Interdonation Interval Research Articles

Iron deficiency in blood donors: the REDS‐II Donor Iron Status Evaluation (RISE) study

Blood donors are at risk of iron deficiency. We evaluated the effects of blood donation intensity on iron and hemoglobin (Hb) in a prospective study. Four cohorts of frequent and first-time or reactivated (FT/RA) blood donors (no donation in 2 years), female and male, totaling 2425, were characterized and followed as they donated blood frequently. At enrollment and the final visit, ferritin, soluble transferrin receptor (sTfR), and Hb were determined. Models to predict iron deficiency and Hb deferral were developed. Iron depletion was defined at two levels: iron deficiency erythropoiesis (IDE) [log(sTfR/ferritin) ≥ 2.07] and absent iron stores (AIS; ferritin < 12 ng/mL). Among returning female FT and RA donors, 20 and 51% had AIS and IDE at their final visit, respectively; corresponding proportions for males were 8 and 20%. Among female frequent donors who returned, 27 and 62% had AIS and IDE, respectively, while corresponding proportions for males were 18 and 47%. Predictors of IDE and/or AIS included a higher frequency of blood donation in the past 2 years, a shorter interdonation interval, and being female and young; conversely, taking iron supplements reduced the risk of iron depletion. Predictors of Hb deferral included female sex, black race, and a shorter interdonation interval. There is a high prevalence of iron depletion in frequent blood donors. Increasing the interdonation interval would reduce the prevalence of iron depletion and Hb deferral. Alternatively, replacement with iron supplements may allow frequent donation without the adverse outcome of iron depletion.

Interdonation intervals and patterns of return among blood donors in Brazil

In Brazil, most donations come from repeat donors, but there are little data on return behavior of donors. Donors who made at least one whole blood donation in 2007 were followed for 2 years using a large multicenter research database. Donation frequency, interdonation intervals, and their association with donor demographics, status, and type of donation were examined among three large blood centers in Brazil, two in the southeast and one in the northeast. In 2007, of 306,770 allogeneic donations, 38.9% came from 95,127 first-time donors and 61.1% from 149,664 repeat donors. Through December 31, 2009, a total of 28.1% of first-time donors and 56.5% of repeat donors had donated again. Overall, the median interdonation interval was approximately 6 months. Among men it was 182 and 171 days for first-time and repeat donors, and among women, 212 and 200 days. Predictors of return behavior among first-time donors were male sex (odds ratio [OR], 1.17; 95% confidence interval [CI], 1.13-1.20), community donation (OR, 2.26; 95% CI, 2.20-2.33), and age 24 years or less (OR, 0.62-0.89 for donors ≥ 25 years). Among repeat donors predictors were male sex (OR, 1.35; 95% CI, 1.32-1.39), age 35 years or more (OR, 1.08-1.18 vs. ≤ 24 years), and community donation (OR, 2.39; 95% CI, 2.33-2.44). Differences in return by geographic region were evident with higher return rates in the northeast of Brazil. These data highlight the need to develop improved communication strategies for first-time and replacement donors to convert them into repeat community donors.

Donation return time at fixed and mobile donation sites

This study investigated the effect of blood donation environment, fixed or mobile with differing sponsor types, on donation return time. Data from 2006 through 2009 at six US blood centers participating in the Retrovirus Epidemiology Donor Study-II (REDS-II) were used for analysis. Descriptive statistics stratified by whole blood (WB), plateletpheresis (PP), and double red blood cell (R2) donations were obtained for fixed and mobile locations, including median number of donations and median interdonation interval. A survival analysis estimated median return time at fixed and mobile sites, while controlling for censored return times, demographics, blood center, and mandatory recovery times. Two-thirds (67.9%) of WB donations were made at mobile sites, 97.4% of PP donations were made at fixed sites, and R2 donations were equally distributed between fixed and mobile locations. For donations at fixed sites only or alternating between fixed and mobile sites, the highest median numbers of donations were nine and eight, respectively, and the shortest model-adjusted median return times (controlling for mandatory eligibility times of 56 and 112 days) were 36 and 30 days for WB and R2 donations, respectively. For PP donations, the shortest model-adjusted median return time was 23 days at a fixed location and the longest was 693 days at community locations. WB, PP, and R2 donors with the shortest time between donations were associated with fixed locations and those alternating between fixed and mobile locations, even after controlling for differing mandatory recovery times for the different blood donation procedures.

