Effectiveness of Combination Therapy (Topical and Phototherapy) Versus Monotherapy (Phototherapy Alone) in the Treatment of Moderate to Severe Plaque Psoriasis: A Systematic Review and Meta-Analysis

Phototherapy remains an important treatment option for moderate-to-severe plaque psoriasis, but monotherapy may be limited by incomplete response, repeated treatment sessions, and cumulative ultraviolet exposure.This systematic review and meta-analysis evaluated the effectiveness and safety of topical therapy combined with phototherapy versus phototherapy alone.The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines and included randomized controlled trials identified through database searches up to June 2025.Fifteen randomized clinical trials (RCTs) met the eligibility criteria.For Psoriasis Area and Severity Index (PASI) improvement, three studies provided comparable continuous data, and the pooled effect was not statistically significant (standardized mean difference or SMD=0.26;95% CI, -0.31 to 0.84; p=0.37;I² =51%).Six studies contributed withdrawal data, with no significant difference between groups (Odds ratio or OR=0.98; 95% CI, 0.32 to 2.98; p=0.97;I² = 0%).Three studies contributed local skin adverse-event data, which favored monotherapy (OR=2.35;95% CI, 1.05 to 5.26; p=0.04;I² = 38%).Individual trials frequently reported faster improvement, fewer treatment sessions, or lower cumulative ultraviolet exposure with combination therapy, but these findings were not uniform.Overall, combination therapy may improve treatment efficiency in selected patients, although local skin reactions may be more frequent and the evidence is limited by small studies, heterogeneous regimens, and short follow-up.