Zinc protoporphyrin levels have added value in the prediction of low hemoglobin deferral in whole blood donors

Decision curve analysis confirms higher clinical utility of multi-domain versus single-domain prediction models in patients with open abdomen treatment for peritonitis

BACKGROUND

Prediction modelling increasingly becomes an important risk assessment tool in perioperative systems approaches, e.g. in complex patients with open abdomen treatment for peritonitis. In this population, combining predictors from multiple medical domains (i.e. demographical, physiological and surgical variables) outperforms the prediction capabilities of single-domain prediction models. However, the benefit of these prediction models for clinical decision-making remains to be investigated. We therefore examined the clinical utility of mortality prediction models in patients suffering from peritonitis with a decision curve analysis.

METHODS

In this secondary analysis of a large dataset, a traditional logistic regression approach, three machine learning methods and a stacked ensemble were employed to examine the predictive capability of demographic, physiological and surgical variables in predicting mortality under open abdomen treatment for peritonitis. Calibration was examined with calibration belts and predictive performance was assessed with the area both under the receiver operating characteristic curve (AUROC) and under the precision recall curve (AUPRC) and with the Brier Score. Clinical utility of the prediction models was examined by means of a decision curve analysis (DCA) within a treatment threshold range of interest of 0-30%, where threshold probabilities are traditionally defined as the minimum probability of disease at which further intervention would be warranted.

RESULTS

Machine learning methods supported available evidence of a higher prediction performance of a multi- versus single-domain prediction models. Interestingly, their prediction performance was similar to a logistic regression model. The DCA demonstrated that the overall net benefit is largest for a multi-domain prediction model and that this benefit is larger compared to the default "treat all" strategy only for treatment threshold probabilities above about 10%. Importantly, the net benefit for low threshold probabilities is dominated by physiological predictors: surgical and demographics predictors provide only secondary decision-analytic benefit.

CONCLUSIONS

DCA provides a valuable tool to compare single-domain and multi-domain prediction models and demonstrates overall higher decision-analytic value of the latter. Importantly, DCA provides a means to clinically differentiate the risks associated with each of these domains in more depth than with traditional performance metrics and highlighted the importance of physiological predictors for conservative intervention strategies for low treatment thresholds. Further, machine learning methods did not add significant benefit either in prediction performance or decision-analytic utility compared to logistic regression in these data.

Iron Deficiency and Blood Donation: Links, Risks and Management

The purpose of this review is to raise awareness about the frequently underappreciated association of blood donation with iron deficiency, and to describe methods for its prevention and management. Blood donors cannot expect any health benefits from the donation but have justified expectations of no harm. Iron deficiency without anemia (IDWA) and iron deficiency anemia (IDA) are common consequences of regular blood donation, and this activity is the most important factor affecting iron status in regular blood donors. Awareness of blood donation as a primary cause of sideropenia is surprisingly low among physicians. Blood donation screening identifies potential donors with IDA but is frequently inadequate to detect IDWA. For the assessment of body iron stores, plasma or serum ferritin, transferrin saturation (TSAT) and soluble transferrin receptors (sTfR) concentrations are the most widely used biochemical markers, although the percentage of hypochromic mature erythrocytes and the hemoglobin content of reticulocytes are also useful. IDWA can be prevented by limiting the total volume of blood collected, by iron deficiency screening and deferral of sideropenic donors, by prolonging the interdonation intervals, and by iron supplementation between donations. IDWA tends to be more prevalent in younger people, females, and high-intensity donors. A potentially effective strategy to address sideropenia in blood donors is serum ferritin testing, but this may lead to a higher rate of deferral. Most regular blood donors cannot replenish their iron deficit by an iron-rich diet alone and will benefit from low-dose oral iron administration with various commercially available products post-donation, a well-tolerated strategy. However, valid concerns exist regarding the possibility of worsening the iron overload in donors with undiagnosed hemochromatosis or masking the symptoms of a clinically important gastrointestinal hemorrhage or other underlying medical condition. Finally, educational efforts should be intensified to improve the awareness of blood donation as a primary cause of iron deficiency among physicians of all specialties.

Anti-aging properties of Dendrobium nobile Lindl.: From molecular mechanisms to potential treatments

ETHNOPHARMACOLOGICAL RELEVANCE

Dendrobium Nobile Lindl. (DNL) is one of the central herbs in traditional Chinese medicine which mainly distributes in Guizhou, Yunnan, Guangxi and other sub-tropical areas south of the Yangtze River. In the past decades, it has been used to treat tumors, hyperglycemia, hyperlipidemia, and diseases of the nervous system that may be caused by aging.

AIM OF THE REVIEW

The purpose of this review is to summarize the anti-aging information of DNL from the molecular mechanism level, including classic theories related to aging, main chemical components, pharmacological research and anti-aging theory based on traditional Chinese medicine theory, for exploring the future development and clinical treatment.

