Diagnosing Allergic Contact Dermatitis Using Deep Learning: Single-Arm, Pragmatic Clinical Trial with an Observer Performance Study to Compare Artificial Intelligence Performance with Human Reader Performance

<u><b><i></i></b></u> <u><b><i>Background:</i></b></u> Allergic contact dermatitis is a common, pruritic, debilitating skin disease, affecting at least 20% of the population.<u><b><i>Objective:</i></b></u> To prospectively validate a computer vision algorithm across all Fitzpatrick skin types.<u><b><i>Methods:</i></b></u> Each participant was exposed to 10 allergens. The reference criterion was obtained 5 days after initial patch placement by a board-certified dermatologist. The algorithm processed photographs of the test site obtained on Day 5. Human performance in reading the photographs was also evaluated.<u><b><i>Results:</i></b></u> A total of 206 evaluable participants [mean age 39 years, 66% (136/206) female, and 47% with Fitzpatrick skin types IV-VI] completed testing. Forty-two percent (87/206) of participants experienced 1 or more allergic reaction resulting in a total of 132 allergic reactions. The model provided high discrimination (AUROC 0.86, 95% CI: 0.82-0.90) and specificity (93%, 95% CI: 92%-94%) but with lower sensitivity (58%, 95% CI: 49%-67%). Human performance interpreting the photographs ranged from providing similar performance to the algorithm to providing superior performance when combined across readers. There were no serious adverse events.<u><b><i>Conclusions:</i></b></u> The combination of a smartphone capture of patch testing sites with deep learning yielded high discrimination across a diverse sample.