Hemovigilance is an essential part of the transfusion process and is defined as surveillance procedures covering the whole transfusion chain, from collection of blood and its components, intended to collect and assess information on unexpected or undesirable effects resulting from the therapeutic use of labile blood products and to prevent their occurrence or recurrence. The UK surveillance scheme has collected data for 16 years and is a model demonstrating how information on adverse incidents can be used to improve patient safety, influencing the management of donors and improved education and training for the many people involved in the transfusion process.
Key points
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Transfusion is very safe with a low risk of viral or other infection; the most common pathologic event is a febrile/allergic transfusion reaction.
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Adverse event reporting (hemovigilance) has resulted in changes in transfusion practice, which have reduced pathologic events such as transfusion-related acute lung injury.
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Errors in basic procedures have been identified as the most common cause of adverse transfusion incidents (correct identification of the patient is essential).
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Every transfusion should be assessed for appropriateness to avoid unnecessary exposure to blood components.
Questions about the safety of transfusion arose in the 1980s and 1990s with evidence of transmission of hepatitis viruses and the emergence of human immunodeficiency virus (HIV) in the blood supply. People with hemophilia were particularly susceptible because factor concentrates were manufactured from pools of plasma containing up to 20,000 donations, and hepatitis transmission was suspected soon after their introduction. Transfusion-transmission of acquired immunodeficiency was recognized in 1983 when a 14-month-old infant developed unusual infections; this child had been transfused with blood from a donor who, although well at the time of donation, had subsequently died of acquired immunodeficiency. Transfusion-transmission was soon confirmed in several other cases. Screening of blood donations for HIV started in 1985. Fortunately, the steps taken by Blood Centers, a combination of donor exclusion together with viral screening of donations, have been very effective. The residual risk of HIV and hepatitis C virus among all allogeneic donations in the United States is currently less than 1 per 1 million donations. Only 20 HIV transmissions have occurred in the United States since 1988, the most recent in 2008. The risk of viral infection is now very low, and most recent estimates in the United Kingdom are shown in Table 1 .
| Agent | Risk Per Million Donations (95% Confidence Interval) |
|---|---|
| Hepatitis B | 0.76 (0.22–1.61) |
| Hepatitis C | 0.036 (0.015–0.07) |
| HIV | 0.15 (0.09–0.32) |
At that time there was no systematic surveillance of blood transfusion recipients for these infections or other complications of transfusion. Continued surveillance of infections in the blood supply is very important as shown by the emergence of West Nile virus and other agents. Different countries have different mechanisms and policies for surveillance. Some transfusion specialists were also concerned that there was no surveillance for other adverse outcomes or errors such as wrong transfusions. A survey of 400 UK hematology departments reported 111 wrong blood incidents (6 deaths and 12 instances of major morbidity due to ABO incompatibility) from 245 respondents, and the authors recommended setting up a national reporting scheme. Hence, hemovigilance was born.
Hemovigilance: definition
Surveillance procedures cover the whole transfusion chain, from collection of blood and its components, intended to collect and assess information on unexpected or undesirable effects resulting from the therapeutic use of labile blood products and to prevent their occurrence or recurrence (International Society of Blood Transfusion).
Hemovigilance is a recent addition to transfusion practice. National programs were developed in several European countries, most notably in France from 1991 and the United Kingdom in 1996. The UK system is described as a model of hemovigilance to demonstrate the benefits of hemovigilance. In addition, the UK system is unique in reporting data from pediatric transfusion. Although overall most transfusion recipients are older adults, premature infants are a particularly highly transfused group with a long life expectancy.
In the United States, the Food and Drug Administration requires reporting of serious adverse reactions and deaths. Between 2008 and 2012, 200 deaths were reported. The Center for Disease Control has developed a national reporting scheme with Internet-based entry (a Hemovigilance Module in the National Healthcare Safety Network). This reporting system is voluntary and anonymous; by 2012 more than 140 institutions had enrolled, but this probably reflects surveillance of less than 5% of transfusions. Baseline data collected by the most recently reported National Blood Collection and Utilization Survey (NBCUS) for 2008 in the United States suggested that the reported adverse reaction rate was 2.6 events per 1000 units transfused compared with 3 to 7 events in other national schemes, suggesting underreporting. Pediatric transfusions made up 2.6% of all red cell transfusions in this NBCUS.
In Europe, data collection is mandated by European Union law since 2002 and this has driven the development of several national systems. A recent review noted wide variations in data quality assurance and that it is therefore difficult to make comparisons between countries.
