Effect of Laparoscopic Roux-en-Y Gastric Bypass Surgery on Obstructive Sleep Apnea in a Chinese Population with Obesity and T2DM

Obstructive sleep apnea (OSA) is one of the most common sleep disturbances; it affects 3.2–20 % of the adult population [1, 2] and has a negative impact on public health, increasing both morbidity and mortality [3]. Although continuous positive airway pressure (CPAP), oral appliances, and surgical modifications of the airway are considered parts of the routine management of patients with OSA, there remain many problems with these treatments in practice. Nasal CPAP is considered the gold standard therapy for OSA [4]. However, reported CPAP compliance rates vary from 34 to 85 % [5, 6], which might limit the therapeutic value for OSA patients over the long term. Oral appliances are generally viewed as being less efficacious than treatment with CPAP [7, 8]. Moreover, 6–86 % of patients who used oral appliances have been reported to experience adverse effects, including dryness of the tongue and throat, pain in the teeth and jaw, and insomnia [7, 9]. Various surgical techniques of the upper airway have been used to treat OSA, although the use of surgery for this condition remains somewhat controversial and is associated with limited and unpredictable efficacy that may diminish over the long term [10–12]. That is, although several treatments exist, they are often poorly tolerated or only partially alleviate the abnormalities. Thus, there is a need to improve patient adherence to existing treatments and to develop new treatments.

Bariatric surgery, which is currently the most effective treatment for morbid obesity, has been reported as a novel therapeutic treatment option for OSA [13]. The effect of bariatric surgery on OSA has been reported to be encouraging [14, 15]. However, these published series have not included diverse populations, especially in developing countries. Moreover, whether bariatric surgery is applicable to patients with OSA and other complications, such as obesity and type 2 diabetes mellitus (T2DM), should be determined.

Given the significant morbidity and mortality associated with OSA and the potential therapeutic value of bariatric surgery, we conducted a follow-up study of the effect of laparoscopic Roux-en-Y gastric bypass (LYGB) surgery in a Chinese obesity population with both OSA and T2DM.

In total, 72 Chinese patients with obesity and T2DM were recruited for the study. After the first PSG test, 18 subjects were excluded because of AHI <5. The remaining 54 patients with T2DM and OSA were included in the follow-up study. All participants were asked to undergo a second PSG test at least 6 months after surgery. However, ten patients were excluded because of lost to follow-up, or refusing to take the second PSG test (Fig. 1). However, the anthropometric data and sleep recording data from their first visit were similar (p > 0.05) to those of the remaining 44 patients. There were 26 (59.1 %) females and 18 (40.9 %) males in the study, aged from 24 to 66 years. The time between the two visits ranged from 6.0 to 24.7 months. Patient demographics are shown in Table 1. The LYGB surgeries were performed by the same team. No adverse event attributable to the LYGB surgery was recorded.

In this follow-up study of 44 OSA patients with obesity and T2DM, the total cured ratio and improved ratio of OSA after LYGB surgery were 63.6 and 79.5 %. The cured ratios after surgery in those with mild, moderate, and severe OSA at baseline were 77.3, 55.6, and 46.2 %, respectively. The corresponding improved ratios were 77.3, 77.8, and 84.6 %, respectively. These results indicate that LYGB surgery may be an effective treatment for OSA patients with obesity and T2DM.

Obesity is a known risk factor for the development of OSA [19]. Many studies have been performed to evaluate the effect of bariatric surgery in the treatment of OSA. However, although benefits of bariatric surgery in OSA have been reported, there is no recommendation for this procedure to be included in the clinical guidelines for the treatment of OSA, because studies in sufficiently diverse populations have not been conducted to date, and there is not yet enough evidence to recommend bariatric surgery for treating patients with both OSA and T2DM [20]. Thus, in our study, we focused on the effects of LYGB surgery in a Chinese obesity population with both OSA and T2DM; the outcomes supported the therapeutic efficacy of bariatric surgery in such patients, with 63.6 % of the OSA patients showing resolution and 79.5 % showing significant improvement, similar to a previous report [21]. Moreover, obese patients with severe OSA got more AHI reduction from weight loss than those with only mild or moderate disease (Table 3), consistent with Johansson et al. [22] and Foster et al. [23]. Additionally, the generated prediction model for postoperative AHI might provide a reference method for both surgeons and patients. The improved ratio showed a rising trend according to increasing AHI; however, the cured ratio showed a downward trend according to increasing AHI, probably because of a higher baseline value of AHI. The preoperative AHI value was lower in the cured group, while the mean change in AHI was similar between the two groups. This might mean that patients with less serious OSA have more chance to be cured. And, the similar change of AHI between the cured group and uncured group might be a comprehensive result, because higher AHI reduction happens with the increasing preoperative AHI, but the proportion of more serious OSA at baseline was lower in the cured group. In contrast, the preoperative AHI values were similar while the mean changes in AHI differed significantly between the improved and unimproved groups. Therefore, there might exist some factors, independent of the effect of LYGB surgery, which influence the severity of OSA. However, these contents were not taken into account in the present study.

Weight loss is accompanied by improvements in characteristics related not only to obesity but also to OSA, suggesting that weight loss may be a cornerstone of the treatment of both conditions [24]. However, a relationship between weight reduction and OSA remission has not been demonstrated previously. In our study, the change in AHI after bariatric surgery was correlated only with preoperative weight, AHI, WC, and IR index; no relationship was found between the change in AHI and the change in weight or BMI. In a randomized controlled study, John et al. reported that bariatric surgery did not result in a significantly greater reduction in AHI than conventional weight loss therapy, although the former did result in more weight loss [25]. They suggested that the state rather than the extent of weight loss was important in generating an altered neurohumoral and metabolic-inflammatory milieu, influencing defects in neuromuscular responses to mechanical loads [26, 27]. Furthermore, the modified gastrointestinal anatomy and physiology may influence the effect of bariatric surgery on OSA, although no evidence has been reported to date. Thus, the relationship between weight loss and OSA needs further investigation.

Several limitations of this study should be recognized. First, the duration of follow-up in our study was insufficient. Although a sustained effect of LYGB surgery on weight reduction and OSA improvement has been reported, more recent studies reported weight regain at 5 years after the operation in 50 % of patients [28], with therapeutic failure in 7–20 % at 8 years postoperatively [29]. Thus, modification of OSA through reduction in weight should be followed with a long-term plan. Second, we used data from our observational study, which might have been biased because it relied on patients volunteering for the second polysomnography test, although the preoperative data of the withdrawn group were not significantly different from those of the follow-up group. Third, our study could not provide information about the interaction between bariatric surgery and OSA, due to its simple design. Thus, the underlying mechanisms should be assessed in a future study.

Our findings indicate LYGB could result in stable and adequate weight loss for obesity patients with both OSA and T2DM, and also reinforce LYGB as an effective therapeutic intervention in the management of OSA in Chinese population. Additionally, the preoperative AHI and age might be important factors that influence the effort of LYGB. However, the underlying mechanisms require further study.

The authors would like to thank all the subjects who participated in the study. This study was supported by grants-in-aid from Shanghai shen-kang hospital management center project of Shanghai (SHDC12010209).