Impact of Laparoscopic Sleeve Gastrectomy on Obstructive Sleep Apnea Symptoms Based on the STOP-BANG Questionnaire: A Prospective Study

Abstract

Aim:

To evaluate the impact of weight reduction after laparoscopic sleeve gastrectomy (LSG) on obstructive sleep apnea (OSA) symptoms based on the STOP-BANG questionnaire (SBQ).

Methods:

This prospective study included patients older than 18 years, with OSA, and who had planned to undergo LSG surgery. A comparison between preoperative and postoperative scores of the SBQ was performed for all patients.

Results:

The study included 82 obese patients (53 females and 29 males) with a mean age of 30.5 ± 8.8 years. The SBQ scores of the patients showed significant decrease postoperatively (2.15 ± 1.32) compared to the preoperative scores (3.78 ± 1.55). Furthermore, the number of patients who were using continuous positive airway pressure (CPAP) was significantly reduced from 14 patients preoperatively to only 4 patients postoperatively (p = 0.002). All components of SBQ score showed postoperative improvement, especially (do you snore loudly?), (do you often feel tired, fatigued, or sleepy during daytime?), and (body mass index more than 35?), which showed significant improvements.

Conclusions:

Weight reduction after LSG resulted in a significant improvement of OSA, as shown by SBQ scores. SBQ is a simple and easy tool to assess the symptoms of OSA and could be used successfully for follow-up of OSA symptoms.

Introduction

In Obstructive sleep apnea (OSA), breathing stops involuntarily for brief periods of time during sleep. It is associated with major comorbidities, such as excessive daytime sleepiness and decreased cognitive performance.^1,2

The underlying pathophysiology of OSA is multifactorial and may vary considerably between individuals.³ The most commonly listed risk factors were obesity and upper airway narrowing secondary to craniofacial and soft tissue abnormalities.⁴

OSA is generally underdiagnosed worldwide and up to 82% of men and 93% of women with OSA remain undiagnosed.⁵ Untreated OSA is associated with decreased quality-of-life scores and adverse health consequences.⁶ These include cardiovascular diseases, diabetes, depression, anxiety, decreased intellectual functioning, and increased risk of road traffic accidents.^7,8 It also poses significant economic burden on the individuals as well as the health care system.⁹

The gold standard for diagnosis of OSA is the full-night polysomnography performed at the sleep laboratory. Due to the high expense and time-consuming nature of this procedure, other screening tools were developed to detect high OSA risk. These could reserve the use of sleep studies for selected cases.¹⁰ The STOP-BANG questionnaire (SBQ) is significantly less complex to score than other screening tools such as the Strengths and Difficulties Questionnaire (SDQ), Berlin Questionnaire, and the American Society of Anesthesiologists (ASA) Checklist. In contrast to the ASA checklist, SBQ does not require airway evaluation by health care staff.¹¹ It was reported that the SBQ has the best performance in OSA screening.¹²

Obesity is considered a worldwide pandemic that has global implications for health and disease.¹³ It was clearly reported that obesity predisposes to and potentiates OSA.¹⁴ The prevalence of OSA and its consequences are likely to increase in light of the current obesity pandemic.^14,15

Many treatment modalities were described for the management of obesity; however, bariatric surgery is considered the only therapeutic approach associated with significant, quick, and constant weight loss outcome.¹⁶ In addition, laparoscopic sleeve gastrectomy (LSG) has been considered the primary bariatric procedure.¹⁷ This may be attributed to its effectiveness in achieving weight reduction with lower rate of complications compared to other bariatric surgical modalities.¹⁸

Continuous positive airway pressure (CPAP) is the first line of treatment in OSA, but the adherence rate of CPAP is problematic.¹⁹ Weight reduction, oral appliance therapy, and correctional surgery for anatomic obstructions can also be suggested, but there is still no sufficient evidence to support these as therapeutic modalities.²⁰ Some studies reported positive effects of bariatric surgery on sleep parameters and symptoms in obese patients with OSA, which can result in remission in many patients.^21,22

Therefore, the aim of our study was to evaluate the impact of weight reduction after LSG on OSA symptoms based on the SBQ.

Patients and Methods

This study followed a prospective research design. It was conducted in the Bariatric Unit, Aseer Central Hospital, Abha city, Saudi Arabia, from January 2020 to December 2020.

Eligibility criteria

All patients older than 18 years, diagnosed with OSA, and had planned to undergo LSG surgery. All patients had failed supervised weight reduction programs (including diet and exercise) for at least 1 year.

Exclusion criteria included patients younger than 18 years and patients who had no OSA preoperatively and who were diagnosed preoperatively with OSA due to any other disorder rather than obesity and required specific management.

