Expert classification of hypospadias: an external validation and evaluation of agreement for Glans–Urethral Meatus–Shaft (GMS) and Hypospadias Objective Penile Evaluation (HOPE) scores

Purpose This study evaluates the inter-rater agreements of both the Glans–Urethral Meatus–Shaft (GMS) hypospadias score and Hypospadias Objective Penile Evaluation (HOPE) score, aiming to standardize disease classification for consistent agreement in clinically relevant characteristics of hypospadias. Methods Photos of hypospadias in children were collected from two separate institutions. Three raters scored the photos using GMS and HOPE, excluding penile torsion and curvature assessment in HOPE due to photo limitations. Results A total of 528 photos were included. With GMS, Fleiss’ multi-rater kappa showed an agreement of 0.745 for glans–urethral plate, 0.869 for meatus, and 0.745 for shaft. For HOPE scores, the agreements were 0.888 for position of meatus, 0.669 for shape of meatus, 0.730 for shape of glans, and 0.708 for the shape of the skin. The lower agreement in the shape of the meatus evaluation may be attributed to the lack of a quantitative classification method in HOPE. Experts rely on their subjective judgment based on the provided example photos and their index patient. Conclusions While there is high agreement among experts when evaluating hypospadias using the GMS and HOPE scoring criteria, only the position of the meatus achieved nearly perfect agreement highlighting that the current scoring systems entail a subjective element in disease classification.