The Incidence and Other Aspects of Factitious Wealing (Dermographism)

Summary.— Using an instrument designed to exert known pressures on the skin, an incidence survey of factitious wealing in the general population has been carried out; 2813 subjects have been tested with a pressure of 4900 g/cm2, and the overall incidence was 4·24% (females, 5·2%; males, 4·34%). The incidence did not vary significantly in the different age groups. A series of patients with symptomatic dermographism has been followed up in the outpatient Department and serial measurements of the weal size have been made. In 20 of these comparable measurements are available over prolonged periods. The total number of patients showing at least 50% reduction in weal size was: at 2 months, 1; at 4–6 months, 7; at 6–9 months, 10; at 9–12 months, 12. The incidence of factitious wealing in various patterns of urticaria is mentioned and the results of the incidence survey are discussed in relation to patients presenting with symptomatic dermographism.