Blood donors attending a donation session may be deferred from donating blood due to a failure to meet low hemoglobin (Hb) thresholds. This costs the blood donor service and donors valuable time and resources. In addition, donors who are deferred may have more symptoms, and as a direct and/or indirect effect of their experience, return rates of donors deferred for low Hb are reduced, even in repeat donors. It is therefore vital that low Hb deferral (LHD) is minimized. The aim of this updated systematic review is to expand the evidence base for factors which affect a donor's risk of deferral due to low Hb. Studies were identified by searching MEDLINE, Embase, The Cochrane Library, and the WHO International Clinical Trials Registry to March 2019. Demographic data, donor history, hematological/biological factors, and the primary outcome of deferral due to low Hb were extracted. Our primary outcome was deferral due to low Hb. Analyses were descriptive and quantitative; pooled odds ratios (ORs) and 95% confidence intervals (CIs) were obtained by meta-analysis using random-effects models. A total of 116 studies met the inclusion criteria. Meta-analysis showed a significantly greater risk of LHD in females compared with males in studies applying universal Hb thresholds for males and females (OR 14.62 95% CI 12.43-17.19) and in those which used sex-specific thresholds (OR 5.73, 95% CI 4.36-7.53). Higher rates of LHD were also associated with increasing age in men, low body weight, shorter interdonation interval, donors of Hispanic or African descent, higher ambient temperature, donors with low ferritin levels, and donation in a fixed donor center. There was conflicting evidence on the effect of new and repeat donor status, and blood group. This work has strengthened the evidence of the previous review in identifying factors that should be considered in studies of donor deferral and highlighting areas in need of further study, including ABO and Rh blood groups, previous platelet donation, diet, smoking, time of day, and genetic data. These factors may lead to individually tailored donation criteria for safe and efficient donation in the future.

由于未能达到低血红蛋白 (Hb) 阈值，参加献血会议的献血者可能会被推迟献血。这会耗费献血者服务和献血者宝贵的时间和资源。此外，被推迟的捐献者可能有更多的症状，并且作为他们经验的直接和/或间接影响，因低 Hb 而推迟的捐献者的返回率会降低，即使是重复捐献者也是如此。因此，将低 Hb 延迟 (LHD) 降至最低至关重要。本次更新的系统评价的目的是扩大影响捐献者因低 Hb 而推迟献血风险的因素的证据基础。通过搜索 MEDLINE、Embase、The Cochrane确定研究图书馆和 WHO 国际临床试验登记处截至 2019 年 3 月。提取了人口统计数据、供体历史、血液学/生物学因素以及因低 Hb 而推迟的主要结果。我们的主要结果是由于低 Hb 而推迟。分析是描述性和定量的；使用随机效应模型通过荟萃分析获得合并比值比 (OR) 和 95% 置信区间 (CI)。共有 116 项研究符合纳入标准。Meta 分析显示，在对男性和女性应用通用 Hb 阈值（OR 14.62 95% CI 12.43-17.19）和使用性别特异性阈值（OR 5.73, 95%）的研究中，女性患 LHD 的风险显着高于男性CI 4.36-7.53）。较高的 LHD 发生率也与男性年龄增长、低体重、较短的捐献间隔时间有关，西班牙裔或非洲裔捐献者、环境温度较高、铁蛋白水平低的捐献者、固定捐献中心捐献者。关于新的和重复的捐献者身份以及血型的影响存在相互矛盾的证据。这项工作加强了先前审查的证据，以确定捐助者延迟研究中应考虑的因素，并强调需要进一步研究的领域，包括 ABO 和 Rh 血型、先前的血小板捐献、饮食、吸烟、一天中的时间、和基因数据。这些因素可能会导致将来为安全有效的捐赠制定个性化的捐赠标准。和血型。这项工作加强了先前审查的证据，以确定捐助者延迟研究中应考虑的因素，并强调需要进一步研究的领域，包括 ABO 和 Rh 血型、先前的血小板捐献、饮食、吸烟、一天中的时间、和基因数据。这些因素可能会导致将来为安全有效的捐赠制定个性化的捐赠标准。和血型。这项工作加强了先前审查的证据，以确定捐助者延迟研究中应考虑的因素，并强调需要进一步研究的领域，包括 ABO 和 Rh 血型、先前的血小板捐献、饮食、吸烟、一天中的时间、和基因数据。这些因素可能会导致将来为安全有效的捐赠制定个性化的捐赠标准。