MATERIALS AND METHODS

The information in this paper has been collected from the scientific literature databases including PubMed, Google Scholar, Web of Science, Science Direct, Springer, China National Knowledge Infrastructure, published books, Ph.D. and M.S. dissertations systematically.

RESULTS

In this paper, we have reviewed the several mechanisms underlying the potential effects of DNL on the prevention of aging, including the scavenging of free radicals for oxidation, delaying of DNA impairment, inhibition of apoptosis, and alteration of DNA methylation. Together with the theory of telomeres, this review also has summarized recent research progress in the use of DNL and its traditional efficacy.

CONCLUSIONS

We conclude that "strengthening Yin and benefiting the spirit", "thickening the intestine and stomach", "lightning the body and prolonging the life-span", and delaying aging, are key effects of DNL that can be used to combat age-related diseases (ARDs) such as Alzheimer's disease, hyperlipidemia, and diabetes. This review provides a reference for future study of ARDs and the clinical application of DNL.

Impact of risk-dependent interventions on low haemoglobin deferral rates in whole blood donors

BACKGROUND

Blood donors with a relatively low haemoglobin (Hb) level at their previous donation attempt have an increased risk of Hb deferral at the subsequent donation attempt. The aim of this study was to investigate whether the interventions prolongation of donation interval and/or a dietary advice decrease the Hb deferral rate.

METHODS

11 897 whole blood donors with Hb levels from below to 0·2 mmol/l above the cut-off level for donation received either no intervention, a prolongation of the donation interval to six or twelve months, a dietary advice, or both. Deferral rates for low Hb levels at the subsequent donation attempt were compared in the different intervention groups. Additionally, the effects of the interventions on Hb deferral risk and donor return for a subsequent donation attempt were analysed using generalized estimating equations.

RESULTS

The Hb deferral rate was substantially lower in the group that received a prolongation of the donation interval to six months than in the Control Group (12·9% vs. 6·3% in men and 20·4% vs. 13·4% in women). However, the additional benefit of twelve over 6-month interval prolongation was small, and no benefit of a dietary advice showed up. On the other hand, receiving a dietary advice increased the likelihood of donor return for a subsequent donation attempt.

CONCLUSION

Implementation of a protocol for the prolongation of donation intervals to six months for donors with Hb levels from below to slightly above the cut-off level for donation may reduce the deferral rate for low Hb levels while keeping donor lapse at a minimum.

Lifestyle behaviours, ethnicity and menstruation have little added value in prediction models for low haemoglobin deferral in whole blood donors

OBJECTIVE

To investigate the added value of questionnaire-based predictors to existing prediction models for low haemoglobin (Hb) deferral in whole blood donors.

BACKGROUND

Prediction models for Hb deferral risk can be applied in the invitation process of donors for a blood donation. Existing prediction models are based on routinely collected data. The model performance might be improved by the addition of predictive factors.

METHODS

The added value of food consumption, smoking, physical activity, ethnicity and menstruation in the prediction of Hb deferral was assessed by comparing the existing models with extended models using the following measures: model X² , concordance (c)-statistic and net reclassification improvement (NRI).

RESULTS

Addition of one candidate predictor to the models did not substantially improve the model performance. Addition of multiple new candidate predictors significantly increased the model X² (from 137 to 159 for men, and from 157 to 199 for women) and resulted in a non-significant increase of the c-statistic (from 0.85 to 0.87 for men, and from 0.78 to 0.81 for women). The NRI for men was 11.4% and for women 1.5% after addition of multiple predictors.

CONCLUSION

Addition of lifestyle behaviours, ethnicity or menstruation to prediction models for low Hb deferral in whole blood donors improved the model performance, but not substantially. For easy use in practice, we do not recommend addition of the investigated predictors to the prediction models.

Utility of zinc protoporphyrin in management of whole blood donors

BACKGROUND

Deferral for low hemoglobin (Hb) increases the likelihood that donors do not return for future donations. Zinc protoporphyrin (ZPP) has been described as a sensitive marker of iron-deficient erythropoiesis, before Hb decreases. It is a relatively cheap, rapid, and easy-to-perform measurement in a drop of whole blood. To assess the utility of ZPP measurement in donor management we examined whether ZPP and Hb levels among first-time donors differ from repeat donors. We further explored whether ZPP increases over subsequent donations at a donor population level and whether increasing ZPP levels coincide with decreasing Hb levels and donor deferral.

STUDY DESIGN AND METHODS

We included first-time (n = 4983) and repeat (n = 3533) whole blood donors from the ZPP and Iron in the Netherlands Cohort (ZINC) study. ZPP and Hb were measured at each subsequent donation during a 4-year period after inclusion in the study.

RESULTS

Median ZPP levels were higher in repeat than in first-time donors. In first-time donors, especially women, ZPP levels were increased with a corresponding decline in Hb levels over subsequent donations. ZPP levels were increased among first-time donors deferred for low Hb.

