Chronic urticaria – which clinical parameters are pathogenetically relevant? A retrospective investigation of 339 patients

Urticaria is a clinical reaction pattern triggered by many factors causing liberation of vasoactive substances such as histamine, prostaglandins and kinins. It presents as transient itching wheals which are either limited to the local stimulus area or more widespread. Urticaria is classified according to its duration into acute (duration > or = 6 weeks) and chronic (duration 6 weeks) forms. Various clinical investigations may be initiated to diagnose the cause. This study critically evaluates the relevance of frequently performed laboratory investigations and searches for infectious foci, as well as the results of physical provocation testing and oral provocation with food additives.The laboratory and clinical data of 339 patients who had been treated for urticaria at the Christian-Albrechts-University in Kiel over a period of four years were collected in a data entry form and statistically evaluated. Nominal values were analyzed by their relative and absolute quantities, quantitative parameters with the help of statistical data such as minimum, maximum, median and 25th and 75th percentiles.Chronic recurrent urticaria was most common, accounting for 52% of cases. Women were affected 1.8 times more often than men. One-third of the patients also had angioedema. The medians of all laboratory parameters evaluated were within normal values. Only rarely were elevated antinuclear antibody titers, abnormal thyroid function tests or active infections such as hepatitis B or borreliosis detected. The search for infectious foci identified tonsillitis or sinusitis in almost 50% of analyzed patients. Positive reactions to physical testing occurred in 30% of patients and in 11% to oral provocation with various food additives.This study of a large patient group stresses the relevance of individually-tailored evaluations in patients affected with urticaria rather than an expensive initial broad diagnostic testing. More specific searches should be based on individual clues.