P0483 SKIN PRICK TESTS AND RASTS IN THE DIAGNOSIS OF COW MILK ALLERGY WITH EXCLUSIVE GASTROINTESTINAL SYMPTOMS

Abstract

Introduction: The provocative challenge test is still considered gold standard in the diagnosis of food hypersensitivity. However this test requires many cautions and can espose the patients (pts) to sometimes severe allergic symptoms. Therefore the diagnostic approach to food hypersensitivity could be made safe and fast by laboratory tests gifted of good predictive value in comparison with the gold standard. Aim of this retrospective study was to evaluate predictive value of skin prick tests (SPTs) and RASTs in comparison with the open challenge in the diagnosis of cow milk allergy with exclusive gastrointestinal symptoms. Methods: Ninety-six consecutive patients (pts), 41 females and 55 males, mean age 7.2 ± 2.6 years were enrolled. Inclusive criteria was: exclusive gastrointestinal symptoms (vomiting, diarrhea and abdominal pain); medical history suggestive of cow milk hypersensitivity and age more than 4 years. SPTs and RASTs for the main cow milk protein (casein, β-lactoglobulin and lattoalbumin) were performed in all pts; these pts affected by diarrhea and abdominal pain also underwent lactose breath test. All pts started a cow milk free diet and after 20 days from the beginning of the elimination diet underwent an open challenge test. A provocative test with lactose free milk was performed in all pts positive to lactose breath test. According to open challenge the pts were divided in two groups: group A (pts with positive open challenge) and group B (pts with negative open challenge). Results: GroupA (79 pts): 19 % were positive and 71 % negative to SPTs; 70% positive and 30% negative to RASTs; 4% were positive to SPTs and negative to RASTs; 58% were negative to SPTs and positive to RASTs. The number of the positive RASTs pts was significantly higher (p 0.00001) than of the positive SPTs pts. The 10 % resulted positive to lactose breath test. Group B: 6% were positive and 94 % negative to SPTs and to RASTs; 6% were positive to SPTs and negative to RASTs; 6% were negative to SPTs and positive to RASTs. The 53 % were positive to lactose breath test. Therefore the SPTs and RSTs sensitivity and specificity reached respectively 21%, 73%, 94% and 94%; the SPTs and RSTs positive and negative predictive values were respectively 28%, 57%, 91% and 97%. Conclusion: Our study shows that the RASTs are more reliable than the SPTs in the diagnosis of cow milk allergy with exclusive gastrointestinal symptoms and suggestive medical history.