Frequency of the Types of Alopecia at Twenty-Two Specialist Hair Clinics: A Multicenter Study

<jats:p>&lt;b&gt;&lt;i&gt;Background:&lt;/i&gt;&lt;/b&gt; The frequency of different types of alopecia is not clearly reported in recent studies. &lt;b&gt;&lt;i&gt;Objective:&lt;/i&gt;&lt;/b&gt; To analyze the frequency of the types of alopecia in patients consulting at specialist hair clinics (SHC) and to assess for global variations. &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; Multicenter retrospective study including data from patients evaluated at referral SHC in Europe, America, Africa and Australia. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; A total of 2,835 patients (72.7% females and 27.3% males) with 3,133 diagnoses of alopecia were included (73% were non-cicatricial and 27% were cicatricial alopecias). In all, 57 different types of alopecia were characterized. The most frequent type was androgenetic alopecia (AGA) (37.7%), followed by alopecia areata (AA) (18.2%), telogen effluvium (TE) (11.3%), frontal fibrosing alopecia (FFA) (10.8%), lichen planopilaris (LPP) (7.6%), folliculitis decalvans (FD) (2.8%), discoid lupus (1.9%) and fibrosing alopecia in a pattern distribution (FAPD) (1.8%). There was a male predominance in patients with acne keloidalis nuchae, dissecting cellulitis and FD, and female predominance in traction alopecia, central centrifugal cicatricial alopecia, FFA, TE, FAPD and LPP. &lt;b&gt;&lt;i&gt;Conclusion:&lt;/i&gt;&lt;/b&gt; AGA followed by AA and TE were the most frequent cause of non-cicatricial alopecia, while FFA was the most frequent cause of cicatricial alopecia in all studied geographical areas.</jats:p>