BackgroundUndetected obstructive sleep apnea (OSA) is highly prevalent in patients undergoing bariatric surgery and increases perioperative risks. Screening for OSA using preoperative polygraphy (PG) with subsequent continuous positive airway pressure (CPAP) is costly and time-consuming. Postoperative continuous pulse oximetry (CPOX) is less invasive, and is hypothesized to be a safe and cost-effective alternative. ObjectivesThis nationwide multicenter prospective observational cohort study compared CPOX monitoring with OSA-screening using PG. SettingsHigh-volume bariatric centers. MethodsPatients were either postoperatively monitored using CPOX without pre-operative OSA-screening, or underwent pre-operative PG and CPAP treatment when OSA was diagnosed. Cohort placement was based on local hospital protocols. Cost-effectiveness was analyzed using quality adjusted life years (QALY) and healthcare costs. Surgical outcomes were also analyzed. Propensity score matching was used in sensitivity analyses. ResultsA total of 1390 patients was included. QALYs were similar between groups at baseline and one-year postoperatively. Postoperative complications, ICU-admissions and admissions, particularly OSA-related, did not differ between groups. Mean costs per patient/year in the CPOX group was €3,094 vs. €3,680 in the PG group; mean difference €-586 (95% CI €-933 to €-242). Following propensity score matching, 1090 of 1390 included patients remained, and similar findings for cost-effectiveness, complications and ICU admissions were observed. ConclusionCPOX monitoring without pre-operative OSA-screening was not associated with higher complication or readmission rates compared to PG. CPOX resulted in lower costs from a healthcare perspective and can therefore be considered a cost-effective alternative to routine OSA-screening in patients undergoing bariatric surgery.