Inter‐rater variability and consistency within four acne grading systems recommended in China, USA, and Europe

To investigate the correlation among different investigators (intrarater variation) in the assessment of acne vulgaris severity using Acne Grading System (AGS), International Improvement Grading System (IIGS), Investigator Global Assessment of acne (IGA), and Global Evaluation Acne (GEA), and to compare AGS and IIGS with the IGA recommended in the United States, and GEA in Europe.A prospective cross-sectional study was conducted among patients with acne vulgaris, attending the dermatology outpatient clinics at five hospitals in China. Four investigators were engaged using AGS, IIGS, IGA, and GEA to assess severity of acne vulgaris. Correlation among AGS, IIGS, GEA, and IGA were analyzed.A total of 1107 participants suffering from acne vulgaris were enrolled. There was evidence of adequate internal consistency among AGS, IIGS, IGA, and GEA. For the intrarater reliability, AGS, IIGS, GEA, and IGA demonstrated excellent reliability. Moreover, AGS, IIGS, IGA, and GEA were significantly correlated with each other (p ≤ 0.01).IIGS and AGS were reliable, and correlated well with IGA and GEA.