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Importance of Patch Test in Diagnosing Chronic Spontaneous Urticaria
Monday, March 7, 2016
South Exhibit Hall H (Convention Center)
Maged Refaat, MD, Rasha Shahin, MD, Asmaa Moustafa, MD, Walaa Abu El-Yazeed, MB,BCh
Rationale: Chronic spontaneous urticaria (CSU) is defined as the occurrence of almost daily wheals and itching for at least 6 weeks, with no obvious cause. Specific laboratory tests should be carried out to discover the suspected cause .Our aim was to investigate the possible significance of patch test (PT) which depends on type IV and delayed type I hypersensitivity with common allergens in diagnosis of CSU

Methods: Fifty patients having CSU were selected from Allergy and Clinical Immunology outpatient clinic of Ain Shams University Hospitals, with 50 healthy controls. Blood and immunological tests were done to exclude known causes of chronic urticaria. (PT) was done using common aeroallergens, food, chemicals, metals and drug allergens

Results: The patch test results were positive in 22(44.0%) of case group with 3(6%) positivity among the control group. The sensitivity to the PT was 44%, the specificity was 94%, the positive predictive value was 88% and the negative predictive value was 63%. Most of patients showed positivity to mixed group of allergens.PT was positive in 42.9% to food allergens, 18.4% to drugs, 26.5% to chemicals and 24.5% to aeroallergens

Conclusions: Patch test showed satisfactory results to be used in diagnosing chronic spontaneous urticaria as it show high specificity and predictive values in comparison to control