Background: Obesity is an important predictor for development of obstructive sleep apnoea (OSA). Patients undergoing bariatric surgery are at increased risk of peri-operative morbidity from undiagnosed OSA. We aim to assess the prevalence and severity of OSA, and its association with the Epworth Screening Scale (ESS) in a bariatric surgical population.
Methods: Retrospective study of adult patients who attended the Tier 4 Medical Obesity Clinic (MOC) at Guys and St Thomas NHS Trust (GSTT) in 2018. Demographic characteristics, presence of concomitant medical comorbidities and the ESS score were captured. A home-based nocturnal pulse oximetry assessment was requested as part of the work-up prior to bariatric surgery. Severity of the OSA was defined according to the 4% oxygen desaturation index (ODI) and the respiratory physicians interpretation of the sleep study.
Results: 430 new cases were referred to the MOC throughout 2018. Of these, 44.9% (n=193) underwent an overnight pulse oximetry. The majority were female 146 (75.7%), aged 46.1±12.2 years and BMI of 44.0 kg/m2 (IQR 40.049.0). 35.2% (n=68) had a diagnosis of hypertension, 32.6% (n=63) of type 2 diabetes (T2DM) and 15.0% (n=29) of depression. Patients reported poor concentration 10% (n=20), nocturia 46% (n= 89) and snoring 45.5% (n=88). Median ESS score was 6 (IQR 311) suggestive of higher normal daytime sleepiness. 68.4% (n=132) of patients were diagnosed with OSA of any degree with 41.9% (n=81) having mild, 18.7% (n=36) moderate and 7.8% (n=15) severe OSA. 25.9% (n=50) patients were initiated on CPAP and 8.3% (n=16) were referred for mandibular advancement device. BMI was significantly associated with increased risk of OSA (OR 1.1, 95% CI 1.0 to 1.2; P<0.001). No significant differences in the ESS score in patients without OSA vs with OSA (6 IQR 311 vs 7 IQR 412, P=0.089) or degree of OSA (P=0.730).
Conclusion: OSA was noted to be highly prevalent in patients undergoing bariatric surgery. Thus, routine pre-operative oximetry screening may prove to be a cost-effective approach in this cohort of subjects.