Hemovigilance: definition
Surveillance procedures cover the whole transfusion chain, from collection of blood and its components, intended to collect and assess information on unexpected or undesirable effects resulting from the therapeutic use of labile blood products and to prevent their occurrence or recurrence (International Society of Blood Transfusion).
Hemovigilance is a recent addition to transfusion practice. National programs were developed in several European countries, most notably in France from 1991 and the United Kingdom in 1996. The UK system is described as a model of hemovigilance to demonstrate the benefits of hemovigilance. In addition, the UK system is unique in reporting data from pediatric transfusion. Although overall most transfusion recipients are older adults, premature infants are a particularly highly transfused group with a long life expectancy.
In the United States, the Food and Drug Administration requires reporting of serious adverse reactions and deaths. Between 2008 and 2012, 200 deaths were reported. The Center for Disease Control has developed a national reporting scheme with Internet-based entry (a Hemovigilance Module in the National Healthcare Safety Network). This reporting system is voluntary and anonymous; by 2012 more than 140 institutions had enrolled, but this probably reflects surveillance of less than 5% of transfusions. Baseline data collected by the most recently reported National Blood Collection and Utilization Survey (NBCUS) for 2008 in the United States suggested that the reported adverse reaction rate was 2.6 events per 1000 units transfused compared with 3 to 7 events in other national schemes, suggesting underreporting. Pediatric transfusions made up 2.6% of all red cell transfusions in this NBCUS.
In Europe, data collection is mandated by European Union law since 2002 and this has driven the development of several national systems. A recent review noted wide variations in data quality assurance and that it is therefore difficult to make comparisons between countries.
Hemovigilance: aims
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To identify trends in adverse reactions and events
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To inform transfusion policy
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To target areas for improved practice
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To stimulate research
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To raise awareness of transfusion hazards
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To provide early warning of new complications
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To improve transfusion safety for patients
The UK hemovigilance scheme, Serious Hazards of Transfusion (SHOT), was launched in 1996, funded by the UK blood services. All UK National Health Service hospitals were invited to register for participation. Definitions of what to report have been refined over the 16 years of reporting ( Table 2 ) and are comparable to those of the International Society of Blood Transfusion. The reporting categories can be divided into pathologic reactions and those caused by error that should be completely preventable. Some pathologic incidents are probably preventable by better pretransfusion assessment and better monitoring (eg, some instances of transfusion-associated circulatory overload, and some hemolytic transfusion reactions by better selection of red cells). SHOT does not collect donor events.
| Group | Category |
|---|---|
| Pathologic incidents | Acute transfusion reactions (allergic, hypotensive, severe febrile) Hemolytic transfusion reactions (immediate or delayed) Transfusion-associated graft vs host disease Transfusion-related acute lung injury (TRALI) Posttransfusion purpura Transfusion-associated circulatory overload Transfusion-associated dyspnea Transfusion-transmitted infection Autologous transfusion or cell salvage incidents Uncategorized complications of transfusion |
| Incidents resulting from errors | Incorrect blood component transfused (wrong component or without specific requirements such as CMV negative or irradiated) Handling and storage errors (eg, out of cold storage for too long, or transfused over more than 4 h) Incidents where a patient received the right component but where one or more errors were made Inappropriate, unnecessary, or delayed transfusions (eg, transfused for iron deficiency, avoidable use of emergency O RhD negative units) Reporting errors in the administration of anti-D immunoglobulin to women during and after pregnancy |
| Incidents where no harm was done but from which lessons can be learned | Near miss events |
In the first year (1996/7) 196 reports were received from 94 (22%) hospitals, but the reporting is now almost universal, with 99.5% registered to report, and 97.8% submitting greater than 3000 reports in 2012. Because the number of red cell units and components issued are known, it is possible to calculate risk estimates from the number of reports.
Local incident review
An important part of hemovigilance, or any scheme of adverse incident reporting, is the local review of the incident as well as the national reporting of serious events. The purpose of hemovigilance is to improve practice by understanding what went wrong and why. All organizations should be encouraged to develop reporting with a view to corrective and preventive actions and not to look for blame. The level of investigation will vary depending on the severity of the incident and the risk that it will recur.
Case study: a good root cause analysis
A 15-year-old boy regularly transfused for β-thalassemia major received a small amount of an incompatible red cell transfusion. His blood type was O and the transfused blood was group A. The transfusion was stopped and he suffered no adverse clinical consequences, although he was kept in hospital overnight for observation.