The minimal sample size for the study was calculated according to Epitools application²³ to be 73, based on an expected prevalence of OSA in the Saudi population of about 5.5%,²⁴ and a relative risk of 4 among obese subjects,²⁵ a 95% confidence level, and 80% power.

Preoperative workup

All patients were subjected to thorough history taking and physical examination. Their weight and height were measured, and the body mass index (BMI) was calculated for each patient (kg/m²). The patients were graded according to their BMI into severely obese (BMI, 35–39.9 kg/m²), and morbidly obese (BMI, 40–49.9 kg/m²). Patients were subjected to all preoperative routine investigations. All patients were evaluated in the outpatient clinic of the Otorhinolaryngology Department, where detailed history and examination were done. In addition, all required investigations, including polysomnography, were performed to diagnose OSA. Patients with OSA were asked to fill the SBQ before undergoing surgery.

This questionnaire consists of four questions in reference to the mnemonic (STOP), incidence of Snoring, Tiredness during daytime, Observed apnea, and high blood Pressure; and another four indices in reference to the mnemonic (BANG): Body mass index >35 kg/m², Age >50 years, Neck circumference >40 cm, and male Gender.²⁶ Patients with SBQ score from 0 to 2 were considered to have mild OSA and from 3 to 4 were considered to have intermediate OSA, while patients who had scores ≥5 were considered to have severe OSA.^11,27

A written informed consent was taken from all patients for the operation as well as participation in the research.

Operative workup

All patients underwent LSG by the same team of bariatric consultants who were experts in the field of LSG.

Postoperative workup

All patients were kept in the ICU overnight during the postoperative period.

Patients followed the hospital protocol regarding feeding and medications. Patients were discharged on the first postoperative day unless complications were anticipated.

Follow-up

Patients had their first follow-up postoperative visit 2 weeks after the operation, during which wound care was performed. Then, patients were seen after 3, 6, and 12 months to follow their BMI. In addition, patients filled the SBQ at 12 months postoperatively.

Outcomes

Primary endpoint

To detect the effects of weight reduction after LSG on OSA symptoms by comparing preoperative to postoperative SBQ scores.

Secondary endpoint

To detect the effects of weight reduction after LSG on each component of SBQ at 12 postoperative months.

Statistical analysis

Data processing was done using the Statistical Package for Social Sciences (IBM SPSS version 25; SPSS, Chicago, IL). Descriptive statistics were applied (frequency and percentage for categorical variables, in addition to mean and standard deviation for quantitative variables). Paired t-test and χ² test (e.g., McNemar test) were applied to compare preoperative with postoperative patients' data. A statistically significant difference was considered at p-values <0.05.

Ethical approval

The research protocol was approved (ECM#2020-208) by the Research Ethics Committee at King Khalid University (HAPO-06-B-001), Saudi Arabia. All collected data were dealt with confidentially and all measures were taken to guarantee anonymity of participant patients.

All procedures performed in this study were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Results

The study included 82 patients (53 females and 29 males) who fulfilled the inclusion criteria. The age of patients ranged from 18 to 58 years with a mean of 30.5 ± 8.8 years. Most of our patients (68.3%) were morbidly obese and only 8.5% were smokers. Preoperative demographic and clinical characteristics of the patients are shown in Table 1.

Table 1.

Demographic and Clinical Characteristics of the Patients

	Studied group (N = 82)	%
Age groups
<30 Years	51	62.2
30–45 Years	26	31.7
>45 Years	5	6.1
Gender
Male	29	35.4
Female	53	64.6
Smoking status
Smoker	7	8.5
Nonsmoker	68	82.9
Ex-smoker	7	8.5
BMI (kg/m²)
35 to <40	26	19.5
≥40	56	68.3

BMI, body mass index.

The STOP-BANG scores of patients showed significant decrease postoperatively compared to the preoperative scores. Furthermore, symptoms of sleep apnea (based on STOP-BANG scores) showed significant improvement after LSG. The number of patients who were using CPAP was significantly reduced from 14 patients preoperatively to only 4 patients postoperatively. The comparison between preoperative and postoperative status of sleep apnea based on STOP-BANG score is shown in Table 2.

Table 2.

Comparison Between Preoperative and Postoperative Status of Sleep Apnea Based on STOP-BANG Score

	Preoperative status	Postoperative status	p
STOP-BANG score (mean ± SD)	3.78 ± 1.55	2.15 ± 1.325	<0.001^a
Severity of the sleep apnea based on STOP-BANG score, n (%)
Low	46 (56.1)	62 (75.6)
Intermediate	27 (32.9)	15 (18.3)
High	9 (11.0)	5 (6.1)	<0.001^a
Patients using (CPAP therapy), n (%)
Yes	14 (17.1)	4 (4.9)
No	68 (82.9)	78 (95.1)	0.002^a

p < 0.05 is significant.

