Table 1.

Comparison of previous meta-analyses and the present study.

Study	Exposure	Search end date	Included studies/designs	Dose-response	Smoking cessation	Subtype-specific outcomes	Key difference from the present study
Armstrong 2013	Smoking	15 Jun 2013	25 prevalence studies + 3 incidence studies	Limited/no formal pooled analysis	No	No formal pooled subtype analysis	Focused mainly on prevalence, with limited evidence on incident psoriasis
Zhou 2020	Smoking	12 Apr 2020	Cohort and case-control studies	No formal pooled analysis	Limited	PPP and PsA discussed separately	Smoking-focused review without integrated smoking-alcohol synthesis or detailed multi-metric dose-response analysis
Brenaut 2013	Alcohol	Up to Dec 2011	Heterogeneous observational studies	No	No	No	Systematic review only; no quantitative pooled meta-analysis for alcohol risk
Zhu 2012	Alcohol	Up to 2012	Case-control studies only	No	No	No	Early alcohol meta-analysis restricted to case-control studies and not focused on incident psoriasis
Present study	Smoking and alcohol	18 Dec 2025	Cohort, case-control, nested case-control, and twin studies	Yes	Yes(exploratory)	Yes (PPP, PsA)	Updated synthesis emphasizing incident/newly diagnosed psoriasis, with smoking dose-response analysis and exploratory analyses of cessation and subtype-specific outcomes

Differences in the number of included studies across reviews partly reflect differences in eligibility criteria, particularly the present review's emphasis on incident or newly diagnosed psoriasis where possible and exclusion of case–case analyses from the primary quantitative synthesis.