In Europe the regulation on in vitro diagnostics (
IVDR) defines companion diagnostics as
devices that are essential for the safe and effective use of corresponding medicinal products to identify, before and/or during treatment, patients who are most likely to benefit from the corresponding medicinal product; or to identify, before and/or during treatment, patients likely to be at increased risk of serious adverse reactions as a result of treatment with the corresponding medicinal products. ==See also==