Volume 114, Issue 2 pp. 107-116
Original Paper

Modelling the risk of transfusion-transmitted syphilis: a reconsideration of blood donation testing strategies

Thisuri Jayawardena

Thisuri Jayawardena

Faculty of Health and Medical Sciences, University of Western Australia, Perth, WA, Australia

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Veronica Hoad

Corresponding Author

Veronica Hoad

Australian Red Cross Blood Service, Perth, WA, Australia

Correspondence: Veronica Hoad, Australian Red Cross Blood Service, 290 Wellington St, Perth WA 6000, Australia

E-mail: [email protected]

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Claire Styles

Claire Styles

Australian Red Cross Blood Service, Perth, WA, Australia

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Clive Seed

Clive Seed

Australian Red Cross Blood Service, Perth, WA, Australia

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Peter Bentley

Peter Bentley

Faculty of Health and Medical Sciences, University of Western Australia, Perth, WA, Australia

Australian Red Cross Blood Service, Perth, WA, Australia

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Vanessa Clifford

Vanessa Clifford

Australian Red Cross Blood Service, Melbourne, VIC, Australia

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Sarina Lacey

Sarina Lacey

Centre for International Economics, Sydney, NSW, Australia

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Tessa Gastrell

Tessa Gastrell

Centre for International Economics, Sydney, NSW, Australia

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First published: 18 December 2018
Citations: 16

Abstract

Background and Objectives

Donor syphilis testing began in the 1940s amidst widespread transfusion-transmitted syphilis (TTS). Since then, the introduction of penicillin, pre-donation screening questionnaires and improved storage conditions have contributed to reducing transmission risk. Consequently, universal testing may no longer be cost-effective. This study analysed alternative options for donor syphilis testing to determine the optimal strategy.

Materials and Methods

A model was developed using conservative parameter estimates for factors affecting TTS and 2009-2015 Australian donations to calculate risk outcomes (TTS infections, tertiary syphilis in recipients and transfusion-associated congenital syphilis) and cost-effectiveness of alternative testing strategies. The strategies modelled were as follows: universal testing, targeted-testing of high-risk groups (males ≤50 years old and first-time donors) and no testing.

Results

The estimated risk of TTS is one in 49·5 million transfusions for universal testing, one in 6 million for targeted-testing of males ≤50 years old, one in 4 million for targeted-testing of first-time donors and one in 2·8 million for no testing. For all strategies, the risk of tertiary and congenital syphilis is <1 in 100 million. Universal testing is the least cost-effective strategy with an incremental cost-effectiveness ratio (ICER) estimated at $538·5 million per disability-adjusted life year averted.

Conclusion

Universal testing is not required to maintain the risk of TTS within tolerable limits and is estimated to greatly exceed acceptable ICERs for blood safety interventions. However, despite a strong economic and risk-based rationale, given the epidemiology of syphilis in Australia is changing, feedback from critical stakeholders is not currently supportive of reducing testing.

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