Multiple NSAID intolerance in chronic idiopathic urticaria is correlated with delayed, pronounced and prolonged autoreactivity.

Autologous serum skin test (ASST) reactivity is positive in up to 60% of patients with chronic idiopathic urticaria (CIU). About 21 to 30% of patients with CIU have intolerance to acetyl salicylic acid (ASA) and/or other chemically unrelated non-steroidal anti-inflammatory drugs (NSAIDs). To investigate the relationship between ASA/NSAID intolerance and ASST reactivity, a case-control study was performed in 110 patients with CIU and 60 healthy controls. A positive ASST was defined as an erythematous wheal with a diameter of > 5 mm more than the saline-induced response. Patients were assessed at 10-minute intervals for a minimum of three hours. ASA/NSAID intolerance was ascertained by a placebo controlled-provocation test with offending drug (s). Forty-two patients with CIU (38.2%) had autoreactivity whereas only two of the controls (3.3%) displayed early and weak skin responses (P<.0001). ASA/NSAID intolerance was demonstrated in 30 (27.3%) patients with CIU. The prevalences of autoreactivity were 93.3% (28/30) and 17.5% (14/80) in patients with and without ASA/NSAID intolerance, respectively (P<.001). Thirteen of the 25 ASST-positive patients (52%) who had single (n: 7) or multiple (n: 6) NSAID intolerance showed early (before or at 30 min) and mild autoreactivity of short duration, whereas 15 of the remaining 17 ASST-positive patients (88.2%) who all had multiple NSAID intolerance showed delayed (later than 30 min) and prolonged autoreactivity (P<.05). These findings suggest that a common mechanism may be responsible for the pathogeneses of both delayed autoreactivity and multiple NSAID intolerance in CIU. It might be further speculated that delayed, prolonged, and pronounced autoreactivity may be a possible predictor for multiple NSAID sensitivity in CIU.