Reliability of the pattern hair loss classifications: A comparison of the basic and specific and Norwood–Hamilton classifications

Abstract

Pattern hair loss (PHL) is the most common form of baldness in both sexes. The Norwood-Hamilton classification is the most commonly used classification worldwide, but it has many limitations. The basic and specific (BASP) classification was introduced as an improvement over the Norwood-Hamilton classification. Previous research was done to estimate the reliability of the Norwood-Hamilton classification and the result was unsatisfactory. However, the reliability of the BASP and Norwood-Hamilton classifications has not yet been compared. Eight dermatological specialists, 17 dermatological residents and 15 general physicians classified PHL in 100 sets of photographs using both the BASP and Norwood-Hamilton classifications. Intergroup reproducibility was evaluated by examining the match rate of the individual data in each group and the match rate between hair specialist and the other examiners. Intragroup repeatability was determined by calculating the match rate between the first and second studies. In terms of intergroup reproducibility of the match rate for individual data in each group, the basic type had the best agreement, the specific type had the second best, and the Norwood-Hamilton classification had the lowest match rate. In comparison, hair specialist and intragroup repeatability showed the same patterns. The BASP classification not only distinguishes all kinds of hair loss patterns, but also has better reproducibility and repeatability than the Norwood-Hamilton classification.

Setting reference values in trichology

“…So far, the problem has not been solved. Moreover, particularly in papers published by epidemiologists, reference is constantly made to the old Hamilton scale, which has been shown to be poorly reproducible …”

“…Moreover, particularly in papers published by epidemiologists, reference is constantly made to the old Hamilton scale, which has been shown to be poorly reproducible. 1,2 The difficulty in setting up reference values in human trichology depends mostly on the presence of AGA, which is well known to affect both hair density and thickness. AGA is largely widespread among adult Caucasians so much so that if one reads normality as averageness, the normal subjects should be the bald people rather than the hairy ones.…”

A semiquantitative grading scale for frontal and vertex of androgenetic alopecia

“…The most widely used clinical classifications to AGA include Hamilton–Norwood scale, Ludwig scale, and BASP classification. Previous studies have shown the higher concordance and repeatability of BASP classification than Hamilton–Norwood classification . On these bases, we further developed a detailed and objective quantitative grading scale.…”

Evaluation of Five Hundred Patients using Ahmad’s NPRT System for Documenting Male Pattern Baldness

“…A Chinese study showed different ratios in various cities of china [21] . Among various classification system of hair loss, the reliability of Norwood systems vs. basic and specific patterns (BASP) have been compared which concluded that BASP was better than Norwood's classification [23] . However there are certain limitations in BASP classification too, i.e., certain types of fronto-parietal and vertex regions (F2, F3) are confused with type v. and type V of BASP is confused with Type V in Norwood system.…”