Estimating the serological underrecognition of patients with weak or partial RHD variants

BACKGROUND

For patients with weak or discrepant RhD RBC phenotypes, RHD genotyping is employed to determine need for RhD-negative management. However, many RHD variants are type D-negative or D-positive. Serological recognition rates (RRs) of weak and partial RHD variants are poorly characterized.

STUDY DESIGN AND METHODS

Four US studies employing RHD genotyping for weak or discrepant RhD phenotypes provided data for race/ethnicity-specific serological recognition. Three studies used microplate, and 1 used gel and tube; 2 had anti-D data. We obtained White and Hispanic/Latino allele frequencies (AFs) of weak D types 1, 2, and 3 single-nucleotide variants (SNVs) from the Genome Aggregation Database (gnomAD, v4.0.0) and devised Hardy-Weinberg-based formulas to correct for gnomAD's overcount of hemizygous RHD SNVs as homozygous. We compiled common partial RHD AF from genotyped cohorts of US Black or sickle cell disease subjects. From variant AF, we calculated hemizygous-plus-homozygous genetic prevalences. Serological prevalence: genetic prevalence ratios yielded serological RRs.

RESULTS

Overall RRs of weak D types 1-3 were 17% (95% confidence interval 12%-24%) in Whites and 12% (5%-27%) in Hispanics/Latinos. For eight partial RHD variants in Blacks, overall RR was 11% (8%-14%). However, DAR RR was 80% (38%-156%). Compared to microplate, gel-tube recognition was higher for type 2 and DAU5 and lower for type 4.0. Anti-D was present in 6% of recognized partial RHD cases, but only in 0.7% of estimated total genetic cases.

DISCUSSION

Based on AF, >80% of patients with weak or partial RHD variants were unrecognized serologically. Although overall anti-D rates were low, better detection of partial RHD variants is desirable.

Antibody Titers in Transfusion Medicine: A Critical Reevaluation of Testing Accuracy, Reliability, and Clinical Use

CONTEXT.—

Substantial variability between different antibody titration methods has been identified since the development and introduction of the uniform procedure in 2008.

OBJECTIVE.—

To determine whether more recent methods or techniques decrease interlaboratory and intralaboratory variation measured using proficiency testing.

DESIGN.—

Proficiency test data for antibody titration between 2014 and 2018 were obtained from the College of American Pathologists. Interlaboratory and intralaboratory variations were compared by analyzing the distribution of titer results by method and phase, comparing the results against the supplier's quality control titer, and by evaluating the distribution of paired titer results when each laboratory received a sample with the same titer twice.

RESULTS.—

A total of 1337 laboratories participated in the antibody titer proficiency test during the study period. Only 54.1% (5874 of 10 852) of anti-D and 63.4% (3603 of 5680) of anti-A reported responses were within 1 titer of the supplier's intended result. Review of the agreement between laboratories of the same methodology found that 78.4% (3139 of 4004) for anti-A and 89.0% (9655 of 10 852) of laboratory responses for anti-D fell within 1 titer of the mode response. When provided with 2 consecutive samples of the same titer (anti-D titer: 16), 85% (367 of 434) of laboratories using the uniform procedure and 80% (458 of 576) using the other method reported a titer difference of 1 or less.

CONCLUSIONS.—

Despite advances, interlaboratory and intralaboratory variance for this assay remains high in comparison with the strong reliance on titer results in clinical practice. There needs to be a reevaluation of the role of this test in clinical decision-making.

Transfusion-Transmitted Cache Valley Virus Infection in a Kidney Transplant Recipient With Meningoencephalitis

BACKGROUND

Cache Valley virus (CVV) is a mosquito-borne virus that is a rare cause of disease in humans. In the fall of 2020, a patient developed encephalitis 6 weeks following kidney transplantation and receipt of multiple blood transfusions.

METHODS

After ruling out more common etiologies, metagenomic next-generation sequencing (mNGS) of cerebrospinal fluid (CSF) was performed. We reviewed the medical histories of the index kidney recipient, organ donor, and recipients of other organs from the same donor and conducted a blood traceback investigation to evaluate blood transfusion as a possible source of infection in the kidney recipient. We tested patient specimens using reverse-transcription polymerase chain reaction (RT-PCR), the plaque reduction neutralization test, cell culture, and whole-genome sequencing.

RESULTS

CVV was detected in CSF from the index patient by mNGS, and this result was confirmed by RT-PCR, viral culture, and additional whole-genome sequencing. The organ donor and other organ recipients had no evidence of infection with CVV by molecular or serologic testing. Neutralizing antibodies against CVV were detected in serum from a donor of red blood cells received by the index patient immediately prior to transplant. CVV neutralizing antibodies were also detected in serum from a patient who received the co-component plasma from the same blood donation.

CONCLUSIONS

Our investigation demonstrates probable CVV transmission through blood transfusion. Clinicians should consider arboviral infections in unexplained meningoencephalitis after blood transfusion or organ transplantation. The use of mNGS might facilitate detection of rare, unexpected infections, particularly in immunocompromised patients.

Obstetric and Newborn Weak D-Phenotype RBC Testing and Rh Immune Globulin Management Recommendations: Lessons From a Blinded Specimen-Testing Survey of 81 Transfusion Services

CONTEXT.—

Modern RHD genotyping can be used to determine when patients with serologic weak D phenotypes have RHD gene variants at risk for anti-D alloimmunization. However, serologic testing, RhD interpretations, and laboratory management of these patients are quite variable.

OBJECTIVE.—

To obtain interlaboratory comparisons of serologic testing, RhD interpretations, Rh immune globulin (RhIG) management, fetomaternal hemorrhage testing, and RHD genotyping for weak D-reactive specimens.

DESIGN.—

We devised an educational exercise in which 81 transfusion services supporting obstetrics performed tube-method RhD typing on 2 unknown red blood cell challenge specimens identified as (1) maternal and (2) newborn. Both specimens were from the same weak D-reactive donor. The exercise revealed how participants responded to these different clinical situations.

RESULTS.—

Of reporting laboratories, 14% (11 of 80) obtained discrepant immediate-spin reactions on the 2 specimens. Nine different reporting terms were used to interpret weak D-reactive maternal RhD types to obstetricians. In laboratories obtaining negative maternal immediate-spin reactions, 28% (16 of 57) performed unwarranted antiglobulin testing, sometimes leading to recommendations against giving RhIG. To screen for excess fetomaternal hemorrhage after a weak D-reactive newborn, 47% (34 of 73) of reporting laboratories would have employed a contraindicated fetal rosette test, risking false-negative results and inadequate RhIG coverage. Sixty percent (44 of 73) of laboratories would obtain RHD genotyping in some or all cases.

