Efficacy and safety of fractional CO2 laser therapy combined with triamcinolone acetonide injection for hypertrophic scar: a preliminary systematic review and meta-analysis

Background This study aims to systematically evaluate the efficacy and safety of fractional CO 2 laser therapy combined with triamcinolone acetonide (TA) injection for hypertrophic scar (HS). Materials and methods Randomized controlled trials (RCTs) investigating the combination therapy of fractional CO₂ laser and TA injection for HS were identified through systematic searches of PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Wanfang, Sinomed, and VIP databases from inception to December 2024. The risk of bias was assessed using the Cochrane Collaboration’s Risk of Bias tool. Meta-analysis was performed with RevMan (version 5.3), while sensitivity analysis and publication bias assessment were conducted using Stata (version 14.0). The quality of evidence for outcomes was evaluated with the Grades of Recommendations, Assessment, Development, and Evaluation (GRADE) assessment. Results Nineteen studies involving 1,775 patients were included in this meta-analysis. Compared with TA injection alone, the pooled results showed that fractional CO₂ laser combined with TA injection significantly reduced Vancouver Scar Scale scores MD: −2.52, 95% CI: −3.07 to −1.98, p 0.00001, pruritus scores MD: −0.86, 95% CI: −0.94 to −0.78, p 0.00001, pain scores MD: −1.04, 95% CI: −1.38 to −0.71, p 0.00001, scar thickness SMD: −2.36, 95% CI: −3.12 to −1.61, p 0.00001, serum TGF-β1 level SMD: −2.09, 95% CI: −2.71 to −1.46, p 0.00001, serum VEGF level SMD: −2.03, 95% CI: −2.90 to −1.17, p 0.00001, serum EGF level MD: −17.38, 95% CI: −20.94 to −13.82, p 0.00001, and serum TNF- α level SMD: −1.81, 95% CI: −2.77 to −0.85, p = 0.0002. Regarding safety, the combination of fractional CO₂ laser and TA injection reduced the incidence of skin atrophy RR: 0.52, 95% CI: 0.34 to 0.80, p = 0.003 compared to TA injection alone. There was no significant difference between the two groups in the incidence of adverse events, including folliculitis RR: 0.64, 95% CI: 0.30 to 1.35, p = 0.24, erythematous edema RR: 1.21, 95% CI: 0.68 to 2.16, p = 0.52, skin allergies RR: 0.38, 95% CI: 0.14 to 1.05, p = 0.06, pigmentation RR: 1.12, 95% CI: 0.58 to 2.16, p = 0.73, ulcers RR: 0.35, 95% CI: 0.11 to 1.16, p = 0.09, infections RR: 1.45, 95% CI: 0.29 to 7.17, p = 0.65, and blisters RR: 0.33, 95% CI: 0.01 to 7.88, p = 0.50. Conclusion Preliminary evidence suggests that fractional CO₂ laser combined with TA injection is an effective treatment for HS. However, due to methodological limitations in the included studies, large-scale, rigorously designed RCTs are required to validate these findings. Additionally, all 19 RCTs were conducted in China with Chinese participants; therefore, the current evidence is limited to this population and requires validation in other ethnic groups. Systematic Review Registration https://www.crd.york.ac.uk/PROSPERO/view/CRD42025630116 , identifier PROSPERO (CRD4202563011).