ORIGINAL PAPER Incremental build-up food challenge – a new diagnostic approach to evaluate pseudoallergic reactions in chronic urticaria: a pilot study Stepwise food challenge in chronic urticaria B. Bunselmeyer à , H. J. Laubach à , M. Schiller à , M. Stanke w , T. A. Luger à and R. Brehler à à Department of Dermatology, University Hospital M ¨ unster, M ¨ unster, Germany and w Department of Bioinformatics, Georg-August-University, G ¨ ottingen, Germany Clinical and Experimental Allergy Correspondence: Britta Bunselmeyer, Department of Dermatology, University Clinics M¨ unster, Von-Esmarch-Str. 58, 48149 M¨ unster, Germany. E-mail: Britta.Bunselmeyer@ukmuenster.de Cite this as: B. Bunselmeyer, H. J. Laubach, M. Schiller, M. Stanke, T. A. Luger and R. Brehler, Clinical and Experimental Allergy, 2009 (39) 116–126. Summary Background The remission rate of patients with chronic urticaria (CU) due to elimination diets varies between 31% and 71%. However, the diagnostic value of subsequent traditional oral provocation tests with food additives in capsules remains unsatisfactory. Objectives A newly incremental build-up food challenge (IBUF) for patients with CU was designed and implemented in an open pilot study. Primary endpoint was the percentage of patients developing urticaria during at least one step of IBUF after an initial complete remission due to a pseudoallergen-free elimination diet. Methods In total, 153 patients with CU were submitted for 5 weeks to a pseudoallergen-free diet. All patients with remission were included to the 6-week IBUF protocol, containing pseudoallergen-rich foods in a systematic and additive manner. The recurrence and severity of CU was evaluated by urticaria score. Subjective disturbance and quality of life were evaluated by patients’ diary, visual analogue scale and quality of life questionnaire (CU-Q 2 oL). Subsequently, patients were followed up for 3–24 months after IBUF by a telephone interview. Results A total of 104 patients completed the pseudoallergen-free diet, whereby 51% reported partial, 17% complete and 32% no remission due to the diet. All diet responders showed a decrease in subjective impairment, urticaria and quality of life score (Po0.001 each). Eighty- six percent (12/14) of the patients reaching complete remission, showed a recurrence of urticaria symptoms during the IBUF protocol. Fifty-eight percent (7/12) of these patients still remained free of symptoms due to avoidance of IBUF-identified foods at telephone follow-up. In patients with partial remission to pseudoallergen-free diet, however, IBUF did not provide information about the cause of urticaria symptoms. Conclusions The newly developed IBUF protocol seemed to be a promising method for identifying individually incompatible foods in some CU patients. IBUF should be verified by randomized controlled trials to gain additional evidence for its diagnostic value. Keywords additives, chronic urticaria, diet, elimination diet, food challenge, IBUF, oral provocation diet, outpatient, pseudoallergens, pseudoallergic Submitted 30 April 2008; revised 6 July 2008; accepted 19 August 2008 Introduction Chronic urticaria (CU) is affecting 0.1–3% of the popula- tion in the USA and Europe. The classification is based on duration, frequency and causes. CU can be related to infectious or inflammatory processes, but is diagnosed as idiopathic in approximately 75% of the cases [1–3]. Here- unto include urticaria due to pseudoallergic reactions to food ingredients. Remission rates due to elimination diets are reported in the range between 31% and 100%, comprising ‘full’ and ‘partial’ responders [4–17]. Only few publications exist with a clear differentiation between full and partial response. In many studies, diet responders are determined by a reduction in symptoms and/or medication intake and are not distinguished from full responders (non-existent of symptoms and no medication intake). A ‘full’ response after different dietary elimination interventions is Clinical Allergy doi: 10.1111/j.1365-2222.2008.03110.x Clinical and Experimental Allergy, 39, 116–126  c 2008 The Authors Journal compilation  c 2008 Blackwell Publishing Ltd