Improving povidone‐iodine and iodine preparations for patch testing. (3rd January 2021)

• Record Type: Journal Article
• Authors: Forkel, Susann; Beutner, Caroline; Amschler, Katharina; Schröder, Silke Sabina; Schön, Michael P.; Geier, Johannes; Buhl, Timo
• Is Part Of: Contact dermatitis. Volume 84:Number 5(2021)
• Page Start: 332
• Page End: 337
• Publication Date: 2021-01-03
• Subjects: antiseptics -- contact hypersensitivity -- iodine -- povidone‐iodine; Contact dermatitis -- Periodicals; 616.51
• DOI: 10.1111/cod.13760
• Languages: English
• ISSNs: 0105-1873

Abstract

Abstract: Background: Allergy evaluation by patch testing with povidone‐iodine (PVP‐I) or iodine remains challenging, because current patch test preparations frequently lead to false‐positive or irritant skin reactions. Objectives: To investigate different preparations for iodine patch tests and to assess their clinical relevance with repeated open application tests (ROATs). Methods: We monocentrically analyzed 95 patients with suspected allergy to disinfectants in retrospect who underwent parallel iodine patch testing with four preparations: PVP‐I 2% aq., 5% aq., 10% aq., and iodine 0.5% pet. Results: In 27 of 95 patients (28.4%), we found positive reactions to one of the four test preparations. After ROATs in 22 of these 27 positively tested individuals, only one patient was diagnosed with iodine allergy. In contrast, 31 of 95 patients (32.6%) showed irritant or questionable patch test reactions on day 2 (D2) and/or D3 and/or D7 to one or more test preparations. Testing with PVP‐I 2% aq. resulted in the lowest number of doubtful skin reactions while detecting the single allergic patient. Conclusion: PVP‐I 2% aq. was found to be the optimal patch test preparation. In general, iodine allergy appears to be substantially overestimated, and positive patch test responses to iodine should prompt an urgent ROAT for confirmation before diagnosing iodine allergy. Highlights: Almost all antiseptics have irritant properties. Patch testing with povidone‐iodine (PVP‐iodine) 10% aq. regularly results in a high number of false‐positive and irritant reactions. Testing with PVP‐iodine 2% aq. seems to be an adequate. Relevance confirmation by repeated open application tests (ROATs) after positive patch tests with PVP‐iodine is strongly recommended.