CONCLUSIONS.—

For obstetric and neonatal patients with serologic weak D phenotypes, we found several critical problems in transfusion service laboratory practices. We provide recommendations for appropriate testing, consistent immunohematologic terminology, and RHD genotype-guided management of Rh immune globulin therapy and RBC transfusions.

RHD genotyping to resolve weak and discrepant RhD patient phenotypes

BACKGROUND

We instituted RHD genotyping in our transfusion service for obstetrical patients and transfusion candidates. We sought to examine how RHD genotyping resolved weak or discrepant automated microplate direct agglutination (MDA) RhD phenotypings and impacted needs for Rh Immune Globulin (RhIG) and D-negative RBCs.

STUDY DESIGN AND METHODS

We investigated RhD phenotypes with equivocal or reagent-discrepant automated MDA (Immucor, Norcross, GA), weak-2+ immediate-spin tube typings, historically discrepant RhD typings, or D+ typings with anti-D. We performed microarray RHD genotyping (RHD BeadChip, Immucor BioArray Solutions, Warren, NJ). Patients were managed as D+ with weak-D types 1, 2, and 3, and as D-negative with all other results.

RESULTS

Our weak-D prevalence was 0.14%. Among 138 patients (73 obstetrics, 65 transfusion candidates), 38% had weak-D types 1, 2 or 3, 25% weak partial type 4.0, 21% other partial-D variant alleles, and 15% no variant detected. One novel allele with weak partial type 4.0 variants plus c.150T>C (Val50Val) was discovered. Weak D types 1, 2 or 3 were identified in 66% (48/73) of Whites versus 3% (2/62) of diverse ethnic patients (p < .0001). RHD genotyping changed RhD management in 60 patients (43%) (49 to D+, 11 to D-negative), resulting in net conservation of D-negative RBCs (98 avoided, 14 given) and RhIG (8 avoided, 3 given).

CONCLUSION

In our patient population, equivocal or reagent-discrepant MDA RhD phenotypes were highly specific for weak-D or partial-D RHD genotypes. Resolution of RHD genotype status reduced our use of D-negative RBCs and RhIG.

International guidelines regarding the role of IVIG in the management of Rh- and ABO-mediated haemolytic disease of the newborn

Haemolytic disease of the newborn (HDN) can be associated with significant morbidity. Prompt treatment with intensive phototherapy (PT) and exchange transfusions (ETs) can dramatically improve outcomes. ET is invasive and associated with risks. Intravenous immunoglobulin (IVIG) may be an alternative therapy to prevent use of ET. An international panel of experts was convened to develop evidence-based recommendations regarding the effectiveness and safety of IVIG to reduce the need for ETs, improve neurocognitive outcomes, reduce bilirubin level, reduce the frequency of red blood cell (RBC) transfusions and severity of anaemia, and/or reduce duration of hospitalization for neonates with Rh or ABO-mediated HDN. We used a systematic approach to search and review the literature and then develop recommendations from published data. These recommendations conclude that IVIG should not be routinely used to treat Rh or ABO antibody-mediated HDN. In situations where hyperbilirubinaemia is severe (and ET is imminent), or when ET is not readily available, the role of IVIG is unclear. High-quality studies are urgently needed to assess the optimal use of IVIG in patients with HDN.

Two Individuals with Rare Blocked Antigen Phenomenon and Coinciding Warm Autoantibody Mimicking Alloanti-Jk3 Resolved with JK Analysis

Introduction/Objective

Kidd antigens can bind complement (C3) as well as Kidd specific warm autoantibodies (WAAb). An 838G&gt;A single nucleotide variant (SNV) defines JK*01 and JK*02 which codes the antithetical Jka and Jk b, respectively. Both alleles translate the high prevalence (&gt;99%) Jk3 (JK3). The 130G&gt;A is associated with weak Jka and weak Jkb expression. In vivo binding of non-agglutinating globulins can cause false-negative phenotypes by means of the blocked antigen phenomenon (BAP).

Methods/Case Report

Transfusions were requested for a 74-year-old Caucasian (CA) female with Evan’s Syndrome, and an 85-year-old African American (AA) female with metastatic uterine cancer. Both had a history of nonspecific WAAb. Direct antiglobulin testing (DAT) detected moderate in vivo sensitization of IgG and C3. They phenotyped Jk(a- b-) with untreated and EDTA glycine-acid (EGA) treated IgG DAT-negative cells. Their serum contained anti-Jk3 reactivity, while a panreactive WAAb in the eluate reacted with Jk3- donor and EGA treated DAT-negative autologous cells. Weak anti-Jka and anti-Jkb reactivity remained in the alloadsorbed serum of the antithetical adsorbing cells.

Genetic testing of the CA revealed JK*01W.01(130A)/02 alleles, while cDNA confirmed the alleles would be transcribed into mRNA. Sequencing of the AA detected 130G/A, and 838G/A as well as other silent mutations predicting either a Jk(a+wb+) or Jk(a+b+w) phenotype. The CA received one compatible JK:-3 transfusion, and both individuals benefited from multiple least incompatible transfusions of Jk a+ and/or Jk b+ donors with expected hemoglobin increases (1 g/dL per transfusion). The CA serologically phenotyped Jk(a-b+) 132 days later following prolonged immunosuppressive therapy while a normocytic normochromic anemia and the WAAb persisted. No follow up evaluations of the AA are available.

Results (if a Case Study enter NA)

NA

Conclusion

Unexpected BAP can confound immunohematology testing and lead WAAbs mimicking alloanti-Jk3 to be mischaracterized as allogeneic. By predicting phenotypes, genetic analysis can aid serological techniques in antibody characterization and help circumvent complications searching for rare JK:-3 donors.

Blood transfusion utilization in hospitalized COVID-19 patients

Background

The acute respiratory illness designated coronavirus disease 2019 (COVID‐19) was first reported in Wuhan, China, in December 2019 and caused a worldwide pandemic. Concerns arose about the impact of the COVID‐19 pandemic on blood donations and potential significant blood transfusion needs in severely ill COVID‐19 patients. Data on blood usage in hospitalized COVID‐19 patients are scarce.

