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Diagnostic Utility of Challenge Procedures for Physical Urticaria/Angioedema Syndromes: A Systematic Review.
Monday, March 7, 2016
South Exhibit Hall H (Convention Center)
Lyda Cuervo Pardo, MD, Alexei Gonzalez-Estrada, MD, David M. Lang, MD FAAAAI
Rationale: Physical urticaria/angioedema syndromes (PUAs) are commonly encountered.  PUAs are identified by a history of physical triggers provoking symptoms, and diagnosed by provocation testing; however, positive/negative likelihood ratios (LR) have not been established for challenge procedures recommended in recent guidelines (J Allergy Clin Immunol 2014;133:127).  We conducted a systematic review to determine the diagnostic utility of practical office procedures recommended for three common PUAs: dermatographia (DERMATO), cholinergic urticaria (CU), and delayed pressure urticaria/angioedema (DPUA).

Methods: Literature searches were conducted up to May 13, 2015, on EMBASE, MEDLINE, PubMed and SCOPUS databases. We included studies for PUAs with diagnostic challenge testing compared to a reference standard (Ann Intern Med 1994;120:667-676). Two authors independently appraised study quality, extracted and analyzed data.

Results: A total of 2505 citations were identified, of which 1875 were not relevant. None of the 108 studies of DPUA or 307 of DERMATO satisfied our inclusion criteria. Of 215 studies of CU, 4 of small size, with 33 CU patients, were accepted as fulfilling criteria. Patient data were combined: methacholine intradermal challenge compared to exercise challenge (reference standard) was associated with a sensitivity= 24.2%. Data were not sufficient to calculate specificity or positive/negative LR. 

Conclusions: We were unable to identify studies of sufficient methodologic quality to calculate positive/ negative LR to recommend diagnostic challenges for PUAs.  Limited data imply that methacholine intradermal challenge is associated with a low sensitivity for CU. There is a need for well-designed studies to aid the clinician in interpretation of diagnostic challenges for patients with DERMATO, CU, and DPUA.