A meta‐analysis study on the association between smoking and male pattern hair loss

BACKGROUND: Smoking-which often refers to recreational consumption of the nicotine-containing tobacco-is deemed a risk factor for both the development of and worsening of androgenetic alopecia (AGA). However, there is no published meta-analysis study on the effect of smoking on AGA; so, we quantitatively synthesized the evidence base pertaining to the recreational activity and this form of hair loss in men. METHODS: We systematically searched PubMed and Scopus to identify published studies with suitable data, and pairwise meta-analyses were conducted. RESULTS: Our search identified eight studies-and the data thereof were used across four meta-analyses. We found that ever smokers are significantly (p < 0.05) more likely, than never smokers, to develop AGA (pooled odds ratio (OR) = 1.82, 95% confidence interval (CI): 1.55-2.14). Our results showed that the odds of developing AGA are significantly (p < 0.05) higher in men who smoke at least 10 cigarettes per day, than in their counterparts who smoke up to 10 cigarettes per day (pooled OR = 1.96, 95% CI: 1.17-3.29). For men with AGA, the odds of disease progression are significantly (p < 0.05) higher among ever smokers than in never smokers (pooled OR = 1.27, 95% CI: 1.01-1.60). We found no significant (p ≥ 0.05) association between smoking intensity and disease progression. CONCLUSIONS: Findings from the current study-which is the first meta-analysis to our knowledge reviewing the association between AGA and the extent of smoking, can guide further research and update clinical practice guidelines.