INTRODUCTION: Pectus excavatum (PE) is the most common congenital chest wall deformity. The vacuum bell (VB) is a nonoperative alternative to surgical correction. We reviewed our center's experience with VB for PE to identify variables associated with improved therapeutic success, with a focus on compliance to prescribed VB therapy. METHODS: We conducted a single-center retrospective review of patients with PE who initiated VB therapy from August 2020 to August 2023. Patients who were fully compliant with therapy (defined as 28 h/week) were compared to patients who were noncompliant (<
27 h/week). Multivariable linear regression was used to identify factors predictive of pectus excavatum depth (PED) correction. RESULTS: Fifty-seven patients (86% male) initiated VB therapy. Of these, 22 patients (38.6%) were compliant with prescribed VB usage and 35 (61.4%) were noncompliant. There was a significant difference in PED correction between compliant and noncompliant groups (28.0% versus 16.0%, P <
0.001). Hours of VB usage per week was the strongest predictor of PED correction (P = 0.023). Days of treatment and lower initial Haller index also significantly predicted PED correction (P = 0.036 and P = 0.043, respectively), while height, weight, age, sex, and initial PED were not significant predictors. CONCLUSIONS: Although age and initial PED are thought to affect VB efficacy, our data demonstrates that when compliance with therapy is factored, these variables do not significantly predict therapeutic success. Therefore, for a highly compliant patient, VB therapy can be effective regardless of age or severity.