Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention
A modeling framework for evaluation and comparison of trigger strategies for switching from minipool to individual-donation testing for West Nile virus
Version of Record online: 27 FEB 2009
© 2009 American Association of Blood Banks
Volume 49, Issue 6, pages 1151–1159, June 2009
How to Cite
Biggerstaff, B. J. and Petersen, L. R. (2009), A modeling framework for evaluation and comparison of trigger strategies for switching from minipool to individual-donation testing for West Nile virus. Transfusion, 49: 1151–1159. doi: 10.1111/j.1537-2995.2009.02112.x
- Issue online: 1 JUN 2009
- Version of Record online: 27 FEB 2009
- Received for publication September 4, 2008; revision received December 19, 2008, and accepted December 22, 2008.
BACKGROUND: To decrease the likelihood of transmission from donations containing West Nile virus (WNV) levels below minipool nucleic acid test (MP-NAT) detection limits, blood centers switch from MP-NAT to individual-donation testing (ID-NAT) after detection of MP-NAT–positive donations. The effectiveness of strategies to trigger or discontinue ID-NAT screening is largely unknown.
STUDY DESIGN AND METHODS: Twenty-seven strategies to trigger and discontinue ID-NAT screening were evaluated with a statistical model based on known dynamics of WNV infection and historical data on WNV prevalence among blood donations. Breakthroughs were defined as WNV immunoglobulin M antibody–negative, viremic (RNA-positive) donations that could only be identified by ID-NAT, but were screened by MP-NAT. Effectiveness (proportional reduction of breakthroughs relative to MP-NAT screening alone) and efficiency (absolute reduction of breakthroughs relative to the number of tests performed) were estimated by simulating donation years of varying outbreak severities over a range of blood collection frequencies.
RESULTS: Most strategies were effective (>75% reduction in breakthroughs) when daily donations exceeded 560. In larger centers (1008 donations daily), effectiveness of trigger-on strategies based on absolute number of MP-NAT–positive donations improved, but worsened for strategies using rate-based criteria. Effectiveness increased slightly by triggering on one MP-NAT–positive rather than two and increased substantially by increasing the duration from 7 to 14 days that no ID-NAT–positive donations are detected before resuming MP-NAT.
CONCLUSION: Most trigger strategies become effective when test results from at least 560 donations daily are considered. A 14-day ID-NAT period may improve safety relative to the increase in the number of tests performed.