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

Abstract

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. We systematically searched PubMed and Scopus to identify published studies with suitable data, and pairwise meta-analyses were conducted. 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. 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.