Deferral rate variability in blood donor eligibility assessment

Wim de Kort, Femmeke Prinsze, Glenn Nuboer, Jos Twisk, Eva-Maria Merz

Research output: Contribution to JournalArticleAcademicpeer-review


BACKGROUND: Both donors and the blood bank rely on the result of the donor health interview. However, survey data suggest that substantial variability in deferral rates among interviewers exist. We studied whether variability remained after adjusting for conditional factors.

STUDY DESIGN AND METHODS: The data set included Dutch interview data on whole blood donor visits in 2015, where one of their visits was selected randomly. We applied logistic regression and multilevel regression analyses with the donor visit, with the interviewer representing the levels. We set up four models: 1) all reasons deferral, 2) low-hemoglobin-level deferral, 3) infectious disease risk deferral and 4) other medical reasons deferral.

RESULTS: In total, 138,398 visits were included in the study, of which 60,534 (43.7%) related to male donors. The overall deferral rate for men was 7.91% and for women 12.25%. Deferral rates among interviewers ranged from as low as 1.19% up to 28.8%. Models 2 (low hemoglobin level) and particularly 4 (other medical reasons), for both men and women, showed significant intraclass correlation coefficients, implying considerable deferral rate variability among interviewers. Donor age, the number of previous visits, and the season had relatively large effects. However, explained variances of the logistic regression models were relatively low, ranging from 2.53% to 7.35%.

CONCLUSION: Deferral appears to be a random process, while substantial variability was found among interviewer deferral rates, suggesting that some interviewers are more cautious than others. Our results suggest heuristic and subjective diagnosing to be prevalent. Steps should be taken to improve interview result validity.

Original languageEnglish
Pages (from-to)242-249
Number of pages8
Issue number1
Publication statusPublished - Jan 2019


The authors thank the Medical Donor Affairs Department for their information and help in identifying relevant information on the interview procedure and on interviewer variables, especially Rebecca Broekman-Piets, Mariël Casparie, Berber van Duin, Aimee Kwee, and Mai Macroomy. We also thank Bas Romeijn for his support in searching and retrieving relevant literature. WdK and EM wrote the manuscript and designed the study; FP retrieved and cleaned the data; GN critically analyzed the procedures; JT supported in statistical analyses. All authors critically reviewed the manuscript.

FundersFunder number
Medical Donor Affairs Department


    Dive into the research topics of 'Deferral rate variability in blood donor eligibility assessment'. Together they form a unique fingerprint.

    Cite this