Anaphylaxis in adults referred to a clinical immunology/allergy centre in Singapore

BYH Thong, YK Cheng, KP Leong, CY Tang, HH Chng
Correspondence: Dr Bernard Thong Yu Hor, bernard_thong@ttsh.com.sg

ABSTRACT
Introduction To study the clinical features and causes of anaphylaxis in consecutive adult patients referred to a clinical immunology/allergy centre in Singapore.
Methods A retrospective review of 67 consecutive adults with anaphylaxis who presented from July 1, 1998 to February 28, 2002 was performed. Anaphylaxis was defined as a severe life-threatening systemic IgE-mediated hypersensitivity reaction. Non-steroidal anti-inflammatory drug-induced idiosyncratic reactions and other non-IgE mediated reactions were excluded. Hypotension and bronchospasm were not required to make a diagnosis. The aetiology was determined from clinical history followed by measurement of allergen-specific IgE levels, skin prick test with commercially-available allergen extracts or prick-prick test with the fresh/cooked/canned food products.
Results The mean age of patients was 32.9 +/- 10.9 (range 19-57) years. There were 44 (65.7 percent) males and 23 (34.3 percent) females. The main causes were food (44.8 percent), insect stings (32.8 percent) and idiopathic (22.4 percent). There were no cases due to drugs or natural rubber latex. Seafood (crustaceans and molluscs) comprised 66.7 percent of food-induced anaphylaxis. Honeybee and wasp stings together comprised 45 percent of insect venom anaphylaxis. The most common manifestations were dyspnoea (59.7 percent), urticaria (58.2 percent), angioedema (44.8 percent), and syncope (43.3 percent). Hypotension was documented in only 28.4 percent of cases.
Conclusion Food (crustaceans and molluscs) was the most common cause followed by insect stings or bites. The inability to identify the causative insect in 50 percent of cases with insect venom anaphylaxis limited the role of specific immunotherapy. Compared to other reported series, there were no cases of drug or latex anaphylaxis.

Keywords: hypersensitivity, radioallergosorbent test, skin tests, immunotherapy
Singapore Med J 2005; 46(10): 529-534