With any restaurant inspection disclosure system, one of the overriding objectives is a measurable reduction in foodborne illnesses. The question is: does putting an A on the front of a restaurant mean fewer people barf?

WNYC reports this morning that a 2003 study by two economists found that after letter grades were introduced in Los Angeles, there was a 20 per cent decline in hospital admissions for foodborne illness.

In the world of public health, that was a dramatic result. Yet this study is the only academic work to date that shows a connection between restaurant letter grades and rates of foodborne illness.

There’s a reason there’s only been one such paper: causation is not the same as correlation.

Katie Filion (left, pretty much as shown) gave a departmental seminar this morning – we’re both in diagnostic medicine and pathobiology in the veterinary college at Kansas State University — critiquing the paper and presenting some results from her year in New Zealand developing a national restaurant inspection disclosure system.

Filion said there was no accounting for different sources of, say, salmonella (pets cause it too), no accounting for whether food was contaminated at home, in the field or in a restaurant, and no accounting for statistical validity. There may have been a reduction of hospital admissions once inspection scores were posted, but that could have been due to increased awareness, a correlation of interest, but not causation.

A philosophy of transparency and openness underlies the efforts of many local health units across North America in seeking to make available the results of restaurant inspections. Such public displays of information may help bolster overall awareness of food safety amongst staff and the public — people routinely talk about this stuff. It’s all about that food safety culture.

The New Zealand stuff? Katie can talk about that after she defends her thesis.