CPAP, continuous positive airway pressure; SD, standard deviation.

Analysis of components of STOP-BANG score revealed variable changes. Some components of the questionnaire had significant improvement postoperatively (Do you Snore loudly?), (Do you often feel Tired, fatigued, or sleepy during daytime?), and (BMI more than 35?). Nevertheless, some components showed nonsignificant postoperative improvement (Has anyone Observed you stop breathing during your sleep?), (Do you have, or are you being treated for, high blood pressure?), and (Neck circumference greater than 17″—male or 16″—female?). In two components, the comparison between preoperative and postoperative data was not applicable, that is, (Age—Over 50 years old?) and (Gender—Male?). The impact of LSG on the different components of the STOP-BANG score is shown in Table 3.

Table 3.

The Impact of laparoscopic Sleeve Gastrectomy on the Different Components of the STOP-BANG Score

	Preoperative		Postoperative
	No.	%	No.	%	p
Do you Snore loudly?(Louder than talking or loud enough to be heard through closed doors)	25	30.5	6	7.3	<0.001^a
Do you often feel Tired, fatigued, or sleepy during daytime?	62	75.6	45	54.9	0.008^a
Has anyone Observed you stop breathing during your sleep?	12	14.6	10	12.2	0.819
Do you have, or are you being treated for, high blood pressure?	8	9.8	4	4.9	0.369
BMI more than 35?	82	100.0	60	73.2	<0.001^a
Age—over 50 years old?	—	—	—	—	—
Neck circumference greater than (17″—male) or (16″—female)?	18	22.0	15	18.3	0.679
Gender—male?	—	—	—	—	—

p < 0.05 is significant.

After 12 months, the mean BMI improvement was 9.3 ± 2.8 kg/m², while the mean STOP-BANG score improvement was 1.4 ± 0.5. There was a significant positive correlation between BMI and STOP-BANG improvements (r = +0.674, p < 0.001). No predictor or parameter could be found to be associated with a better improvement of STOP-BANG score in our study. Furthermore, there was a positive significant correlation between the severity of OSA based on the SBQ and Apnea Hypopnea Index (AHI). The correlation is shown in Table 4.

Table 4.

Correlation Between the Severity of Obstructive Sleep Apnea Based on the STOP-BANG Questionnaire and Apnea Hypopnea Index

Preoperative	Preoperative AHI
STOP-Bang	Mild		Moderate		Severe		Total		p
grades	No.	%	No.	%	No.	%	No.	%
Low	2	4.3	44	95.7	0	0.0	46	56.1
Moderate	0	0.0	27	100.0	0	0.0	27	32.9
High	0	0.0	5	55.6	4	44.4	9	11.0
Total	2	2.4	76	92.7	4	4.9	82	100.0	<0.001^a

p < 0.05 is significant.

AHI, Apnea Hypopnea Index.

Discussion

There are growing data regarding the relationship between obesity and OSA. Nowadays, obesity is considered a major risk factor for the development and progression of OSA.^13,14,21,22 The prevalence of OSA is nearly twice among obese or severely obese patients compared to normal-weight adults. Furthermore, patients with mild OSA are at a sixfold increased risk of progression of OSA if they gain 10% of their baseline weight.²⁸

The relationship between obesity and OSA may be complicated and not fully understood. Surprisingly, children and adolescents with OSA were found to have more than sixfold increased risk of having metabolic syndrome compared to those without OSA.²⁹ This raises the importance of screening and accurate diagnosis of OSA even as early as in childhood.

In this study, all patients were already diagnosed with OSA. We used the SBQ to assess the severity of the symptoms. Although STOP-Bang is well known as a screening test, Filograna-Pignatelli et al³⁰ reported that the SBQ identifies patients with OSA and daytime sleepiness. Its simplicity of the answers makes it a suitable tool for both screening centers and the General Practitioner's Clinic. In our study, there was a positive significant correlation between the severity of OSA based on the SBQ and AHI. In agreement with our findings, Oshita et al³¹ and Pes et al³² reported that the STOP-BANG score correlates with AHI and is useful for predicting OSA severity. Based on the difficulty, nonavailability, and complexity of polysomnography, we suggest that polysomnography can be performed for patients with high STOP-Bang scores.