Study Design and Methods

We performed a retrospective observational study of blood component transfusions in the first 4 weeks of COVID‐19 ward admissions. The study period began 14 days before the first COVID‐19 cohort wards opened in our hospital in March 2020 and ended 28 days afterward. The number of patients and blood components transfused in the COVID‐19 wards was tabulated. Transfusion rates of each blood component were compared in COVID‐19 wards versus all other inpatient wards.

Results

COVID‐19 wards opened with seven suspected patients and after 4 weeks had 305 cumulative COVID‐19 admissions. Forty‐one of 305 hospitalized COVID‐19 patients (13.4%) received transfusions with 11.1% receiving red blood cells (RBCs), 1.6% platelets (PLTs), 1.0% plasma, and 1.0% cryoprecipitate (cryo). COVID‐19 wards had significantly lower transfusion rates compared to non‐COVID wards for RBCs (0.03 vs 0.08 units/patient‐day), PLTs (0.003 vs 0.033), and plasma (0.002 vs 0.018; all p < 0.0001). Cryo rates were similar (0.008 vs 0.009, p = 0.6).

Conclusions

Hospitalized COVID‐19 patients required many fewer blood transfusions than other hospitalized patients. COVID‐19 transfusion data will inform planning and preparation of blood resource utilization during the pandemic.

Passive Immunity for Coronavirus Disease 2019: A Commentary on Therapeutic Aspects Including Convalescent Plasma

In the ongoing pandemic of coronavirus disease 2019 (COVID-19), the novel virus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is infecting a naïve population. The innate immunity of the infected patient is unable to mount an effective defense, resulting in a severe illness with substantial morbidity and mortality. As most treatment modalities including antivirals and anti-inflammatory agents are mostly ineffective, an immunological approach is needed. The mechanism of innate immunity to this viral illness is not fully understood. Passive immunity becomes an important avenue for the management of these patients. In this article, the immune responses of COVID-19 patients are reviewed. As SARS-CoV-2 has many characteristics in common with two other viruses, SARS-CoV that cause severe acute respiratory syndrome (SARS) and MERS-CoV (Middle East respiratory syndrome coronavirus) that causes Middle East respiratory syndrome (MERS), the experiences learned from the use of passive immunity in treatment can be applied to COVID-19. The immune response includes the appearance of immunoglobulin M followed by immunoglobulin G and neutralizing antibodies. Convalescent plasma obtained from patients recovered from the illness with high titers of neutralizing antibodies was successful in treating many COVID-19 patients. The factors that determine responses as compared with those seen in SARS and MERS are also reviewed. As there are no approved vaccines against all three viruses, it remains a challenge in the ongoing development for an effective vaccine for COVID-19.

Blood transfusions in mass casualty events: recent trends

BACKGROUND AND OBJECTIVES

The US AABB disaster task force recommends estimating 3 RBC units per admission (UPA) for mass casualty events (MCEs). In a previous analysis, median MCE UPA were 2·7 RBCs, 1·2 plasmas and 0·27 platelet doses (Vox Sang 2017; 112:648). Additional recent data were sought from the current era of balanced massive transfusion protocols (bMTPs).

MATERIALS AND METHODS

Publications in English from 1980 to 2020 were reviewed for MCEs using ≥50 RBCs/event and with numbers of admissions available. MCE reports were stratified by era and event-wide or trauma-centre source. The bMTP era included all MCEs since 2010 plus a 2008 bMTP military report.

STATISTICS

Mann-Whitney test.

RESULTS

Thirty-two MCEs met analysis criteria. Event-wide reports used medians [interquartile ranges] of 1·8 [1·2-3·9] RBC, 0·6 [0·3-0·9] plasma and 0·14 [0·06-0·26] platelet-dose UPA. Trauma centres transfused 3·4 [2·7-6·3] RBC, 2·4 [1·3-4·1] plasma and 0·41 [0·34-0·50] platelet-dose UPA, all P < 0·05 vs event-wide. Same-event median post-day-1 transfusions were 50% of day-1 use for RBC, 28% for plasma and 16% for platelets. Compared to prior years, the median plasma/RBC transfusion ratio rose from 0·28 to 0·67 in the bMTP era (P < 0·01). In recent mass shootings, trauma centres transfused up to 42 platelets (range 0·45-0·57 UPA) on day 1.

CONCLUSION

Based on available mass casualty data, we recommend planning for 3 RBC, 1 plasma and one-fourth platelet-dose units per admission for blood centres (event-wide), and 6, 4 and one-half UPA, respectively, for trauma centres, which have seen rising plasma usage and large mass-shooting platelet needs.

Thrombosis Risk in Cancer Patients Receiving Red Blood Cell Transfusions

Patients with cancer have increased risk of thrombosis and often need red blood cell (RBC) transfusions. However, RBC transfusions may also promote thrombosis because of raised hematocrit and viscosity, storage-related RBC damage, and exposure to thrombogenic mediators from obsolescent RBCs. The authors conducted a literature survey for studies examining whether RBC transfusions were associated with increased risk of venous thromboembolism (VTE) in cancer patients. In perioperative cancer surgery patients with categorical comparisons of any versus no RBC transfusion, increased risk of VTE with RBC transfusion was found in 11 of 31 studies, 5 by univariate correlation only and 6 in multivariate analysis. All six multivariate-positive studies had intermediate overall rates of thrombosis (1.4–6.0%), and three were in urological surgery series. In the larger studies of > 2,000 patients (range: 2,219–44,656), the maximum odds ratio among the multivariate-positive studies was 1.3. Perioperative RBC transfusion volume was more strongly associated with VTE risk, with a positive association in six of seven studies. One large registry-based study of hospitalized cancer patients, not restricted to the perioperative setting, found an adjusted odds ratio of 1.60 (95% confidence interval: 1.53–1.67) for VTE risk in patients receiving RBCs compared with nontransfused patients.

Critical developments of 2018: A review of the literature from selected topics in transfusion. A committee report from the AABB's Clinical Transfusion Medicine Committee

BACKGROUND

The AABB compiles an annual synopsis of the published literature covering important developments in the field of transfusion medicine. An abridged version of this work is being made available in TRANSFUSION, with the full-length report available as Appendix S1 (available as supporting information in the online version of this paper).

STUDY DESIGN AND METHODS

Papers published in late 2017 and 2018 are included, as well as earlier papers cited for background. Although this synopsis is comprehensive, it is not exhaustive, and some papers may have been excluded or missed.

