Explainable haemoglobin deferral predictions using machine learning models: Interpretation and consequences for the blood supply

The added value of ferritin levels and genetic markers for the prediction of haemoglobin deferral

BACKGROUND AND OBJECTIVES

On-site haemoglobin deferral for blood donors is sometimes necessary for donor health but demotivating for donors and inefficient for the blood bank. Deferral rates could be reduced by accurately predicting donors' haemoglobin status before they visit the blood bank. Although such predictive models have been published, there is ample room for improvement in predictive performance. We aim to assess the added value of ferritin levels or genetic markers as predictor variables in haemoglobin deferral prediction models.

MATERIALS AND METHODS

Support vector machines with and without this information (the full and reduced model, respectively) are compared in Finland and the Netherlands. Genetic markers are available in the Finnish data and ferritin levels in the Dutch data.

RESULTS

Although there is a clear association between haemoglobin deferral and both ferritin levels and several genetic markers, predictive performance increases only marginally with their inclusion as predictors. The recall of deferrals increases from 68.6% to 69.9% with genetic markers and from 79.7% to 80.0% with ferritin levels included. Subgroup analyses show that the added value of these predictors is higher in specific subgroups, for example, for donors with minor alleles on single-nucleotide polymorphism 17:58358769, recall of deferral increases from 73.3% to 93.3%.

CONCLUSION

Including ferritin levels or genetic markers in haemoglobin deferral prediction models improves predictive performance. The increase in overall performance is small but may be substantial for specific subgroups. We recommend including this information as predictor variables when available, but not to collect it for this purpose only.

An international comparison of haemoglobin deferral prediction models for blood banking

BACKGROUND AND OBJECTIVES

Blood banks use a haemoglobin (Hb) threshold before blood donation to minimize donors' risk of anaemia. Hb prediction models may guide decisions on which donors to invite, and should ideally also be generally applicable, thus in different countries and settings. In this paper, we compare the outcome of various prediction models in different settings and highlight differences and similarities.

MATERIALS AND METHODS

Donation data of repeat donors from the past 5 years of Australia, Belgium, Finland, the Netherlands and South Africa were used to fit five identical prediction models: logistic regression, random forest, support vector machine, linear mixed model and dynamic linear mixed model. Only donors with five or more donation attempts were included to ensure having informative data from all donors. Analyses were performed for men and women separately and outcomes compared.

RESULTS

Within countries and overall, different models perform similarly well. However, there are substantial differences in model performance between countries, and there is a positive association between the deferral rate in a country and the ability to predict donor deferral. Nonetheless, the importance of predictor variables across countries is similar and is highest for the previous Hb level.

CONCLUSION

The limited impact of model architecture and country indicates that all models show similar relationships between the predictor variables and donor deferral. Donor deferral is found to be better predictable in countries with high deferral rates. Therefore, such countries may benefit more from deferral prediction models than those with low deferral rates.

Validity of donor-reported iron supplementation practices obtained at the time of donation

BACKGROUND

Iron supplementation (IS) improves blood donors' iron stores and allows more frequent blood donation. Understanding the accuracy of self-reported IS is helpful for potential application of IS practices to donor eligibility or donation intervals.

METHODS

Successful whole blood and red cell apheresis donors completed a survey at donation on the use of select dietary supplements. Respondents reporting use of either iron pills (IP) or multivitamins (MV) were invited by email to complete a similar follow-up survey 6-8 weeks later and to provide the quantitative iron content of IS by referring the donor to the pill bottle label. Consistency between baseline and follow-up responses was assessed overall and by pill type and demographic variables.

RESULTS

Of 2444 donors answering the baseline survey, 40% (978) reported MV or IP at donation, 354 of whom completed the follow-up survey. A majority of survey respondents (56%-61%) reported taking iron across the two surveys, and 21%-24% took MV but were uncertain if their pills contained iron. Of 215 reporting IS at baseline, overall concordance at follow-up was 68% and was higher for donors who were female, ≥50-years old, and taking iron as an iron pill rather than in a multivitamin.

CONCLUSION

Consistency of donor responses may be insufficient for use in guiding donor eligibility. Referring donors to their pill bottles was unsuccessful in improving the high frequency of uncertain responses. Incorporating IS into donor eligibility determinations is a complex endeavor that will benefit from careful planning and from post-implementation monitoring.