Progress in monitoring blood safety

Progress in monitoring blood safety

Frequent plateletpheresis does not clinically significantly decrease platelet counts in donors

In October 2005, the US Food and Drug Administration (FDA) issued draft guidance on collecting platelets (PLTs) by automated methods. The FDA proposed limiting collections to 24 components, rather than 24 procedures, annually with up to 3 components per procedure. The rationale was from literature suggesting frequent PLT collection resulted in significant declines in donor PLT counts. Additional requirements for minimal interdonation intervals were proposed. Plateletpheresis records at a regional blood center with predonation PLT counts were used to assess the impact of the restriction on PLT collections. They were reviewed to demonstrate the effects of collection frequency, number of products collected, and interdonation interval on donor PLT counts. Total protein and albumin levels were compared in a subset of 24-times-per-year PLT donors and control whole-blood donors. A limit of 24 components would require replacement of approximately 20 percent of the donor base to recover lost components. No clinically important decrease in PLT counts before donation was seen in donors donating multiple PLT components up to 24 times per year, regardless of interdonation interval. No frequent donor was deferred for a PLT count less than 150 x 10(9) per L. Short interdonation intervals were associated with statistically but not clinically important decreases in PLT counts. Protein levels were not distinguishable between PLT donors and controls. The proposed restrictions are not required to prevent thrombocytopenia in frequent PLT donors and would adversely impact the supply of apheresis PLTs. Protein levels are maintained in these high-frequency donors.

Selection of whole‐blood donors for hemoglobin testing by use of historical hemoglobin values

Usually, a predonation hemoglobin (Hb) measurement must precede blood donation. Hb values of a donor's previous donation might be used for selecting a subgroup in which predonation Hb measurements are unnecessary. Only donors with historical Hb values below 129 or 139 g per L for female and male donors, respectively, underwent venous Hb measurement before phlebotomy with an automated hematology analyzer. All other donor phlebotomies were collected without initial Hb testing. Hb values from diversion samples from 81,913 consecutive donors between May 2003 and November 2005 were subsequently analyzed as representing their present values. Donors were grouped according to interdonation intervals of less than 6, 6 to 11, 12 to 23, and 24 months or more. The arithmetic mean deviation between historical and present Hb values was between -0.3 and +1.8 g per L for each group (mean deviation, 5.2-6.7 g/L). Not testing selected donors spared 77.7 percent from a prephlebotomy Hb measurement and showed a specificity of 29 percent. Sensitivities for detection of donors below Hb limits (between 56% and 67% for the different subgroups) and donors with Hb values below 110 g per L (82%-88%) were at least comparable to capillary Hb screening. A total of 4.8 percent of donors were phlebotomized with values below 125 and 135 g per L, whereas only 0.016 percent of donors were bled despite Hb levels below 110 g per L. Selecting donors for a current Hb measurement based upon their last whole-blood predonation Hb value is a useful method, even after prolonged interdonation intervals.

The Residual Risk of Transfusion-Transmitted HIV Infection in a Public Brazilian Blood Center.

