Foodborne illness, hygiene scores, and the “switch effect”

Abstract

This paper demonstrates the health and economic impact of mandated posting of food hygiene rating scores at the point of purchase. By developing a mathematical model to compare Wales and Northern Ireland, where posting stickers showing hygiene scores is mandatory, to England, where posting is optional, we created a method to predict the health and economic impact of mandated posting. To estimate the reduction in cases of foodborne illness in England and the resultant cost savings if posting stickers were mandatory in England as in Wales and Northern Ireland, we developed a mathematical model using information from several sources including data showing the connection between hygiene scores and microbiological contamination, data from a consumer survey, audited and compared display rates, and estimates of foodborne disease rates. Developing a new concept, the “switch effect,” we determined how many consumers in England would preferentially choose a higher-scoring premises if hygiene scores were posted. Based on evidence that many consumers in England would switch to better scoring facilities, we conclude there would be a reduction in foodborne illness of 3700 cases (95 % credible intervals 1000 to 8500) annually and a reduction in economic burden of 15.7 million per year (95 % credible intervals £4.3 million to £35.8 million), providing support for mandatory posting requirements.