The root cause analysis demonstrated the following:
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The nurse was a lone worker and 3 children required transfusion; she therefore collected 3 units at one time because of staffing constraints despite that this was against hospital and national policy (which is to collect a single unit at a time).
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She borrowed a nurse from the next ward and checked each unit at the bedside with the correct patient, placing the units on tables between the beds.
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The first patient had a central line and required sterile access. The assisting nurse passed the unit to the first nurse; the unit was not checked again at the bedside as it was hung. The assisting nurse then returned to her own ward.
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The nurse realized the mistake as soon as she went to hang the blood unit for the next patient.
The case review established that this was a serious event that was likely to recur (scoring high on the risk matrix). Audit of practice demonstrated lone working on this ward occurred 74% of the time, and that transfusion observations were incomplete 47% of the time. The solution was to employ an additional nurse because it was clear that working alone had contributed to the potentially lethal error. The nurse involved needed revision of her competency assessment, but was supported for the manner in which she had dealt with the incident.
Hemovigilance contributes to a reduction in pathologic incidents
Annual reporting of incidents to SHOT has contributed to changes in practice at donor collection, resulting in fewer complications.
Reduction in Bacterial Infections
Bacterial infections from blood components are rare, but in the first 6 years of reporting 24 were described (6 fatal) with most contamination events caused by skin organisms contaminating platelet transfusions. SHOT and others recommended that strategies be developed to reduce this complication. Diversion of the first 20 mL of the donation was introduced in 2002, together with better techniques for skin cleansing, and bacterial screening of platelet concentrates in recent years. These better techniques resulted in fewer bacterial infections; there have been none since 2010.
Reduction in Cases of Transfusion-Related Acute Lung Injury
These cases were observed to be associated with plasma-containing components, particularly platelets, and most often from female donors. The reaction is usually related to antineutrophil antibodies in donor plasma. SHOT recommended in 2002 that female donors be excluded for production of fresh frozen plasma (FFP) and platelets, and this strategy, applied to plasma and as far as possible to platelets, has led to a reduced incidence of transfusion-related acute lung injury (TRALI) from a maximum of 36 cases with 7 deaths in 2003, to 11 with no deaths in 2012. Interestingly, the NBCUS for 2008 noted no difference in reports of TRALI despite the introduction of several TRALI reduction strategies (principally “to minimize the preparation of high plasma-volume components from donors known to be leukocyte-immunized or at increased risk of leukocyte immunization” and also to ensure that all transfusions are appropriate).
Observation of a reduction in events demonstrates the effectiveness of other strategies introduced by the blood services:
Transfusion-associated Graft Versus Host Disease
Universal leukodepletion was introduced in the United Kingdom in 1999. Following this, there have been no cases of transfusion-associated graft versus host disease since 2001 in patients who have received leukodepleted components, despite at least 800 recipients at risk receiving nonirradiated components, including children after hemopoietic stem cell transplants, those with immune deficiency, or those who had previously received intrauterine transfusion. The 2009 NBCUS reported that 80.4% of red cell units and 47.1% of platelets were leukodepleted in the United States in 2008 but leukocyte-reduced made up 68.6% of units transfused. Reports of posttransfusion purpura have also reduced since the introduction of leukodepletion.
Hemovigilance leads to recognition of particular at-risk groups
Patients Undergoing Hemopoietic Stem Cell Transplant
Individuals undergoing hemopoietic stem cell transplant may not receive appropriate components if the supplying transfusion laboratory is unaware that the transplant has taken place. Errors have been made with blood groups and failure to provide irradiated products. Good communication is the key to this.
Mistakes with Anti-D Administration to Pregnant Women
Failures may put women at risk of immune anti-D development with the possibility of hemolytic disease in future babies. Most errors are made by midwives.
Patients with Hemoglobinopathies
People with thalassemia major or sickle cell disease (SCD) have particular risks relating to both the disease and the fact that many have a different racial origin from the donor population, making it more likely that they will meet different red cell antigens.
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Patients with SCD were noted to be overrepresented among reports of hemolytic transfusion reactions. Many of these cases (69%) are associated with major morbidity and one child died. Alloimmunization is a well-recognized risk in SCD and particular care is needed in making the decision to transfuse, and the optimal choice of red cells. Patients should have their red cell phenotype analyzed preferably before any transfusion takes place, and the minimum recommendation is that red cells should be Rh and Kell matched. It is essential that the transfusion laboratory (Blood Bank) is aware of the diagnosis.
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Patients with thalassemia major are usually on regular transfusions. They continue to be at risk for acute transfusion reactions (ATRs; allergic type or febrile) and must be properly monitored with each transfusion.
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