Risk factors for androgenetic alopecia: a systematic review and meta-analysis

BACKGROUND: Androgenetic alopecia (AGA), the most common type of hair loss, is influenced by multiple factors. However, the associations between various risk factors and AGA remain controversial, with no systematic review or meta-analysis comprehensively analyzing these risk factors to date. METHODS: PubMed, Embase, and Cochrane databases were searched for observational studies reporting on AGA risk factors from inception through January 5, 2024. RESULTS: 31 studies involving 11,224 AGA cases and 36,825 controls were included. Family history (presence: odds ratio [OR] 2.72, 95% confidence interval [CI] 1.85–3.99; progression: OR 4.24, 95% CI 2.77–6.49) and smoking (presence: OR 1.46, 95% CI 1.06–2.01; progression: OR 1.60, 95% CI 1.29–1.99) were significantly associated with both presence and progression of AGA. A paternal family history of AGA (OR 2.22, 95% CI 1.59–3.10), insulin resistance (standardized mean difference [SMD] 0.40, 95% CI 0.27–0.53), and high fasting insulin levels (SMD 0.48, 95% CI 0.18–0.78) were also identified as factors that increased the risk of the presence of AGA. Alcohol consumption (OR 1.72, 95% CI 1.28–2.32), insufficient/poor quality sleep (OR 1.36, 95% CI 1.18–1.56), and overweight/obesity (OR 2.31, 95% CI 1.01–5.29) were related to the progression of AGA. Hypertension in men showed a significant correlation with AGA (OR 1.60, 95% CI 1.26–2.04). CONCLUSION: This meta-analysis identified several risk factors associated with AGA presence and progression, including a family history of AGA, smoking, alcohol consumption, insufficient or poor-quality sleep, overweight/obesity, hypertension in men, insulin resistance, and elevated fasting insulin levels. Future studies should explore the underlying mechanisms linking these factors to AGA.