RESULTS

The following topics are covered: "big data" and "omics" studies, emerging infections and testing, platelet transfusion and pathogen reduction, transfusion therapy and coagulation, transfusion approach to hemorrhagic shock and mass casualties, therapeutic apheresis, and chimeric antigen receptor T-cell therapy.

CONCLUSION

This synopsis may be a useful educational tool.

Critical developments of 2017: a review of the literature from selected topics in transfusion. A committee report from the AABB Clinical Transfusion Medicine Committee

BACKGROUND

The AABB compiles an annual synopsis of the published literature covering important developments in the field of Transfusion Medicine. For the first time, an abridged version of this work is being made available in TRANSFUSION, with the full-length report available as an Appendix S1 (available as supporting information in the online version of this paper).

STUDY DESIGN AND METHODS

Papers published in 2016 and early 2017 are included, as well as earlier papers cited for background. Although this synopsis is comprehensive, it is not exhaustive, and some papers may have been excluded or missed.

RESULTS

The following topics are covered: duration of red blood cell storage and clinical outcomes, blood donor characteristics and patient outcomes, reversal of bleeding in hemophilia and for patients on direct oral anticoagulants, transfusion approach to hemorrhagic shock, pathogen inactivation, pediatric transfusion medicine, therapeutic apheresis, and extracorporeal support.

CONCLUSION

This synopsis may be a useful educational tool.

Blood component transfusions in mass casualty events

BACKGROUND AND OBJECTIVES

Planning transfusion needs in mass casualty events (MCE) is critical for disaster preparedness. Published data on blood component usage were analysed to seek correlative factors and usage rates.

MATERIALS AND METHODS

English-language medical publications since 1980 were searched for MCEs with numbers of patient admissions and transfused RBCs. Reports were excluded from natural disasters or with total RBC use <50 units. Statistical analysis employed Mann-Whitney U-tests and Spearman's rank correlations.

RESULTS

In 24 reports, the average units per admission were 3·06 RBCs, 2·13 plasmas and 0·37 platelet doses. Five RBCs per admission would have sufficed for 87% of events. Transfusion needs involving bombings correlated with admissions (P ≤ 0·03). In the formula (massive-transfusion patients in MCE) times X = (total units for all MCE patients), the average X was 35 for RBCs (correlation P = 0·01), 17 for plasma (P = 0·10) and five for platelet doses (P = 0·06). From 67% to 84% of all components used were given in the first 24 h (event medians).

CONCLUSIONS

Blood component use in MCEs correlated with numbers of patients admitted or receiving massive transfusion. More current data are needed to better reflect emerging trauma care practices and refine predictive models of transfusion needs.

Appropriateness of Plasma Transfusion: A College of American Pathologists Q-Probes Study of Guidelines, Waste, and Serious Adverse Events

Context.—

Plasma transfusion guidelines support patient care and safety, management of product wastage, and compliance; yet, there is little information across multiple institutions about use of and adherence to plasma transfusion guidelines.

Objective.—

To survey multiple institutions regarding their plasma transfusion guidelines and compliance, plasma wastage rates, and incidence of transfusion reactions associated with plasma transfusion.

Design.—

The College of American Pathologists Q-Probes model was used to collect data from 89 participating institutions. Each site was asked to provide data relevant to its most recent 40 adult patient plasma transfusion episodes, and complete a questionnaire regarding plasma transfusion guidelines, utilization and wastage of plasma, and transfusion reactions related to plasma transfusion.

Results.—

The participating institutions reported a total of 3383 evaluable plasma transfusion episodes with transfusion of 9060 units of plasma. Compliance with institution-specific guidelines was seen in 3018 events (89%). Pretransfusion and posttransfusion coagulation testing was done in 3281 (97%) and 3043 (90%) of these episodes, respectively. Inappropriate criteria were noted for more than 100 transfusion episodes. Thirty-two plasma transfusion episodes (1%) were associated with a transfusion reaction. Serious and fatal reactions were reported. Median plasma wastage rate for the year preceding the study was 4.5%.

Conclusions.—

Most participating institutions are compliant with plasma transfusion guidelines based on published references, supported by appropriate testing. With transfusions for indications that lack evidence of efficacy and incidence of transfusion reactions, there is an ongoing role for transfusion service leaders to continue to update and monitor plasma transfusion practices.

Blood Bank Specimen Mislabeling: A College of American Pathologists Q-Probes Study of 41 333 Blood Bank Specimens in 30 Institutions

Context.—Incorrectly labeled patient blood specimens create opportunities for laboratory testing personnel to mistake one patient's specimen for a specimen from a different patient. Transfusion of blood that is typed on specimens that are mislabeled can result in acute hemolytic transfusion reactions.

Objective.—To assess the rates of blood bank ABO typing specimens that are mislabeled and/or contain blood belonging to another patient (so-called wrong blood in tube [WBIT]), and to compare these rates with those determined in a similar study performed in 2007.

Design.—Participants enrolled in this College of American Pathologists Q-Probes study for the first quarter of 2015 tallied the number of mislabeled and WBIT ABO blood typing specimens. Outcome measurements were the number of mislabeled and WBIT instances per 1000 specimens. We also evaluated the effects of various practice characteristics, in particular the use of bar coding, on the outcome measurements.

Results.—A total of 30 institutions submitting data on 41 333 ABO blood typing specimens recorded aggregate rates of 7.4 instances of mislabeling (306 specimens) and 0.43 instances of WBIT (10 of 23 234) per 1000 specimens submitted. Mislabeling rates were lower in institutions requiring that specimens be labeled with patients' birth dates than those that did not. The rates of specimen mislabeling and WBIT were otherwise unassociated with any of the other practice variables evaluated.

Conclusions.—The rates of ABO blood typing specimen mislabeling and WBIT are not statistically different from those determined in a similar study performed in 2007 (P = .94 and P = .10). The use of bar coding was not associated with lower mislabeling (P = .80) or WBIT rates (P = .79).

Clinical Practice Guidelines From the AABB: Red Blood Cell Transfusion Thresholds and Storage

IMPORTANCE

More than 100 million units of blood are collected worldwide each year, yet the indication for red blood cell (RBC) transfusion and the optimal length of RBC storage prior to transfusion are uncertain.