Estimating risks of transfusion-transmitted infections is essential for monitoring blood safety and for helping physicians and patients decide about the risks/benefits of an allogeneic transfusion. In 2000, the residual risk of HIV in our institution was estimated in 1/325,000 units transfused and the prevalence of HIV among all blood donors was 0.06%. The goal of this study was to calculate the current residual risk of transfusion-transmitted HIV infection in the Regional Blood Center of Ribeirão Preto, University of São Paulo, Brazil. We evaluated 292,587 repeated donations of a total of 403,568 donations between january/2002 and december/2005. During this period, we identified 43 seroconversions among the repeated donors. The serological tests performed were 2 different enzyme immunoassays (EIA): HIV 1/2 and a conjugated p24 antigen/antibody as screening tests and Western Blot as a confirmatory test for all positive samples. In order to calculate the residual risk, we used the incidence rate/window period (IR/WP) model, developed in parallel by investigators from the National Heart, Lung and Blood Institute-sponsored Retrovirus Epidemiology Donor Study (REDS), the CDC and the American Red Cross. The IR takes into account the number of incident cases (numerator), the total number of repeated donations and the mean interdonation interval length (multiplication of the last two entities provides the number of person-years at risk or denominator). The mean interdonation interval length can be substituted for the mean seroconversion interval length for all incident cases if the first one can not be accurately measured, so we used this alternative. Once the IR is known, we calculated the residual risk dividing the IR by 365.25 days and then multiplying by the WP of the test used (p24=15 days). Our results are: IR= 43 cases/292,587 repeated donations × 3.2 years = 4.59×10−5. The current residual risk is (IR/365.25 days) × 15 days= 1.5/million units transfused or 1/667,000 units. The prevalence of HIV among all blood donors in 2005 was 0.035%. Although we know that the correlation between prevalence and residual risk is not straightforward, they have a certain degree of correlation and they both have declined since 2000. During these last 5 years, we have made some modifications in our donor selection towards a more rigorous donor screening and since january/2002 we have introduced the p24 antigen/antibody EIA as part of the screening serological tests. We concluded that the more stringent donor risk factor screening and the introduction of the p24 antigen test have substantially reduced the residual risk of transfusion-transmitted HIV infection in our institution.

Infektionsepidemiologische Daten von Blutspendern 2003–2004

The Robert Koch Institute collects and evaluates data on the prevalence and incidence of HIV, hepatitis C (HCV), hepatitis B (HBV) and syphilis infections among blood and plasma donors in Germany in accordance with Article 22 of the Transfusion Act. This surveillance permits an assessment of the occurrence of infections in the blood donor population and consequently the safety of the collected donations. This report includes data from all blood donation services in Germany for 2003 and 2004. Altogether 7.09 million and 6.37 million donations or blood samples from prospective donors were screened in 2003 and 2004, respectively. In 2003 the prevalence rates of the relevant infections (per 100,000 donations) were 8.2 for HIV, 99.3 for HCV, 158.9 for HBV and 34.4 for syphilis. In 2003 the rates of seroconversion (per 100,000 donations) were 0.8 for HIV, 1.2 for HCV, 1.0 for HBV and 1.5 for syphilis in 2003. In 2004 the prevalence rates (per 100,000 donations) were 4.8 for HIV, 85.3 for HCV, 156.3 for HBV and 36.8 for syphilis. In 2004 the rates of seroconversion (per 100,000 donations) were 0.9 for HIV, 1.3 for HCV, 0.6 for HBV and 2.0 for syphilis. The analysis showed a very low incidence of infections with a decreasing trend for HCV infections and an increase in HIV and syphilis infections. The latter needs to be monitored carefully and possible causes evaluated. The quality of the reported data has improved compared to previous years. Still, some problems remain with the differentiation of the data according to sex, age and interdonation interval as well as reporting by individual blood donation centres as required by the Transfusion Act.

Estimates of the frequency of HBV, HCV, and HIV infectious donations entering the blood supply in the United Kingdom, 1996 to 2003.

