University of Southern Denmark Sleep apnoea in patients undergoing bariatric surgery Lage-Hansen,

INTRODUCTION: The objective of this study was to investigate the presence of obstructive sleep apnoea (OSA) among patients awaiting bariatric surgery and to evaluate if a change in symptoms and clinical measurements of OSA was seen one year after bariatric surgery. METHODS: Patients awaiting bariatric surgery in the Region of Southern Denmark were invited to participate in an OSA examination during a 15-month period (2012-2013) using the Embletta device for cardiorespiratory monitoring before and one year after bariatric surgery. The Apnoea-Hypopnoea Index (AHI), weight, BMI and the Epworth Sleepiness Score (ESS) were measured prior to and one year after surgery. RESULTS: A total of 56 patients were enrolled in the study, and 59% were found with OSA (AHI ≥ 5). Thirty-six patients were eligible for examination one year post-operatively. Twelve of these patients did not have OSA (AHI < 5) either at inclusion or at re-examination. In the remaining 24 patients with OSA, the BMI dropped from 44.4 prior to surgery to 30.8 kg/m2 one year after surgery (p < 0.01). Mean AHI decreased from 12.8 prior to surgery to 3.7 one year after surgery (p < 0.01). There was no effect of weight reduction on the ESS. CONCLUSIONS: A statistically significant reduction in AHI was seen in patients with OSA one year after surgery. No statistical differences were observed for ESS. FUNDING: This study was funded by “Fonden for Lægevidenskabelig Forskning m.v. ved sygehusene i Region Syd” and by ”Edith og Vagn Hedegaard Jensen fond”. TRIAL REGISTRATION: ClinGov (ID: S-20120004jln). Obstructive sleep apnoea (OSA) is a clinical condition characterised by obstruction of the upper airways following sleep-induced reduction of muscle tone, specifically in and around the tongue and pharynx. During the resulting apnoea, mounting hypoxaemia increases the inspiratory drive in the respiratory centre and eventually causes arousal. Although usually not fully awakened, the arousal deprives the patient suffering from OSA of both REMand non-REM-sleep [1]. The OSA patient may gradually develop associated symptoms. Daytime sleepiness is frequently recognised and associated with an elevated risk of motor vehicle accidents. In severe cases, OSA may be complicated by hypertension, cardiovascular disease, stroke, decreased cognitive function and a diminished quality of life [2, 3]. OSA is graded by the Apnoea-Hypopnoea Index (AHI). AHI is the sum of apnoea and hypopnoea incidents during one hour of sleep. The severity of OSA is graded by the AHI into mild (5 ≤ AHI < 15), moderate (15 ≤ AHI < 30) or severe (30 ≤ AHI) [4]. Obesity is an important predisposing factor for OSA [5]. Studies report that the prevalence of OSA in patients undergoing bariatric surgery varies between 60% and 92% [6, 7]. In 46-58% of cases, the OSA can be classified as moderate to severe [6]. In Denmark, OSA is one of the criteria for performing bariatric surgery, but very few patients are actually referred to bariatric surgery for this reason. The literature has shown that bariatric surgery has a significant effect on sleep apnoea, inducing resolution or improvement in the majority of cases [7-17]. Metaanalyses reported a decrease of AHI by 29 per hour following bariatric surgery in 525 subjects with a mean preintervention BMI of 51 [18]. Previous studies often show a high number of dropouts, which dropout generally exceeding 60% [7-17]. To the authors’ knowledge, no Scandinavian studies have previously investigated the effect of bariatric surgery on sleep apnoea. The aim of this study was to investigate the frequency of OSA among patients undergoing bariatric surgery and the effect of surgery on OSA in a group of Danish bariatric patients. MATERIAL AND METHODS Study design and setting The study was cross sectional and prospective with systematic data collection from the Bariatric Surgery Clinic in the Region of Southern Denmark. In the 15-month period from March 2012 to June 2013, all patients awaiting bariatric surgery were invited to participate in the study. All invited participants fulfilled the Danish national guide line criteria for referral to bariatric surgery, which were: age > 25 years and BMI > 35 kg/m2 plus at least one obesity-related complication or a BMI > 50 kg/ m2. All included patients had undertaken an 8% voluntary weight loss driven by dietary restriction in the course of a 3-6-month period before their surgery, as required by guidelines for patients subject to public payment. Sleep apnoea in patients undergoing bariatric surgery Philip Rask Lage-Hansen1, Jesper Holm2, Jeppe Gram1 & Knud Larsen2