OBJECTIVE

To provide recommendations for the target hemoglobin level for RBC transfusion among hospitalized adult patients who are hemodynamically stable and the length of time RBCs should be stored prior to transfusion.

EVIDENCE REVIEW

Reference librarians conducted a literature search for randomized clinical trials (RCTs) evaluating hemoglobin thresholds for RBC transfusion (1950-May 2016) and RBC storage duration (1948-May 2016) without language restrictions. The results were summarized using the Grading of Recommendations Assessment, Development and Evaluation method. For RBC transfusion thresholds, 31 RCTs included 12 587 participants and compared restrictive thresholds (transfusion not indicated until the hemoglobin level is 7-8 g/dL) with liberal thresholds (transfusion not indicated until the hemoglobin level is 9-10 g/dL). The summary estimates across trials demonstrated that restrictive RBC transfusion thresholds were not associated with higher rates of adverse clinical outcomes, including 30-day mortality, myocardial infarction, cerebrovascular accident, rebleeding, pneumonia, or thromboembolism. For RBC storage duration, 13 RCTs included 5515 participants randomly allocated to receive fresher blood or standard-issue blood. These RCTs demonstrated that fresher blood did not improve clinical outcomes.

FINDINGS

It is good practice to consider the hemoglobin level, the overall clinical context, patient preferences, and alternative therapies when making transfusion decisions regarding an individual patient. Recommendation 1: a restrictive RBC transfusion threshold in which the transfusion is not indicated until the hemoglobin level is 7 g/dL is recommended for hospitalized adult patients who are hemodynamically stable, including critically ill patients, rather than when the hemoglobin level is 10 g/dL (strong recommendation, moderate quality evidence). A restrictive RBC transfusion threshold of 8 g/dL is recommended for patients undergoing orthopedic surgery, cardiac surgery, and those with preexisting cardiovascular disease (strong recommendation, moderate quality evidence). The restrictive transfusion threshold of 7 g/dL is likely comparable with 8 g/dL, but RCT evidence is not available for all patient categories. These recommendations do not apply to patients with acute coronary syndrome, severe thrombocytopenia (patients treated for hematological or oncological reasons who are at risk of bleeding), and chronic transfusion-dependent anemia (not recommended due to insufficient evidence). Recommendation 2: patients, including neonates, should receive RBC units selected at any point within their licensed dating period (standard issue) rather than limiting patients to transfusion of only fresh (storage length: <10 days) RBC units (strong recommendation, moderate quality evidence).

CONCLUSIONS AND RELEVANCE

Research in RBC transfusion medicine has significantly advanced the science in recent years and provides high-quality evidence to inform guidelines. A restrictive transfusion threshold is safe in most clinical settings and the current blood banking practices of using standard-issue blood should be continued.

A Caucasian JK*A/JK*B woman with Jk(a+b-) red blood cells, anti-Jkb, and a novel JK*B allele c.1038delG

The Kidd blood group on the red blood cell (RBC) glycoprotein urea transporter-B has a growing number of weak and null alleles in its gene SLC14A1 that are emerging from more widespread genotyping of blood donors and patients. We investigated a 64-year-old Caucasian woman of Polish-Czech descent who developed anti-Jkb detected in solid-phase RBC adherence testing within 12 days after 7 units of RBCs were transfused. Her RBCs subsequently typed Jk(a+b–) by licensed reagents and human antisera. Nevertheless, in RBC genotyping (BioArray HEA BeadChip, Immucor, Warren, NJ) performed in our transfusion service on all patients with alloantibodies, her Kidd typing was JK*A/JK*B based on the Jka/Jkb single nucleotide polymorphism in exon 9 (c.838G>A, p.Asp280Asn). Genomic analysis and cDNA sequencing of her JK*B allele revealed a novel single-nucleotide deletion of c.1038G in exon 11, predicting a frameshift and premature stop (p.Thr346Thrfs*5) after translation of nearly 90 percent of the expressed exons 4–11. This allele has been provisionally named JK*02N.14, subject to approval by the International Society of Blood Transfusion Working Party. The site of this variant is closer to the C-terminus than that of any allele associated with the Jk(a–b–) phenotype reported to date. Routine genotyping of patients with RBC alloantibodies can reveal variants posing potential risk of alloimmunization. Continuing investigation of Kidd variants may shed light on the structure of Kidd antigens and the function of urea transporter-B.

Hemostatic Efficacy of Pathogen-Inactivated Blood Components

Pathogen inactivation (PI), or pathogen reduction technology, reduces the infectious risk of plasma and platelet transfusions, and also affects clotting factor activities and platelet viabilities. Plasma is treated with solvent-detergent to disrupt enveloped viruses, or with photoactive agents methylene blue plus light, or amotosalen (AM) or riboflavin (RF) plus ultraviolet (UV) light, to disrupt pathogen nucleic acids. PI plasmas have average clotting factor activities of 75 to 85% of untreated plasma. PI plasmas are generally equivalent to regular plasma in randomized clinical trials (RCTs) in regard to coagulation test corrections and bleeding outcomes, except for one trial in which RF plasma was inferior for prothrombin time correction. Platelets are treated with UV plus RF or AM. In RCTs, the mean 1-hour corrected count increments from PI platelets are 66 to 94% (trials median, 75%) of those from untreated platelets. PI platelets also have lifespans of 4 to 5 days after 5 days of storage, compared with 6 to 7 days for untreated platelets. Bleeding outcomes comparing PI versus non-PI platelets in RCTs have been equivalent, except one study with more bleeding on AM platelets. Platelet treatment with UVC light alone for PI has entered clinical trials.

Alloimmunization in sickle cell anemia in the era of extended red cell typing

BACKGROUND

Red blood cell (RBC) transfusion remains an essential part of the management of patients with sickle cell disease (SCD). Alloimmunization is a major complication of transfusions. Extended RBC typing is advocated as a means to reduce alloimmunization in SCD. Our goal was to assess alloimmunization among individuals with SCD at our center since implementing extended RBC typing.

MATERIALS AND METHODS

We reviewed electronic medical records of all patients with SCD (N = 641) in our comprehensive SCD Program to determine transfusion histories. Cross-referencing with our blood bank database, we extracted data such as antibodies identified, detection date and genotyping in specific cases. Transfusion sources were determined for those with C, E, and Kell antibodies.

