Physical urticaria: prevalence, type and natural course in a tropical country

Physical urticarias (PU) are an urticarial response to different specific physical stimuli. PU can occur concurrently with chronic spontaneous urticaria or another type of PU.

We aimed to study the prevalence, type, clinical data and natural course of each type of PU and other inducible urticarias and also the prognostic factors for remission of patients visiting a tertiary referral hospital.

We performed a retrospective study of 1200 chronic urticaria patients who visited our Urticaria Clinic during a period of 5 years.

Of the 1200 chronic urticaria patients, 86 (7.2%) were diagnosed as PU and other inducible urticarias. The most common type of PU was symptomatic dermographism (n = 35, 40.7%) followed by cold urticaria (n = 20, 23.3%) and delayed pressure urticaria (n = 11, 12.8%), respectively. Twelve patients (13.9%) had associated chronic spontaneous urticaria. None of the cases had multiple types of PU. Erythrocyte sedimentary rate elevation was the most common abnormal laboratory result. Nevertheless, only 4.6% declared a related infection. For each type, the median time after onset before 50% remission showed that cholinergic urticaria took the shortest course (34 months) and delayed pressure urticaria took the longest period (110 months). After 1 year and 5 years from the onset of symptoms, 13% and 50% of PU patients were free of symptoms, respectively.

This study emphasized the variety of PU, other inducible urticarias and natural courses based on tertiary hospital care. PU and other inducible urticarias have tendency to have a longer course than chronic spontaneous urticaria.