Transfusion Transmitted Injuries Surveillance System Program Report 2004-2005

Executive Summary

The Transfusion Transmitted Injuries Surveillance System (TTISS) evolved from a pilot project in 1999-2002 involving four provinces (British Columbia, Québec, Prince Edward Island, Nova Scotia) and has become the national surveillance system for capturing serious, moderate and selected minor adverse transfusion events reported in Canada. Adverse transfusion events that are captured through TTISS are compiled, analyzed and reported by the Public Health Agency of Canada (PHAC). In 2004-2005, nine Provinces and two Territories participated in the TTISS, which has expanded from 56 reporting hospitals in 2002 to 291 hospitals during 2004-2005. The hospitals reporting at the end of 2005 represented 70% of red blood cell transfusions occurring in Canada.

TTISS has continued to apply strict criteria for accepting cases and, overall, the quality of data has improved over previous years. The TTISS in its first two years had 244 adverse transfusion events reported compared to 569 in 2005 alone. In 2005, the top three reported adverse transfusion events were TACO, severe allergic (also called severe/anaphylactic/anaphylactoid) and TRALI.

The severity of reported cases in 2004-2005 has decreased compared to the period 2002-2003, which may be explained by a change in the reporting criteria for some adverse transfusion reactions. For example, in 2004-2005, all cases of TACO and delayed hemolytic transfusion reaction were to be reported while only the most severe cases of these two types of reactions were reportable in 2002-2003. There were 13 deaths possibly, probably or definitely related to transfusion, which represents 1.4% of all reported adverse transfusion reactions included in the analysis for the 2004-2005 period. Transfusion was only one of the contributing factors of death in more than half of these cases of adverse transfusion events; death was definitely related to transfusion in only 4 cases.

The incidence of bacterial contaminations has continued to decline and was ten-fold less in 2005 compared to 2002 (0.3 vs. 3.7 per 100,000 units, respectively). Implementation of diversion pouches at blood collection and tests for bacterial detection of platelets has likely contributed to the observed trend. There was also a two-fold decrease in the incidence of ABO incompatible transfusions between 2002 and 2005 (1.5 vs. 0.7 per 100,000 units).

In 2004-2005, TRALI occurred at a rate of approximately 2.5 per 100,000 blood units transfused. The reduction in the incidence of TRALI compared to 2002-2003 is likely explained by the use of a new and more restrictive definition of TRALI for inclusion of reported cases. The incidence of TRALI for the 2004-2005 period is probably an underestimation because many cases were reported to Canadian Blood Services by hospitals that were not participating in TTISS and were therefore not included in the calculation of incidence rates.

TACO occurred at a rate of 11.9 per 100,000 blood units transfused in 2004 and 13.5 per 100,000 units in 2005. The rise in incidence of TACO since 2002-2003 can be partly attributed to new reporting criteria for this reaction.

Severe allergic reaction occurred at a rate of 4.5 per 100,000 blood units transfused in 2004 and 5.5 per 100,000 units in 2005. This represented a two-fold decrease in incidence compared to the 2002-2003 period.

Future initiatives in the surveillance of adverse transfusion events include upgrading the TTISS database to a web-based system, which will also incorporate a module for reporting of transfusion-related errors. Also, PHAC, in collaboration with stakeholders, has developed guidelines for investigating bacterial contamination that were published in early 2008.