The association between biomarker angiopoietin-like protein five and obstructive sleep apnea in patients undergoing bariatric surgery

Purpose: Obstructive sleep apnea (OSA) is prevalent in the bariatric population. OSA should be recognized in patients undergoing bariatric surgery preoperatively to prevent peri- and post-operative complications. Lipid metabolism-related biomarkers are associated with OSA. Triglyceride metabolism is, among others, regulated by angiopoietin-like protein five (ANGPTL5). We aimed to evaluate the level of ANGPTL5 in patients with OSA of different severity levels before and after bariatric surgery. Methods: We performed a single-center prospective cohort study including a consecutive series of patients who underwent bariatric surgery. We collected the clinical data, polysomnography (PSG) or polygraphy (PG) parameters, and plasma derived via venipuncture before and 6 to 12 months after surgery. Lipid profile, glucose levels, and ANGPTL5 levels were assessed. ANGPTL5 levels were measured using an enzyme-linked immunosorbent assay (ELISA). Results: The study included 88 patients for analysis. The patients were divided into two subgroups: no or mild OSA (apnea–hypopnea index (AHI) < 15 events/hour, n = 57) and moderate-to-severe OSA (AHI ≥ 15 events/hour, n = 31). The ANGPTL5 level was higher in the moderate-to-severe OSA group (20.5 [15.6, 26.5] ng/mL) compared to the no or mild OSA group (16.3 [12.5, 19.4] ng/mL) (p = 0.008). A significant positive correlation was observed between ANGPTL5 and AHI (ρ = 0.256, p = 0.017), apnea index (AI) (ρ = 0.318, p = 0.003), and triglyceride levels (ρ = 0.240, p = 0.025). ANGPTL5 levels were reduced significantly after bariatric surgery in both moderate-to-severe OSA (15.6 [10.3, 18.7] ng/mL) and no or mild OSA (13.4 [9.2, 15.8] ng/mL) groups, though to a lower level in the group without or mild OSA. Post-surgery, the significant positive correlation between ANGPTL5 and AHI (ρ = 0.210, p = 0.047), AI (ρ = 0.230, p = 0.034), and triglyceride (ρ = 0.397, p < 0.001) remained. Conclusion: The data showed increased levels of ANGPTL5 in patients with moderate-to-severe OSA. Both AHI and ANGPTL5 levels decreased significantly after bariatric surgery. We also report an association between ANGPTL5 levels and OSA severity.