Are double-blind food challenges necessary before starting an elimination diet?
Food allergy is normally treated by eliminating the offending food. Such a measure, however, may cause nutritional and sociopsychological problems, so an allergy must be diagnosed with the utmost certainty. To date the most reliable diagnostic test is the double-blind food challenge (DBFC). The rationale for using this test is the marked difference in positive results with open and double-blind food challenges. Only about 30% of open challenges that appear positive are confirmed on blind challenge. There is ample evidence, too, that a negative DBFC may in fact indicate tolerance to that food. From the literature it appears that almost all patients who reintroduced a certain food into their diet after a DBFC had given negative findings did not present any adverse reaction to it. In our caselist of 21 patients with probable reactions to foods but negative DBFC, 19 (90.5%) tolerated the "incriminated" food well when it was reintroduced into their diet even in unlimited amounts. Only two (9.5%) again presented symptoms when they started taking large amounts of the problem food. Therefore, one precaution recommended before reintroducing a food item into a patient's diet after a negative DBFC is to check how it is tolerated at high doses. A review of the literature confirms the unquestioned utility of the DBFC. Nevertheless, in some situations this test is not indicated. The main one, of course, is in patients with life-threatening symptoms such as anaphylactic shock or glottis edema, in whom any provocation test is contraindicated.(ABSTRACT TRUNCATED AT 250 WORDS)
Pastorello
E A
EA
Department of Internal Medicine, University of Milan, School of Medicine, Italy.
Pravettoni
V
V
Stocchi
L
L
Bigi
A
A
Schilke
M L
ML
Zanussi
C
C
D004032:Diet; D004311:Double-Blind Method; D005512:Food Hypersensitivity / Q000175:diagnosis* / Q000523:psychology / Q000628:therapy; D006801:Humans; D008722:Methods