Prevalence and gender distribution of trichotillomania: A systematic review and meta-analysis.

Epidemiological studies have provided varying prevalence estimates of trichotillomania (TTM) and other hair-pulling behaviors. We performed a systematic review and meta-analysis to provide data-driven prevalence estimates of TTM and hair-pulling. PubMed, PsycInfo and Embase were searched on June 2020 (updated in November 2021). Studies reporting the frequency of TTM defined by Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria or hair-pulling behaviors were included. Prevalence data was extracted for both genders, and female-to-male odds ratios (OR) were computed for TTM and any hair-pulling behaviors. Data were pooled through random-effects meta-analyses. Of the 713 records identified through database searches, 30 studies involving 38,526 participants were included. Meta-analyses indicated TTM had a prevalence of 1.14% (95% CI 0.66%, 1.96%), while any hair-pulling behavior had a prevalence of 8.84% (95% CI 6.33%, 12.20%). Meta-analyses demonstrated females were at an increased risk of any hair-pulling when noticeable hair loss was required (OR = 2.23, 95% CI 1.60, 3.10, p < 0.0001), but not of any hair-pulling when noticeable hair loss was not required (OR = 0.90, 95% CI 0.72, 1.64, p = 0.33). Meta-analyses did not indicate female preponderance in TTM (k = 10; N = 22,775; OR = 1.29; 95% CI 0.91, 1.83; I = 28%, p = 0.15), although there was considerable heterogeneity across studies. This study demonstrates that TTM impacts ∼1% of the population, while general hair-pulling behaviors affects ∼8%, highlighting the significant public health impact of this understudied condition. Additional research should clarify the gender distribution of TTM in epidemiological samples.