Screening for allergic contact dermatitis based on pattern of patch test results: A retrospective study

Background: Contact allergies are associated with morbidity worldwide. Purpose: To investigate the patterns of sensitization to contact allergens in a local population. Methods: A retrospective study investigated patch test reactivity among patients with a clinical diagnosis of contact dermatitis referred to the dermatology clinic at King Fahad Armed Forces Hospital, Jeddah, between January 2021 and January 2023. Pregnant women, immunosuppressed patients, and those receiving immunosuppressive therapy were excluded. Only 92 of 101 referred patients underwent patch testing after fulfilling requirements. The patch test was performed using a Thin-layer Rapid-Use Epicutaneous patch test containing 35 contact allergenic elements and one control (total = 36). Results: Among 92 patients, 35 (38%) were males, and 57 (62%) were females. Of these, 62 (67.4%) patients had a positive patch test and reacted to one or more allergens. The most common sensitizing allergens were p-phenylenediamine (PPD), gold sodium thiosulfate, and disperse blue 106, with equal positive reactions in 16 (25.8%) patients, followed by nickel sulfate in 13 (21%), p-tert-butylphenol formaldehyde resin in eight (13%), fragrance mix in 7 (10.8%), and epoxy resin in six (9.2%) patients. No significant sex differences were found among patients with contact dermatitis where notable patch test allergen reactivity was observed. Conclusion: Patch test reactivity to PPD, gold sodium thiosulfate, and disperse blue 106 was high. The pattern of contact allergy observed here highlights the need for large-scale investigations to identify local allergens for contact allergy and formulate policies for avoiding exposure.