Erythema, localized edema and heat vs forearm perimeter increase. Time to revise the consensus recommendations on the vortex provocation test in vibratory urticaria-angioedema?

Background and objective: Diagnosis of vibratory urticaria/angioedema is established after performing the vortex provocation test. There is current consensus on measuring the forearm perimeter after running such test to define a positive response to it.

Material and method: We evaluated the frequency of prior symptoms following vibratory stimuli in volunteers using a questionnaire, response to the vortex provocation test in the same volunteers (increase in forearm perimeter, erythema, localized edema, heat, and pruritus), interrater reliability, and correlation between the scores obtained in the questionnaire and response to the test.

Results: A total of 40 volunteers participated in this survey, 17 of whom were excluded due to dermographism. A total of 59% out of 123 without dermographism responded positively to ≥ 1 items of the questionnaire. Localized erythema, heat or localized edema were reported in 58.5%, 38.2%, and 32.5%, respectively. A total of 73.6% of volunteers presented with itch. The mean intensity of itch was 3.44 (95%CI, 2.94-3.94). Interrater agreement was low regarding the increase in forearm circumference at 3 levels (intraclass correlation coefficient, 0.477 95%CI, 0.253-0.634; 0.496 95%CI, 0.280-0.647; and 0.370 95%CI, 0.100-0.559, respectively) and optimal regarding erythema, heat and localized edema (Kappa index, 0.868; .756; and .757, respectively). A significant correlation was identified between the questionnaire score and the altered response to the test in its different variables.

Conclusions: We propose the following variables: erythema; localized edema; heat; and the intensity/speed of onset/duration of pruritus to define a positive response to the vortex provocation test given their ease of execution and optimal inter-observer agreement.