Urticaria and Angioedema: Global Overview
To obtain a global overview on current practice in the management of urticaria and angioedema, a panel of international allergy experts was invited to complete an informal questionnaire on these allergic conditions. Responses were received from Australia, Brazil, Hungary, India, Israel, Italy, Japan, Russia, South Africa, Thailand and the USA. Estimates of the incidence of chronic urticaria ranged from 0.05%-2% of the population in the USA, to 20% in Thailand.
There was a wide variation in the laboratory studies considered for assessment of an otherwise healthy individual presenting with chronic urticaria and angioedema. These ranged from none, if there is no clinical indication for performing laboratory tests, to multiple tests which include: complete blood count, ESR, urinalysis and culture, total and specific IgE, antibodies to hepatitis A, B and C and mycoplasma, measurement of cryoglobulin and cryofibrinogen, immunoelectrophoresis, and cold agglutinins. C1 inhibitor, CH50, and complement components are checked for selected cases. Tests of thyroid function and thyroid antibodies are commonly recommended, particularly for female patients.
There is variation in the classification of physical urticarias. Some allergists classify physical urticarias as chronic urticaria; others classify physical urticarias as chronic when the symptoms persist for more than 8-12 weeks. Physical urticaria is also classified as a separate entity, subdivided into acute or chronic depending on the duration of symptoms.
There was consensus among the experts in regard to treatment regimes for chronic urticaria. The selection of H1 antihistamines for the treatment of chronic urticaria included cetirizine, which was specified by most respondents, with acrivastine, azelastine, ebastine, epinastine, fexofenadine, hydroxyzine HCl, loratadine and cyproheptadine being listed. Some specialists recommend a mix of different H1 antihistamines, whilst others combine H1 and H2 antagonists, for example, cetirizine with ranitidine. Cyclosporin is used in cases of auto-immune disease, with plaquenil, colchicine and dapsone variously considered if antihistamines are not effective.
For the treatment of urticaria in the absence of a satisfactory response to antihistamines, leukotriene antagonists are sometimes added, with montelukast and zafirlukast being suggested.
For the treatment of angioedema in the absence of urticaria and C1 inhibition, a regime of antihistamines and H1/H2 antagonists, with the addition of oral corticosteroids if required, was recommended by the majority of specialists.
C1 inhibitor and C4 levels should be determined for patients with angioedema in the absence of urticaria. When hives and swelling occur together, it is not necessary to check complement levels unless vasculitis is suspected, because patients with C1 inhibitor deficiency do not develop hives. A cold agglutinin titer or cryoglobulin level are indicated only when cold urticaria or its variants is a consideration.
Although controversial in terms of nosology, the inclusion of pure physical urticaria within the chronic urticaria spectrum is misleading (with the possible exception of delayed pressure urticaria) because the causes, pathogenesis and treatment parameters are completely different from that of chronic urticaria.
Low-dose alternate-day steroid treatment of severe chronic urticaria and angioedema should be considered where other modalities are ineffective. A typical dose is prednisone 20 mg every other day with a taper of 2.5 to 5.0 mg every 2-3 weeks depending on response. Glucocorticoid use for idiopathic angioedema involves a 1-3 day brief course and not sustained use.