3090 Fric test in dermographism

Friday, 16 October 2015
Hall D1 Foyer (Floor 3) (Coex Convention Center)

Kiran Godse, MD.FRCP , Dermatology, D.Y.Patil Medical College and Hospital, NAVI MUMBAI, India

This instrument is known as the Fric Test or friction test dermatographometer (BiomedizinischeWekstatte der Charite, Berlin, Germany).  It is a flat, rectangular plastic template with four smooth plastic tips of varying lengths (2.5 mm, 3.0 mm, 3.5 mm, and 4.0 mm), set 2 cm apart. Each tip is about 3 mm in diameter with a slightly rounded end.

Thirty diagnosed adult cases (18Females and 12 Males) of symptomatic dermatographism (on the basis of history and clinical findings) were enrolled in the study after obtaining a written informed constent.Likewise, thirty patients with no active pruritic skin disease were allocated to the control group.Patients on antihistamines, steroids, and otherimmunosuppresants were excluded from the study as were children, pregnant females, and those unwilling to be enrolled.

The results of the utility of the Fric test over the traditional ball point pen test were quite remarkable.  out of the 30 subjects who had voluntarily enrolled in our study, an astounding 28 (93%) of them displayed a positive Fric test, which is defined as one which produces a wheal of more than 1 centimeter diameter with at least one tip. Unsurprisingly, only 3 (10%) of the 30 individuals generated a positive Fric test (all positive with the 4 mm tip length) in our control group. The comparative results with different tip lengths in patients with a positive Fric test were also recorded and tabulated . As expected, the length of the tip of the instrument positively correlated with the probability of a positive test. All of the subjects were positive with 4 mm length but only 14% showed positivity for the 2.5 mm length.

When the same procedure was carried out using a ball point pen on the left forearm, 18 (60%) out of the 30 subjects developed a positive ball point pen test (development of a wheal of more than 1 centimeter diameter within 10 minutes after provocation), whilst a mere 4 (13.3%) out of the 30 individuals developed a wheal in our control group.

With the advent of the Fric test, many of drawbacks of ball point pen can possibly be eliminated.Thus the practicing clinician could assess the severity of the disease and the response to treatment without taking recourse to more expensive investigations.

Fric test is useful instrument for assessing severity of symptomatic dermographism.