Introduction

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The current incidence of major complications due to blood transfusion is unknown. Until 1996 blood transfusion was not covered by either a confidential inquiry or the yellow card system of the Committee of Safety of Medicines. Perception of transfusion safety focuses on the diminishing risk of viral transmission, while the risk of ABO incompatible transfusion due to errors in blood or patient identification remains a threat. ^{1 2} To analyse the residual risks of transfusion, a confidential voluntary reporting system for major transfusion eventsserious hazards of transfusion (SHOT)affiliated to the Royal College of Pathologists was launched in 1996. We have summarised the main findings from its first two annual reports.

	Methods for case ascertainment

Top Abstract Introduction Methods for case ascertainment Results Discussion References

In November 1996 haematologists in the United Kingdom and Ireland were invited on a voluntary confidential basis to inform SHOT of deaths and major adverse events in seven categories (see results) associated with the transfusion of red cells, platelets, fresh frozen plasma, or cryoprecipitate. The SHOT launch was publicised at professional conferences and by an editorial in the BMJ.³ Suspected cases of post-transfusion infection were reported to local blood centres, and cases confirmed after donor investigation as related to transfusion were collated by the National Blood Authority/Public Health Laboratory Service Communicable Disease Surveillance Centre.

Incidents other than infections reported to the SHOT office were analysed with a questionnaire then entered on a secure database without identifiers. During the second year hospitals could submit a "nil to report" return card. We have analysed data relating to incidents that occurred between 1 October 1996 and 30 September 1998.

	Results

Top Abstract Introduction Methods for case ascertainment Results Discussion References

Overview
Of 424 eligible hospitals, 94 submitted 169 reports during the first year, with 112 hospitals submitting 197 reports during the second year, an increase of 16.5%. "Nil to report" cards, introduced in the second year, were submitted by 164 hospitals (39%), bringing overall participation to 65%. Reports included 191 incidents of incorrect blood transfused and 12 infections transmitted by transfusion (figure). Of 341 analysed cases, there were 22 deaths and 81 cases of major morbidity, with at least one death in every category (table).

View larger version (35K): [in this window] [in a new window]   Overview of 366 cases for which initial report forms were received

Incorrect blood or component transfused
Of the 191 reported episodes in which a patient was transfused with a wrong blood component, 62 were ABO incompatible transfusions, leading to three deaths, 25 cases requiring intensive care, and six cases of potential rhesus D sensitisation in young female patients. The errors in 177 analysed cases of incorrect transfusion generally consisted of a sequence of one to seven failures to detect incorrect identity of blood or patient, leading to transfusion to the wrong patient (one error103 cases; two errors40 cases; three errors26 cases; four errors2 cases; six errors5 cases; seven errors1 case). First errors occurred at all stages of the process: during the request for blood or sampling of the patient, or both (33), including two incidents (one fatal) of transposition of blood grouping samples at the patient's bedside, and in the transfusion laboratory (59). Collection of the wrong blood from the blood bank refrigerator was the major source of primary error (61), with blood frequently taken without a formal identity check against the patient's case record. The bedside check failed to detect discrepancy in blood or patient identity in a total of 80 cases, despite being carried out by two people (one always a qualified nurse or doctor). In 20 incidents, the patient had no identity wrist band.

Immunological interactions between donor and patient
Immunological interactions were reported in five categories (acute and delayed reactions, post-transfusion purpura, transfusion associated graft versus host disease, and transfusion related acute lung injury). These cases were unpredictable and generally did not represent poor practice. In two cases, however, haemolytic antibodies were missed because of non-compliance with current guidelines.⁴ Occasionally, relevant information was not available because the blood bank computer could not be accessed.

Transfusion transmitted infection
Twelve of 60 suspected cases (20%) were confirmed to be related to the transfusion. Six cases (one hepatitis A infection, one malaria, four bacteraemias) were due to infections for which no testing of donations is performed, while five cases (three hepatitis B, one hepatitis C, one HIV) were due to donations from repeat donors during marker negative "window periods" after recent infection. A further newly reported case of infection with hepatitis C virus was in a patient who received a transfusion before the introduction of donor screening in 1991. The HIV transmission involved components from one donor transfused to three different recipients. The three non-fatal bacterial incidents involved red cells contaminated with Serratia liquefaciens, platelets containing Escherichia coli, and leucocyte depleted platelets containing Bacillus cereus, also grown from the donor's arm. Fatal septicaemia due to Staphylococcus aureus occurred in one platelet recipient. S aureus was also isolated from the donor's skin and nose.

Key recommendations and feedback
Major findings and the recommendations arising from them are summarised in the box. Detailed annual reports were sent to all haematologists, ^{6 7} with a summary to trusts' chief executives and blood bank managers. Seventy nine hospitals had already reviewed procedures for blood handling and staff training after the incident reported. The SHOT findings were highlighted at a transfusion seminar organised by the United Kingdom chief medical officers, and participation in SHOT was recommended in a health service circular to trusts.⁸

	Discussion

Top Abstract Introduction Methods for case ascertainment Results Discussion References

Voluntary reporting of serious complications of transfusion has its limitationswe may be seeing only the tip of the iceberg, viral infections may present years after acquisition, and there are no denominators from which to calculate hazard incidence. The incidence of ABO incompatible transfusions reported here (62 in 2 years), however, is not significantly different from that seen in the French haemovigilance system (58 in 3 years), to which reporting is mandatory.⁹ In the second year, SHOT implemented a nil to report card; this revealed that the 65% of participating hospitals handled 70% of all red cells issued in the United Kingdom. SHOT findings therefore do seem representative of transfusion practice.

The two annual reports have provided the first detailed analysis of transfusion errors in the United Kingdom, an approach already recommended in the United States.¹⁰ Following defined procedures for blood handling¹¹ and regular staff training are crucial; bedside ABO grouping has a high error rate¹² and is not recommended by SHOT, although it is mandated in France. Medical and nursing staff must be aware of the possibility of ABO incompatibility or bacterial infection in a shocked recipient of transfusion, while errors in identification will be minimised by procedural training for porters and phlebotomists and by forthcoming guidelines for blood handling and administration from the British Committee for Standards in Haematology. Infections transmitted by transfusion were relatively rare, a finding consistent with the calculated low residual viral risk,¹³ now overtaken by the frequency of bacterial contamination of platelet concentrates.¹⁴ SHOT data provide mixed messages: the risk:benefit ratio of appropriate transfusion is high compared with other risks in life,¹⁵ but safety can still be improved. The United Kingdom lacks a unified body to take an overview of all aspects of blood safety, sometimes making it difficult to practise "aligning effort with risks."¹⁶ Technological advances such as viral genomic detection and inactivation may be mandated by regulatory authorities, but prevention of transfusion error requires local managerial commitment, "process re-engineering,"¹⁷ and an active hospital transfusion committee. Hopefully the concept of clinical governance will focus resources in this important area.

	Acknowledgments

   Contributors: LMW, EML, PS, and JAJB took part in the establishment of the SHOT scheme, design of the questionnaire, analysis of data, and compilation of the report. SL, HC, and KS took part in design of the questionnaire, analysis of data, and compilation of the report. DBLMcC took part in the establishment of the SHOT scheme, analysis of data, and compilation of the report. LMW, HC, and EML are the guarantors.

	Footnotes

Funding: UK Transfusion Services, Republic of Ireland Transfusion Service, British Society for Haematology, British Transfusion Society.

Competing interests: None declared.

	References

Top Abstract Introduction Methods for case ascertainment Results Discussion References

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(Accepted 19 April 1999)