Supplementary Material for: A comparative cross-sectional study of hair density, hair shaft diameter of different severities of anterior scalp marginal traction alopecia in women.

Introduction: Hair density (HD) studies of marginal traction alopecia (MTA) are few. We aimed to document the HD/cm2, number of hair shafts (HS) per pilosebaceous unit (PU) and HS diameter of different grades of anterior scalp margin MTA (AMTA).
Methods: A cross-sectional descriptive study of 401 women over a 9-months period in 2023. The severity of AMTA was scored using the marginal traction alopecia severity score (M-TAS). Phototrichoscopic evaluation of HD/cm2, HS diameter and number of HS) per PU was done on the alopecic intertemporal, right and left temporal and, the non-alopecic right temporal and intertemporal scalp sites.
Results: The HD/cm2 of the non-alopecic intertemporal scalp site ranged from 282-519 cm2 compared to that of the AMTA which ranged from 14-349/cm2, p<0.001. With increasing severity of AMTA, there was a significant decrease in HD: Grade 1 had HD of 227.56/cm2 compared to 131.22/cm2 in grade 4 at the intertemporal area, p<0.001. HS diameter ranged from 0.0087-0.0200mm in Grade 1 and 0.0078 – 0.0100 in Grade 4. Single hair units in 100%.
Conclusion: Anterior scalp marginal alopecia results in a significant reduction of hair density, hair shaft diameter and number of hair strands. Preventative education on hair care practices and hair styles is advocated.