RESULTS

Of 180 patients transfused from 2002 to 2011, 26 developed at least one new antibody. The majority of alloimmunized patients (14/26) received episodic transfusions only. The most common antibodies formed were against C and E antigens. Of the 16 patients who developed C, E, Kell antibodies, nine had one or more documented transfusions at an outside hospital. Five patients had Rh variants undetectable on routine phenotyping including two novel e alleles related to ceAR and ce(S)(733G).

CONCLUSION

Despite extended RBC typing, alloimmunization may still occur due to RBC variants that are not detected on routine screening and transfusions at institutions where extended RBC typing is not done. Extended RBC typing should be the standard of care for patients with SCD. Prospective genotyping may reduce allosensitization to rare variants not detected on routine screening.

Blood component recalls and market withdrawals: frequency, reasons, and management in the United States

In a previous article, we reviewed the management of blood component recalls and withdrawals (G. Ramsey. Transfusion Med Rev 2004;18:36-45). Since then, US rates of recall and biological product deviation for blood components have improved significantly, particularly with regard to reduced recalls for donor infectious disease risks or testing. However, analysis of the current data from the US Food and Drug Administration suggests that 1 (0.4%) in 250 blood components is involved in market withdrawals and quarantines, with 1 in 5800 components formally recalled. Most of these units, unfortunately, had already have been transfused. The U.S. Food and Drug Administration has issued several recent guidances that address transfusion service actions for dealing with specific infectious disease problems. This present article updates our 2004 recommendations as to when to notify physicians about transfused nonconforming blood components.

Red blood cell products: consideration of the discrepant temperature ranges permitted for storage versus transport

The focus of this study was to determine if there is significant data to prohibit short-term storage of red blood cells (RBCs; i.e., <24 hr) at 1 to 10°C rather than 1 to 6°C, which occurs not uncommonly when RBCs are stored in a cooler for a patient during surgery. This document will describe the evidence in the literature to date regarding the potential impact of having RBCs temporarily in the 1 to 10°C range versus in the 1 to 6°C range, if any, on key measures of the quality of RBC storage: potassium, adenosine triphosphate, 2,3-diphosphoglycerate, posttransfusion survival, and bacterial contamination.

Approaches to minimize infection risk in blood banking and transfusion practice

The use of blood donor history and state-of-the-art FDA-licensed serological and nucleic acid testing (NAT) assays have greatly reduced the "infectious window" for several transfusion-transmitted pathogens. Currently transmission of human immunodeficiency virus (HIV), Human T-cell Lymphotropic Virus (HTLV), hepatitis viruses and West Nile Virus are rare events. The seroprevalence of cytomegalovirus in the donor population is high and cytomegalovirus infection can cause significant complications for immunocompromised recipients of blood transfusion. Careful use of CMV seronegative blood resources and leukoreduction of blood products are able to prevent most CMV infections in these patients. Currently, bacterial contamination of platelet concentrates is the greatest remaining infectious disease risk in blood transfusion. Specialized donor collection procedures reduce the risk of bacterial contamination of blood products; blood culture and surrogate testing procedures are used to detect potential bacterially contaminated platelet products prior to transfusion. A rapid quantitative immunoassay is now available to test for the presence of lipotechoic acid and lipopolysaccharide bacterial products prior to platelet transfusion. Attention has now turned to emerging infectious diseases including variant Creutzfeldt-Jakob disease, dengue, babesiosis, Chagas' disease and malaria. Challenges are presented to identify and prevent transmission of these agents. Several methods are being used or in development to reduce infectivity of blood products, including solvent-detergent processing of plasma and nucleic acid cross-linking via photochemical reactions with methylene blue, riboflavin, psoralen and alkylating agents. Several opportunities exist to further improve blood safety through advances in infectious disease screening and pathogen inactivation methods.

Morphometry and abnormalities of the feet of Kaimanawa feral horses in New Zealand

OBJECTIVE

The present study investigated the foot health of the Kaimanawa feral horse population and tested the hypotheses that horses would have a large range of foot morphology and that the incidence of foot abnormality would be significantly high.

PROCEDURES

Abnormality was defined as a variation from what the two veterinarian assessors considered as optimal morphology and which was considered to impact negatively on the structure and/or function of the foot. Fifteen morphometric variables were measured on four calibrated photographic views of all four feet of 20 adult Kaimanawa feral horses. Four morphometric variables were measured from the lateromedial radiographs of the left forefoot of each horse. In addition, the study identified the incidence of gross abnormality observed on the photographs and radiographs of all 80 feet.

RESULTS

There was a large variation between horses in the morphometric dimensions, indicating an inconsistent foot type. Mean hoof variables were outside the normal range recommended by veterinarians and hoof care providers; 35% of all feet had a long toe conformation and 15% had a mediolateral imbalance. Abnormalities included lateral (85% of horses) and dorsal (90% of horses) wall flares, presence of laminar rings (80% of horses) and bull-nose tip of the distal phalanx (75% of horses). Both hypotheses were therefore accepted.

CONCLUSIONS

The Kaimanawa feral horse population demonstrated a broad range of foot abnormalities and we propose that one reason for the questionable foot health and conformation is lack of abrasive wearing by the environment. In comparison with other feral horse populations in Australia and America there may be less pressure on the natural selection of the foot of the Kaimanawa horses by the forgiving environment of the Kaimanawa Ranges. Contrary to popular belief, the feral horse foot type should not be used as an ideal model for the domestic horse foot.

Inaccurate doses of R immune globulin after rh-incompatible fetomaternal hemorrhage: survey of laboratory practice

CONTEXT

Rh(D)-negative women with a large fetomaternal hemorrhage (FMH) from an Rh(D)-positive fetus are at risk for anti-D alloimmunization if they do not receive adequate Rh immune globulin (RhIG). Determination of the adequate RhIG dose for these women is a critical laboratory procedure for protecting their future Rh(D)-positive children.

OBJECTIVE

To determine how often laboratories recommended an inaccurate dose of RhIG for excess FMH.

DESIGN

Nearly 1600 laboratories using the College of American Pathologists' proficiency testing for fetal red blood cell detection were surveyed to determine (1) their calculation method and (2) the number of RhIG doses recommended for a survey specimen, based on their measured percentage of fetal red blood cells. We surveyed nearly 1450 laboratories for their accuracy in determining RhIG dose, using 2 common calculation methods we provided.

