number of infected individuals.
Transfusion Technology Assessment Unit, Sanquin Research, Amsterdam, the Netherlands. A.deVos@Sanquin.nl.
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de Vos
Department of Blood-Borne Infections, Sanquin Research, Amsterdam, the Netherlands.
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Lieshout-Krikke
Department of Blood-Borne Infections, Sanquin Research, Amsterdam, the Netherlands.
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Slot
Institute of Mathematics, Astrophysics and Particle Physics, Radboud University, Nijmegen, the Netherlands.
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Cator
Transfusion Technology Assessment Unit, Sanquin Research, Amsterdam, the Netherlands. m.p.janssen@umcutrecht.nl.|Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, the Netherlands. m.p.janssen@umcutrecht.nl.
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Janssen
D000328:Adult; D001519:Behavior; D001782:Blood Donors / Q000523:psychology / Q000706:statistics & numerical data*; D005260:Female; D015658:HIV Infections / Q000175:diagnosis; D006526:Hepatitis C / Q000175:diagnosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009042:Motivation; D013587:Syphilis / Q000175:diagnosis
donation intervals; repeat donors; test-seeking behaviour