Several new tests have been recently introduced by the United Kingdom Blood Services to improve safety. The frequency (or risk) of hepatitis B virus (HBV), hepatitis C virus (HCV) and HIV infectious donations entering the UK blood supply during 1996-2003 has been estimated. These years span the introduction of nucleic acid testing (NAT) for HCV, HIV combination antigen and antibody test and NAT for HIV. The frequency of an infectious donation entering the blood supply due to i) the window period, ii) assay failures and iii) human and technical errors in testing and processing, was estimated. The window period risk was estimated using the incidence of infection in donors and the length of the window period for tests in use, with an adjustment for atypical inter-donation intervals in seroconverting donors. The estimated frequency of infectious donations entering the blood supply during 1996-2003 was 1.66, 0.80 and 0.14 per million for HBV, HCV and HIV respectively. HCV NAT resulted in an over 95% fall in the risk of HCV. Current usage of HIV combined antibody-antigen tests and of HIV NAT reduced the estimated risk of HIV by 10%. Since 1996, the risk of transfusion-transmitted HBV, HCV and HIV infection in the UK has been lowered by several improvements to donation testing, although the absolute reduction in risk has been small. Vigilance for errors and the affects of donor selection may be as or more important than further reductions to window periods of tests for improving blood safety with respect to HBV, HCV and HIV.

Analysis of donor return behavior. Retrovirus Epidemiology Donor Study.

Efforts to provide a safe, adequate blood supply have been inhibited by persistent shortages attributed to a lack of motivation on the part of the general public and inefficiency in recruiting processes. This study examined whether frequency of donations and/or timing of subsequent donations by first-time donors related to donor demographics. Characteristics of 879,816 first-time donors making at least one whole-blood donation were analyzed. Cox proportional-hazards regression models evaluated the first 10 return times separately, and a recurrent-event Cox model was applied to simultaneously evaluate the first five returns. The shorter the donation interval between the first two donations, the more likely the donor was to make subsequent donations. The proportion of repeat donors increased with education level. Rate of donation increased with age and education. The recurrent-event Cox regression model showed that Rh-negative donors, older donors, and donors who had completed college had higher donation return rates. Time to return for second donation was associated with total number of donations made and with return rate for subsequent returns. Age was the strongest predictor of high donation frequency and early-return rate. Relationships between interdonation interval and the number of future donations may prove useful in understanding return behavior and developing donor recruitment and retention strategies.

A method for estimating hepatitis B virus incidence rates in volunteer blood donors. National Heart, Lung, and Blood Institute Retrovirus Epidemiology Donor Study.

Calculations of the incidence of hepatitis B virus (HBV) infections in the blood donor setting that are based solely on data for seroconversion to hepatitis B surface antigen (HBsAg) will underestimate the incidence due to the transient nature of antigenemia. Estimates based on antibody to hepatitis B core antigen will overestimate the incidence due to false-positive results caused by the nonspecificity of the test. Serologic test results were obtained from multiple-time volunteer donors at five United States blood centers from January 1991 through December 1993. The observed HBsAg seroconversion rate was multiplied by an adjustment factor, derived from the weighted average probability of a positive HBsAg test for HBV-infected donors who become chronic carriers, for donors with a primary antibody response without detectable antigenemia, and for donors who develop transient antigenemia. Among 586,507 multiple-time donors giving 2,318,356 donations and observed for 822,426 person-years, the HBsAg incidence rate was 4.01 per 100,000 person-years. On the basis of prior reports of the duration of HBsAg positivity and the observed distribution of interdonation intervals among the study group, there was an estimated 53-percent chance that an HBV-infected donor with transient antigenemia would have a positive HBsAg test result. If 70 percent of newly HBV-infected adults have transient antigenemia, 25 percent have a primary antibody response without primary antigenemia, and 5 percent become chronic carriers, the overall chance of being detected by the HBsAg test was 42 percent, for an adjustment factor of 2.38. The total HBV incidence rate, therefore, was estimated to be 9.54 per 100,000 person-years. The crude HBV incidence rate observed from HBsAg test results will underestimate the true rate. The adjusted HBV incidence rate should be used in applications such as estimations of residual HBV risk to the blood supply and projections of the benefits of screening for HBV DNA.