Methodological issues in the diagnostic work-up of food allergy: a real challenge.

The standard of reporting in diagnostic studies has generally been low. Fortunately, this issue has begun to be addressed in recent years through the discussion of important methodological issues in educational series, textbooks, and checklists. Double-blind, placebo-controlled, oral food challenges (DBPCFC) are considered to be the gold standard for diagnosis of food allergy. However, there is no consensus regarding how to interpret the outcome and how to define positive and negative provocations in DBPCFC. Furthermore, since most theories on the diagnosis of food allergy rely on the assumption that the DBPCFC has a high accuracy, this accuracy must be formally statistically evaluated. In this review, we discuss essential methodological issues for diagnostic accuracy studies in general and for oral food challenges in particular and discuss the importance of methodological issues as a guide for forthcoming studies of diagnostic procedures.