RESULTS

The AABB Technical Manual method was used by 67% of responding laboratories. However, 20.7% of laboratories using this method would have recommended an inaccurate dose of RhIG--11.5% too much and 9.2% too little--for the level of FMH reported in the survey specimen. If all laboratories had used the common recommendation of 300 microg/30 mL of fetal blood present, 2% would have recommended RhIG doses too low for the volume of FMH they measured. In 3 of the 4 calculation exercises we provided, 20% to 30% of laboratories underestimated the necessary dose of RhIG.

CONCLUSIONS

Based on our surveys, some mothers with excess FMH may be receiving inaccurate doses of RhIG. Laboratories performing quantification of FMH should review their procedures and training for calculating RhIG dosage.

Catastrophic multiple organ ischemia due to an anti-Pr cold agglutinin developing in a patient with mixed cryoglobulinemia after treatment with rituximab

Cold agglutinin disease occurring with cryoglobulinemia is a rare occurrence. Here, we report a patient with mixed cryoglobulinemia that was treated with rituximab and, after response, developed an anti-Pr cold agglutinin that manifested with hemolysis and microvascular occlusion causing mesenteric ischemia and cerebral infarction. Unlike previous reports of patients with cryoglobulinemia and cold agglutinin disease, our patient did not have a detectable cryoprecipitate when his cold agglutinin manifested.

Legal, financial, and public health consequences of transfusion-transmitted hepatitis C virus in persons with haemophilia

BACKGROUND

Since the first cases of acquired immunodeficiency syndrome in persons with haemophilia were reported in 1982, much has been written about the consequences of human immunodeficiency virus (HIV) contamination of the blood supply. Relatively little attention has been paid to similar hepatitis C virus (HCV) concerns since the first cases of HCV-infected persons with haemophilia were identified in 1989.

METHODS

We review the history, public health, policy, and financial consequences of blood supply policy decisions made for persons with haemophilia who received HCV-contaminated blood products in eight countries that were severely impacted by viral contamination of the blood supply during the 1980s, contrasting these findings with those reported previously for HIV contamination of the blood supply during the same time-period. A Medline search and a hand search of retrieved bibliographies of English-language articles on HCV concerns in haemophilia patients published from 1989 to 2006 were performed.

RESULTS

Our review identified that two- to eightfold more persons with haemophilia in the eight countries contracted HCV vs. HIV from contaminated blood products during the 1980s. Opportunistic infections and immunosuppression-related complications among persons with haemophilia developed shortly after these patients received HIV-infected blood products whereas hepatic complications among HCV-infected persons with haemophilia are just now being diagnosed two decades after these individuals received HCV-contaminated blood products. Policy makers in four countries conducted official public inquiries into blood safety decisions related to HIV- and/or HCV-contamination of the blood supply. More than 20 countries allocated compensation funds for HIV-infected persons with haemophilia (mean award ranging from $37 000 to 400 000) whereas only the UK, Canada, and Ireland allocated compensation funds for HCV-infected persons with haemophilia (mean award ranging from $37 000 to 50 000).

CONCLUSION

While the clinical impact among persons with haemophilia of HCV contamination of the blood supply in the 1980s was larger than the impact of HIV contamination of the blood supply during this time-period, the policy response was smaller. Consideration should be given to adopting support programmes for HCV-infected persons with haemophilia in countries that do not have these programs.

Treating coagulopathy in liver disease with plasma transfusions or recombinant factor VIIa: an evidence-based review

In severe liver disease, poor synthetic function leads to characteristic deficiencies in numerous coagulation factors, and plasma transfusions are frequently administered to treat or prevent bleeding. This chapter reviews the available English-language randomized controlled trials, evidence-based practice guidelines, and observational studies relevant to establishing criteria for plasma transfusions in liver disease. The alternatives of pathogen-inactivated plasmas and recombinant factor VIIa were also reviewed from this perspective. In current guidelines, plasma transfusions are justified when haemostasis is needed for bleeding or invasive procedures, and the prothrombin time (PT) or partial thromboplastin time (PTT) is >1.5 times normal (mid-normal or, for PTT, sometimes upper limit). Conversion of the PT to the International Normalized Ratio has not been validated in liver disease. Solvent-detergent or methylene-blue treatments alter various clotting factors, which might affect efficacy in liver disease. Recombinant factor VIIa improves laboratory clotting measurements, but reduction of bleeding is less well established to date.

Managing recalls and withdrawals of blood components

Donor centers are issuing a growing number of recalls and market withdrawals to hospital transfusion services about blood components. More than 1 in 2,000 units were recalled in the late 1990s in the United States. The most common reason for these notices from donor centers is postdonation donor information. Most of these units had been transfused, and many present a “risk of a risk” (ie, a problem might have been present that might have affected the recipient). A few regulations and standards address recalls in general terms, but transfusion services generally have wide discretion in the management of specific common recall problems. The Food and Drug Administration (FDA) is now including posttransfusion evaluations in its guidelines for emerging infectious threats to the blood supply. We suggest that hospital transfusion services should have standard operating procedures for managing recalls and that the hospital transfusion committee and the quality management program should provide local input or oversight. Using the FDA’s categories of donor center biological product deviations, we provide recommendations to consider for when to notify the recipient’s physician, after postdonation information is received about a previously transfused blood component. More study of this important everyday issue in transfusion medicine is highly desirable.

CD34(+) cell collection efficiency does not correlate with the pre-leukapheresis hematocrit

One hundred and seventy-seven large-volume leukapheresis procedures performed on 91 patients over a 15 month period were reviewed to see if the pre-apheresis hematocrit (Hct) affected the CD34(+) cell collection efficiency (CE) of the Fenwal CS 3000 Plus cell separator. The Hct was 0.174-0.461 (median 0.317), and the peripheral blood CD34(+) cell count 2-2487 per microl (median 21). The total CD34(+) cell quantity collected was 3.0-2677.2 x 10(6) (median 113.0). Based on the number of CD34(+)cells contained in the blood volume processed (23.3-37303.2 x 10(6); median 318.0), the CE was 1.7-87.5% (median 30.3). No correlation was found between the Hct and CE (r(2) = 0.0034; P = 0.44) or the total CD34(+) cell quantity collected (r2 = 0.0040; P = 0.40). CEs for Hct <0.25 (median CE 36%), Hct 0.25-0.299 (median CE 30%) and Hct 0.30 (median CE 30%) were comparable. As expected, highly significant correlations were seen between the CD34(+) cell quantities collected and quantities processed (r2 = 0.59; P < 10(-6)) as well as the peripheral blood CD34(+) cell counts (r2= 0.60; P < 10(-6)). We conclude that the minimum acceptable Hct or hemoglobin level for leukapheresis should be dictated by clinical circumstances because it does not affect stem cell collection.

