Smoking Status and Psoriasis Risk: An Updated Systematic Review and Meta-Analysis.

INTRODUCTION

Psoriasis is a chronic immune-mediated inflammatory skin disease affecting 1-5% of the global population. Smoking has long been implicated as a potential environmental risk factor; however, previous studies and meta-analyses have reported heterogeneous and sometimes inconsistent findings. Since the publication of earlier reviews, several large population-based studies have become available, warranting an updated and more comprehensive synthesis of the evidence.

METHODS

A systematic search of PubMed, Embase, and the Cochrane Library was conducted from database inception to August 8, 2025, following PRISMA guidelines. Cohort, case-control, and cross-sectional studies evaluating the association between smoking status (current or former) and psoriasis risk were included. Adjusted odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled using fixed- or random-effects models according to heterogeneity. Subgroup, sensitivity, and publication bias analyses were performed.

RESULTS

Sixteen studies were included in the analysis. Both current and former smoking were associated with an increased risk of psoriasis. The pooled OR was 1.89 (95% CI: 1.50-2.39) for current smokers and 1.45 (95% CI: 1.25-1.68) for former smokers, with significant heterogeneity observed across studies. Regional differences were noted: in Asia, the risk for current smokers was notably higher (OR = 2.19, 95% CI: 0.96-4.99), while in Europe and America, the risk for former smokers was higher (Europe: OR = 1.62, 95% CI: 1.46-1.79; America: OR = 1.39, 95% CI: 1.28-1.52). Sensitivity analyses supported the robustness of the findings, and regional variability in the relationship between smoking and psoriasis risk was observed.

CONCLUSION

This updated meta-analysis provides consolidated evidence that smoking is associated with an increased risk of psoriasis, particularly among current smokers. The findings reinforce smoking as a relevant, modifiable risk factor and support its consideration in psoriasis prevention and public health strategies.