Abstract: 【Abstract】 Objective To investigate the optimal timing of oral propranolol treatment for proliferative infantile hemangiomas （IH）. Methods A bidirectional cohort study was conducted. Infants with proliferative IH receiving oral propranolol treatment were collected from the Department of Pediatric Surgery, West China Hospital, Sichuan University between June 2015 and May 2019, and their general information and IH-related clinical data were analyzed. The primary outcome was the satisfactory regression rate of IH during 6–12 months of continuous oral propranolol treatment; secondary outcomes included the time to achieve satisfactory regression, incidence of adverse reactions, incidence of IH ulceration, and IH recurrence rate. Multivariate logistic regression was performed to identify factors influencing the satisfactory regression of IH after propranolol treatment, and a receiver operating characteristic （ROC） curve was employed to determine the optimal age for initiating propranolol therapy. Results A total of 122 IH infants were enrolled in the study, including 32 males （26.2%） and 90 females （73.8%）, with ages （M［Q1, Q3］） of 8.6 ［6.3, 12.3］ weeks. IH was located on the head and face in 56 cases （45.9%）. There were 57 cases （46.7%） of localized IH, 53 （43.4%） of segmental IH, and 86 （70.5%） of mixed-type IH. Ulceration occurred in 17 cases （13.9%）. After 6 months of propranolol treatment, 8 patients （6.6%） experienced treatment failure, and 12 （9.8%） experienced relapse within 6 months after discontinuation of propranolol. During 6 months of oral propranolol treatment, 56 infants （45.9%） experienced mild to moderate adverse reactions, with no drug-related deaths observed. Multivariate logistic regression analysis revealed that the age at initiation of propranolol treatment was an independent factor influencing satisfactory regression of IH （OR = 0.879, 95% CI: 0.808–0.957）. ROC curve analysis revealed that the optimal age for starting propranolol therapy was 9.9 weeks, with a sensitivity of 75.7% and a specificity of 61.5%. Infants aged ≤ 9.9 weeks （73 cases） had a significantly higher satisfactory regression rate （72.6% ［53/73］） compared with those aged > 9.9 weeks （49 cases, 34.7% ［17/49］; χ2 = 17.23, P < 0.001）; the time to achieve satisfactory regression of IH was significantly shorter in the infants aged ≤ 9.9 weeks （M［Q1, Q3］: 46.0 ［38.5, 48.0］ weeks） than in those aged > 9.9 weeks （57.0 ［40.0, 73.5］ weeks; Z = -2.01, P = 0.045）. Conclusion For IH infants requiring systemic therapy, initiation of oral propranolol before the age of 10 weeks appeared to improve the satisfactory regression rate of IH.

Key words: Hemangioma, Infantile hemangioma, Propranolol, Treatment timing, Influencing factor, Age