Reliability of the Pattern Hair Loss Classifications: A Comparison of the Basic and Specific and Norwood–Hamilton Classifications

In the 2012 study involving 40 medical professionals (8 dermatological specialists, 17 dermatological residents, and 15 general physicians), the Basic and Specific (BASP) classification system was found to be more reliable and reproducible than the Norwood-Hamilton classification for pattern hair loss (PHL) when used to classify PHL in 100 sets of photographs of Korean male alopecia patients. The BASP classification, particularly the basic type (BA), demonstrated higher match rates for both intergroup reproducibility and intragroup repeatability compared to the Norwood-Hamilton classification, which also had limitations in its applicability to only male pattern hair loss and inability to classify certain types of baldness. The study concluded that the BASP classification is superior in terms of reliability and applicability to various hair loss patterns and both sexes.