Decision-making capacity to execute a health care proxy: development and testing of guidelines

OBJECTIVE

To evaluate the reliability and validity of guidelines to determine the capacity of nursing home residents to execute a health care proxy (HCP).

DESIGN

A cross-sectional study.

SETTING

A 750-bed not-for-profit nursing home located in New York City.

PARTICIPANTS

A random sample of 200 nursing home residents: average age, 87; 99% white; 83% female; average length of stay, 3.05 years; mean Mini-Mental State Exam (MMSE) score, 15.9.

MEASUREMENTS

Demographic characteristics (Minimum Data Set (MDS)); function and cognitive status (Institutional Comprehensive Assessment and Referral Evaluation (INCARE)); Reisberg Dementia Staging; MMSE; Minimum Data Set-Cognitive Performance Scale (MDS-COGS)); an investigator-developed measure of a nursing home resident's capacity to execute a health care proxy (Health Care Proxy (HCP) Guidelines.)

RESULTS

The internal consistency of the decision-making scales in the HCP Guidelines, paraphrased recall and recognition, reached acceptable levels, alphas of .85 and .73, respectively. Interrater reliability estimates were .92 and .94, respectively, for the recall and recognition scales; test-retest reliability estimates were .83 and .90. The discriminant validity of these scales is promising. For example, the MMSE correlation was .51 with the Recall scale and .57 with the Recognition scale. Of residents with severe cognitive impairment (MMSE < 10), 71% completed 50% or more of the scaled items in the HCP guidelines and 95% consistently named a proxy.

CONCLUSIONS

Seventy-three percent of testable residents, approximately three-quarters of whom were cognitively impaired, evidenced sufficient capacity to execute an HCP. Of residents with severe cognitive impairment, the HCP guidelines are potentially useful in identifying those with the capacity to execute a HCP. The guidelines are more predictive than the MMSE in identifying residents able to execute a HCP.

Blood component recalls in the United States

BACKGROUND

United States blood suppliers are required to recall marketed blood components later found to be in violation of Food and Drug Administration (FDA) regulations for safety, purity, and potency. Many recalled units have already been transfused. Analysis of the frequency and nature of blood component recalls would be useful for blood suppliers, transfusion services, and physicians.

STUDY DESIGN AND METHODS

Each blood component recall in the weekly FDA Enforcement Report from 1990 through 1997 was examined for the number of units, recall reason, and hazard class. Units for manufacturing were excluded.

RESULTS

In 8 years, an estimated 241,800 blood components were recalled, or approximately 1 in 700 units available to US hospitals. Eighty-eight percent of recalled units were in 22 large recalls of over 1000 units each. The most common reasons were incorrect testing for syphilis (57% of units) or viral markers (19%), reactive or previously reactive donor viral markers (6-11%), and inadequate donor-history screening (4%). Twelve units were in the FDA's highest hazard Class I, 24 percent were in Class II, and 76 percent were in Class III. Over 43,900 units had HIV-related problems, but only 3 units involved HIV transmission. Large recalls have declined since peaking in 1995, but units in small recalls increased 116 percent in 1997 over the previous 7-year average.

CONCLUSIONS

Although high-risk recalls are rare, many blood component recalls pose medical concerns for physicians and patients. The recent decline in large recalls may be due to increased FDA oversight, stricter accreditation standards for quality improvement, and more centralized donor testing in large specialized laboratories. However, smaller recalls, which involve nearly all blood suppliers, were sharply higher in 1997.

Hematopoietic growth factors and transfusion medicine

At least 20 different hematopoietic drugs (see Table 1) are currently under investigation. These most likely will impact on all aspects of transfusion therapy. Which agents to use and in what combinations will be the subject of scrutiny for many years to come as scientists try to recreate and enhance the process of hematopoiesis. Perhaps someday blood cells and hematopoietic progenitor cells can be manufactured for therapy with genetically selected phenotypes to avoid immune destruction and rejection. If this comes to pass, blood donations as we know them today, as a valuable adjunct to medical care, will fade into history, supplanted by the use of hematopoietic growth factors.

Implementation of the Patient Self-Determination Act (PSDA) in nursing homes in New York City

OBJECTIVE

To examine implementation of the Patient Self Determination Act (PSDA), verbal directives, procedures for determination of resident' decision-making capacity, and role of ethics committees in nursing homes in New York City.

DESIGN

Telephone survey.

PARTICIPANTS

Social workers in 109 (69%) nursing homes in New York City.

MEASUREMENT

An 80-item instrument addressing: (1) social worker knowledge of the PSDA; (2) informing residents about advance directives (living wills and durable power of attorney for health care [health care proxies]); (3) determination of decision-making capacity to be informed about advance directives; (4) estimates of advance directives executed; (5) perceptions of PSDA effect; (6) ethics committees; (7) follow-up and documentation; and (8) staff and community education.

MAIN RESULTS

Virtually all social workers in nursing homes stated that they made what they perceived to be a "serious effort" to inform residents about advance directives and to have residents execute directives (preferentially a health care proxy). More residents were thought to have executed a directive pursuant to the PSDA law than before the Act went into effect. Social workers in most homes informed residents about directives through face-to-face discussions. Most homes, however, did not inform residents who were thought to lack decision-making capacity about their right to execute a directive. Only 37% of homes had written procedures to determine a resident's decision-making capacity to be informed about directives; most homes relied on physician and social work assessments. Voluntary homes differed significantly from proprietary homes in that they were larger, more likely to have an ethics committee, and more aggressive in their implementation of the PSDA. Forty-five percent of homes with an ethics committee had written procedures for determination of resident decision-making capacity compared with 26% of homes without a committee. Overall, 24% of residents were thought to have executed an advance directive. The number of directives per bed did not vary significantly by facility size, ownership, religious affiliation, or whether they did or did not have an ethics committee.

CONCLUSIONS

The fact that social workers in nursing homes speak with most residents about advance directives has the potential to improve resident understanding around end of life decisions. The practice of not informing residents about advance directives when they are perceived to lack decision-making capacity is problematic given that most homes have no clear procedures for determining residents' cognitive capacity to execute a directive. There is a need to replicate the benefits achieved by homes with ethics committees in implementing the PSDA in other homes.