Intradermal Tests With Drugs: An Approach to Standardization

Abstract

Background: Intradermal tests (IDTs) are performed and interpreted differently in drug allergy centers making valid comparison of results difficult.Objective: To reduce method-related and intercenter variability of IDTs by the introduction of a standardized method.Materials and methods: In 11 centers of the European Network for Drug Allergy, IDTs were prospectively performed with saline and with amoxicillin (20 mg/ml) using (1) the local method and (2) the standardized European Network in Drug Allergy (ENDA) method (0.02 ml). The diameters of the initial injection wheal (Wi) for the different volumes and sites injected obtained from each center were analyzed.Results: The most reproducible method was to fill a syringe with test solution, then expel the excess fluid to obtain exactly 0.02 ml. The median Wi diameter with 0.02 ml injection using the standardized method was 5 mm [range 2-10 mm; interquartile range (IQR) 5-5 mm; n = 1,096] for saline and 5 mm (range 2-9 mm; IQR = 4.5-5 mm; n = 240) for amoxicillin. IDT injection sites did not affect the Wi diameter. Training improved precision and reduced the variability of Wi diameters. Conclusion:Using the standardized IDT method described in this multicenter study helped to reduce variability, enabling more reliable comparison of results between individuals and centers.

Delabeling Delayed Drug Hypersensitivity: How Far Can You Safely Go?

“…Consensus on performance of intradermal testing (IDT) involves injection of 0.02-0.05 ml of the highest non-irritating drug concentration in a tuberculin syringe (0.5-1 ml) and needle gauge 25, 27 or 30 with reagent applied bevel-up, to the volar forearm of skin. (1) Using saline control and amoxicillin 20 mg/ml as their standard, the European Network for Drug Allergy (ENDA) recently performed a multicenter study of 11 sites in attempts to produce reproducible approaches that would reduce variability and standardize IDT to allow more reliable comparison between centers performing either immediate or delayed IDT (76). The definition of a positive delayed IDT has varied but in general is defined as an erythematous induration or swelling at the IDT injection site at 24 hours, 48 hours and out to 72 hours if negative at 48 hours (77,78).…”

“…The definition of a positive delayed IDT has varied but in general is defined as an erythematous induration or swelling at the IDT injection site at 24 hours, 48 hours and out to 72 hours if negative at 48 hours (77,78). Current guidelines recommend the use of IDT only with drugs available in sterile parenteral commercially manufactured preparations (76). In a recent consensus guideline there was agreement amongst international experts that delayed IDT using sterile preparations of drugs can aid drug allergy assessment and that similar to PT should not be performed sooner than 4-6 weeks following an acute reaction (1).…”

Criteria for intradermal skin testing and oral challenge in patients labeled as fluoroquinolone allergic

“…IDT to ciprofloxacin, levofloxacin, and moxifloxacin was performed -by European Network on Drug Allergy (ENDA) standardized technique -at concentrations of 0.025 mg/mL and 0.005 mg/mL, followed by single dose OC to the index FQ or other FQ (levofloxacin 250 mg, ciprofloxacin 250 mg, moxifloxacin 200 mg). 6 A 200 mg dose for moxifloxacin was used because it is only available as a 400 mg tablet. Oral challenge success was defined by the absence of any symptoms during an observed 2 hour challenge period.…”

In-Vitro Approaches to Predict and Study T-Cell Mediated Hypersensitivity to Drugs

“…A common, less hazardous approach is that of skin testing; multiple variations of skin testing exist, with the clinically utilised procedures being the skin prick test, intradermal test, patch test and photopatch test. These assays have seen clinical validation and are used routinely; for those seeking more comprehensive review of their utility, the authors refer readers to several specialist publications (27)(28)(29)(30)(31)(32)(33)(34). Despite uptake within clinical practice, all 3 of the described skin tests possess limited sensitivity and specificity, with variable values for each parameter reported in literature (28,35,36).…”