Assessing the responses and the rate of completion of the SBQ in this study revealed high rate of completion (100%) and easy understanding of questions by all participating patients. We agree with Chung et al, who reported that SBQ can be completed quickly and easily with very high overall response rates (90–100%).³³

In this study, we used the cutoff score of ≥3 to diagnose intermediate to severe OSA. Most studies used the same cutoff score.^11,27,31,33 The sensitivity of the questionnaire was found to be high using a cutoff score of ≥3: 84% in detecting any sleep apnea (AHI >5 events/h), 93% in detecting moderate to severe sleep apnea (AHI >15 events/h), and 100% in detecting severe sleep apnea (AHI >30 events/h), and corresponding specificities were 56.4%, 43%, and 37%.²⁷ If patients score 0–2 on the SBQ, they are considered to be at low risk of OSA, and the possibility of those patients having moderate to severe sleep apnea can be confidently ruled out.¹¹

Although SBQ scores ≥3 are very sensitive (sensitivity range, 91–100%) to detect OSA in obese and morbidly obese patients, this is associated with low specificity (from 7% to 28%), yielding high false positive rates. A SBQ score cutoff of 4 was shown to provide a better balance of sensitivity and specificity in the obese population. In morbidly obese patients, an SBQ score ≥4 retained high sensitivity across the entire spectrum of OSA severity, with a sensitivity of 90% for detecting severe OSA, whereas an SBQ score ≥6 demonstrated a specificity of 81% for detecting severe OSA.³⁴

Unfortunately, we did not include controls (those who do not have OSA) or false positives in the study. Therefore, we could not calculate the exact sensitivity and specificity of STOP-Bang. More studies may be required to determine the best cutoff score for SBQ to achieve the best combination of sensitivity and specificity, especially among obese patients.

In this study, our patients' SBQ scores showed significant decrease after LSG compared to the preoperative scores with significant reduction of patients who were using CPAP from 14 patients preoperatively to only 4 patients postoperatively. Similar to our results, Sillo et al³⁵ reported significant improvements in OSA after bariatric surgery, with 55.3% of patients demonstrating significant improvement or resolution using objective criteria. Although average preoperative AHI readings while on CPAP were already below 10 events per hour (due to effective CPAP therapy), there were statistically significant decreases in AHI postoperatively.

Based on these results, 30% of patients were successfully weaned off CPAP. Ravesloot et al³⁶ clearly demonstrated significant improvement and even remission of OSA following bariatric surgery in obese patients, as measured by polysomnography. They reported that bariatric surgery initiates dramatic improvement of clinical and sleep parameters during the first 7 months, which continues at a slower rate over the next 10 months.

Sarkhosh et al,³⁷ in a systematic review that included 69 studies with 13,900 patients who underwent Roux-en-Y gastric bypass, LSG, or biliopancreatic diversion (BPD), reported that all the procedures achieved profound effects on OSA, as over 75% of patients saw at least an improvement in their sleep apnea. BPD was the most successful procedure in improving or resolving OSA, with laparoscopic adjustable gastric banding being the least. They concluded that, bariatric surgery is a definitive treatment for OSA, regardless of the specific type.

In our study, we found that almost all components of SBQ were improved after surgery, especially loud snoring and daytime fatigue and sleepiness. There are well-documented health risks associated with snoring like poor sleep quality, OSA, heart abnormalities, and headache.^38,39 In addition, patients with OSA usually have daily fatigue, which can be easily neglected because of the underdiagnosis of the OSA and the lack of research to understand these patients.⁴⁰

Continuously untreated fatigue leads to energy depletion, reduced motivation, and lack of concentration, and may end up with bad influences on the individual's psychological well-being, and disables their daily functioning.⁴¹ Post-LSG weight reduction could solve the problems of snoring and daily fatigue as demonstrated by the analysis of the SBQ components in this study. This may have a positive effect on the patient's quality of life. Furthermore, the easy application of SBQ may facilitate its use to detect OSA as early as possible to avoid its preventable consequences.

Nevertheless, using SBQ to follow up OSA and to assess the improvement of its symptoms requires some modifications to avoid the nonapplicability of some of its components, such as gender and age in most patients. Further studies may be necessary to properly address this issue.

Limitations

Being a single-center study may be the limitation of this research.

Conclusions

Weight reduction after LSG is associated with a significant improvement of OSA as shown by SBQ scores. SBQ is a simple and easy tool to assess the symptoms of OSA. It can be used successfully for follow up of OSA symptoms. However, some modifications of the SBQ may be required to avoid the nonapplicability of the gender and age components.

Footnotes

Disclosure Statement

All authors declare no conflict of interests.

Funding Information

The study was self-funded.

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