Towards a consensus on how to diagnose and quantify female pattern hair loss - The 'Female Pattern Hair Loss Severity Index (FPHL-SI)'.

Background: Female pattern hair loss (FPHL) is a common non-scarring alopecia characterized by widening of the midline hair part at the crown (vertex). In 1977, Ludwig developed a scale that graded the degree of visible vertex hair thinning from I (least severe) to III (most severe). However, by the time patients exhibit the full manifestations of 'Ludwig I', they have already lost a significant volume of hair. Although current therapies may realistically halt progression of hair loss, improvements in hair density is often more limited. Identification and grading of FPHL at an earlier stage is desirable to institute appropriate therapy before significant hair loss has occurred and to enable monitoring over time.

Aim: To generate consensus guidance for the recognition and quantification of FPHL that can be used in the clinic.

Methods: Nine clinicians from Europe, North America and Australia experienced in the management of FPHL developed this scale by consensus.

Results: We propose a three-point severity scale (termed the FPHL Severity Index (FPHL-SI)) that combines validated measures of hair shedding, midline hair density and scalp trichoscopy criteria to produce a total FPHL-SI score (maximum score = 20). The score is designed to grade FPHL severity over time, while being sufficiently sensitive to identify early disease. A score of 0-4 makes FPHL unlikely; a score of 5-9 would indicate early-stage FPHL, with higher scores indicating greater disease severity.

Conclusions: As a starting point for further public debate, we employ criteria already used in clinical practice to generate a pragmatic FPHL grading system (FPHL-SI) of sufficient sensitivity to identify and monitor early FPHL changes. This may have to be further optimized after systematic validation in clinical practice.