Methodology development is essential for the TTA group to remain on the forefront of transfusion technology assessment research. Over the years a range of (published and unpublished) methodological innovations have been achieved, methods and tools developed and findings done. Among these are:
- A generic model (EUFRAT) for estimating the risk of infection transmission through the blood transfusion chain was developed and implemented in a web-based environment.
- A probabilistic model was developed to model the risk of transmission of infectious diseases through plasma derived medicines. This model showed that the risk estimates obtained by conventional calculation methods were similar to the probabilistic risk estimates but that this actually is a pure coincidence.
- A regression model was developed that allows estimating the effect of process conditions on virus reduction levels in viral safety studies using assay readings as observed outcomes.
- Statistical tests were developed to monitor tests for trends as well as exceedance risk levels in blood collection regions. It was concluded that the setting of the significance level of exceedance level tests only marginally affects the safety level of end products.
- Survival after transfusion (SAT) is an important variable to the QALY’s gained by blood safety interventions. TTA found marked differences between patient survival after the first transfusion versus the SAT for each individual component transfused. Evaluating methods for estimating SAT yielded that the Kaplan-Meier method may provide correct estimates but confidence intervals obtained by standard methods are incorrect.
- An adaptation of the nonparametric Mann-Kendall test for trend can lead to more meaningful outcomes as well as a higher power.
- Oei W, Janssen MP, van der Poel CL, van Steenbergen JE, Rehmet S, Kretzschmar ME. Modeling the transmission risk of emerging infectious diseases through blood transfusion. Transfusion 2012 Nov 1. [Epub ahead of print].
- Janssen MP, Over J, van der Poel CL, Cuijpers HTM, van Hout BA. A probabilistic model for analyzing viral risks of plasma-derived medicinal products. Transfusion 2008; 48(1):153-62.
- Van Geloven N, Cator EA, Lopuhaä HP, Janssen MP. Regression analysis on serial dilution data from virus validation robustness studies. Statistica Neerlandica 2009; 63(3):245-57.
- Janssen MP, Cator EA, van der Poel CL, Schaasberg WP, Bonsel GJ, van Hout BA. Monitoring viral incidence rates: tools for the implementation of European Union regulations. Vox Sang 2009; 96(4):298-308.
- Janssen MP; Modelling Blood Safety (PhD Thesis). ISBN 978-90-393-5401-8 (pdf). Utrecht, The Netherlands: 2010.