CONCLUSION

Our results suggest that adding ZPP to Hb measurements in the daily blood collection setting, especially for first-time donors and first-time female donors may add to the identification of a donor subpopulation with low functional iron stores.

Genetic factors associated with iron storage in Australian blood donors

BACKGROUND

Blood donors are at risk of developing iron deficiency and/or iron deficiency anaemia. This may affect their health and affect their eligibility to give subsequent donations. Investigating genetic factors that may predispose donors to high or low iron stores is of interest; this may assist with providing optimal management strategies for maintaining donor health. This study aimed to investigate whether the presence of selected single nucleotide polymorphisms (SNPs) affecting parameters of iron status were associated with ferritin levels in Australian donors.

MATERIALS AND METHODS

Samples (n=800) were collected from non-first-time blood donors in Queensland. Plasma ferritin levels were quantified and the genotypes for ten SNPs, identified by a review of relevant literature, were determined for each sample. Associations between SNPs and ferritin levels were investigated.

RESULTS

Three SNPs were associated with ferritin levels. In male donors, high ferritin levels were associated with the variant allele (G) of the SNP rs3923809 in the BTBD9 gene. An association with ferritin levels was also identified with the SNP rs235756 in the BMP2 gene in males. The SNP rs4820268 in the TMPRSS6 gene was associated with ferritin levels in females, with donors with the AG genotype being three times more likely to have low ferritin levels.

DISCUSSION

Variants in the genes TMPRSS, BTBD9 and BMP2 were associated with ferritin levels in Australian blood donors. These findings provide support that genetic testing may be useful for the generation of predictive algorithms that may allow for management strategies to be tailor-made for individual donors.

Assessing the Clinical Impact of Risk Prediction Models With Decision Curves: Guidance for Correct Interpretation and Appropriate Use

The decision curve is a graphical summary recently proposed for assessing the potential clinical impact of risk prediction biomarkers or risk models for recommending treatment or intervention. It was applied recently in an article in Journal of Clinical Oncology to measure the impact of using a genomic risk model for deciding on adjuvant radiation therapy for prostate cancer treated with radical prostatectomy. We illustrate the use of decision curves for evaluating clinical- and biomarker-based models for predicting a man's risk of prostate cancer, which could be used to guide the decision to biopsy. Decision curves are grounded in a decision-theoretical framework that accounts for both the benefits of intervention and the costs of intervention to a patient who cannot benefit. Decision curves are thus an improvement over purely mathematical measures of performance such as the area under the receiver operating characteristic curve. However, there are challenges in using and interpreting decision curves appropriately. We caution that decision curves cannot be used to identify the optimal risk threshold for recommending intervention. We discuss the use of decision curves for miscalibrated risk models. Finally, we emphasize that a decision curve shows the performance of a risk model in a population in which every patient has the same expected benefit and cost of intervention. If every patient has a personal benefit and cost, then the curves are not useful. If subpopulations have different benefits and costs, subpopulation-specific decision curves should be used. As a companion to this article, we released an R software package called DecisionCurve for making decision curves and related graphics.

Laboratory and genetic assessment of iron deficiency in blood donors

More than 9 million individuals donate blood annually in the United States. Between 200 and 250 mg of iron is removed with each whole blood donation, reflecting losses from the hemoglobin in red blood cells. Replenishment of iron stores takes many months, leading to a high rate of iron depletion. In an effort to better identify and prevent iron deficiency, blood collection centers are now considering various strategies to manage donor iron loss. This article highlights laboratory and genetic tests to assess the iron status of blood donors and their applicability as screening tests for blood donation.

Low hemoglobin deferral in blood donors

Low hemoglobin deferral occurs in about 10% of attempted whole blood donations and commonly is a consequence of iron deficiency anemia. Pre-menopausal women often have iron deficiency anemia caused by menstruation and pregnancy and have low hemoglobin deferral on their first donation attempt. Frequent donors also develop iron deficiency and iron deficiency anemia because blood donation removes a large amount of iron from the donor and the 56-day minimum inter-donation interval for donors in the United States is not sufficient for recovery of hemoglobin and iron stores. Other causes for low hemoglobin deferral range from a medically insignificant deferral of a woman with hemoglobin between 12.0 and 12.4 g/dL, which is within the normal reference range but below the 12.5 g/dL needed to donate blood, to anemia caused by an unrecognized malignancy in a "healthy" individual attempting to donate blood. The diverse causes of anemia in blood donors make it difficult to provide accurate information to donors about the cause of their low hemoglobin deferral and complicate implementation of programs to prevent them by blood collecting agencies. This article reviews how hemoglobin is measured and the demographics and causes of low hemoglobin deferral in blood donors. It provides recommendations for how blood collection agencies can provide donors with accurate information about the cause of their deferral and discusses programs that can be implemented to decrease these deferrals in regular donors.