Obstructive Sleep Apnea: Evaluation of high risk individuals, knowledge and associated factors among a representative sample of Lebanese adults

Background : To date, there has been no large population-based study about Obstructive Sleep Apnea (OSA) in Lebanon. Our study evaluated high risk individuals, knowledge and associated factors of OSA among a representative sample of Lebanese adults. Methods: A cross-sectional study, conducted between June and August 2019, enrolled 472 people aged above 18. A proportionate random sample from all Lebanese Governorate was applied. Each governorate is divided into Caza (stratum), which in turn is divided into multiple villages. Two villages were selected randomly from the list of villages provided by the Central Agency of Statistics in Lebanon. Households were randomly selected from each village using an online software. Results: The percentage of physician-diagnosed sleep apnea in our sample was 11%; 159 (33.7%) had poor knowledge (scores ≤11), whereas 165 (35.0%) and 148 (31.4%) had moderate (scores between 12 and 15) and good (scores ≥16) knowledge respectively. The study results showed that -according to the Epworth Scale- having diabetes mellitus, myocardial infarction, arrhythmia, and hypertension were associated with higher daytime sleepiness. Furthermore, mild, moderate and severe excessive daytime sleepiness (EDS) percentages were 14.4%, 16.3% and 13.8% respectively. According to the STOP-BANG questionnaire, 31.6% of participants had an intermediate risk of OSA and 7.6% had a high risk. Diabetic patients and those with myocardial infarction were significantly associated with higher STOP BANG scores. Concerning knowledge, having heard about sleep apnea was associated with a higher knowledge score. Overall, 31.4% of the participants had a good score. SBQ showed that people suffering from DM had higher scores. A diabetic patient is more eligible to develop OSA. A high BMI, being a part of this scale, can be the cause. Obesity is a common factor of DM and OSA 47 , leading insulin resistance, decreased muscle activity, and chest compliance. The diabetic nephropathy can be manifested by HTN 48 . Diabetic patients have also defected microcirculation which might affect the pulmonary vasculature and lead to impaired oxygen exchange. Hypoxia and hypercapnia would stimulate the respiratory center and lead to arousal. knowledge scores in people who have heard about OSA, in comparison with those who have not heard about it. Same findings were shown after a survey carried out in Lorraine, in which people with this trait were more aware of OSA 23 . The survey results can be related to an easier access to information. Having heard about OSA from a family member, a neighbor or a friend would have increased people’s familiarity with this pathology and its associated symptoms. In fact, this would have pushed people to ask more about sleep apnea and its complications. These findings show the importance of patient educational programs to raise OSA awareness.

developing OSA with every 10% weight gain 11 . Other factors also associated with OSA include hypertension (HTN) 12 , smoking, and alcoholism 11 with a higher prevalence seen in those categories. Association of snoring with cardiovascular disease suggests that even a mild degree of SDB may have adverse health effects 13,14 .
Sleep deprivation influences the immune, endocrine, and nervous systems 15 . It leads to poor glycemic control 16 and influences body metabolism 17 .
Insightful that sleep plays a role in intellectual and academic attainments 18,19 , OSA has been involved with impaired daytime function and psychiatric symptoms 20 . It has a an impact on road safety and contributes to the burden of road-related morbidity and mortality 21 .
An awareness study done in Singapore showed a currently poor knowledge level among the general population 22 . Similar results were found in Lorraine-France as the complications and suggestive symptoms of OSA were still barely known 23 . In Riyadh, Primary Health Care physicians didn't completely recognize the importance and impact of OSA 24 .
Patients today need to be aware of common pathologies and symptoms that should lead them to seek a consultation. Several research studies have shown a positive relationship between OSA knowledge, and the application of preventive measures. Patient education improves treatment compliance 23 . SDB is highly prevalent with important public health outcomes. Individuals at high-risk of incidence of SDB should be identified so their treatment may be given a high priority.
To date, there has been no large population-based study associated with public awareness in Lebanon about sleep apnea. Besides, SDB prevalence is still unknown. A study conducted in Beirut reported that although 31% participants had a high risk of sleep apnea, only 5% were diagnosed by a physician, which makes OSA likely prevalent in Lebanon, but still underdiagnosed 25 . Conscious of the medical comorbidities associated with OSA and its socioeconomic disadvantages, we developed a study to evaluate high risk individuals, knowledge and associated factors in OSA among a representative sample of Lebanese adults.

Study and population
A cross-sectional study was conducted between June and August 2019, which enrolled people aged above 18 using a proportionate random sample from all Lebanese governorates (Beirut, Mount Lebanon, North, South, and Beqaa). Each governorate is divided into Caza (stratum), which in turn is divided into multiple villages. Two villages per casa were selected randomly from the list of villages provided by the Central Agency of Statistics in Lebanon. Households were randomly selected from each village using an online software (Research Randomizer) 26 . The interviews were conducted inside the household and all adults living there were eligible to participate. Excluded were people unable to understand Arabic (n=1) -the national language-and people with cognitive impairment (n=5) (trouble remembering or concentrating) 27 as reported by a family member.

Sample size calculation
According to the Epi info, sample size calculations assuming a 31% frequency of OSA among the general population in the absence of similar studies in the country, a 95% confidence level, a power of 80%, and a sample of 329 contestants was required to fulfill the objectives and allow for adequate power for bivariate and multivariable analyses. We conducted the questionnaire on a total of 600 individuals. Eighty-seven were excluded from the study (14.5%), eighty-one refused to participate, one was unable to understand Arabic and five people had cognitive impairment; twelve terminated the interview before completion (2%). A total of 472 (83.5%) completed the interview and was included in the final analysis.

Data collection
A standardized method of a face-to-face interview was adopted by a trained and study-independent personnel. The questionnaire was divided into four parts: The first part (Part 1: Socio-demographic characteristics) was collected through a multiple-choice format of 19 questions. The gender, the age, the weight, the height, the educational level (low (illiterate/primary), intermediate (complementary/ secondary) or high (university level) and the health insurance were mentioned. The governorate and the lifestyle (smoking, alcohol and coffee consumption) were also included, in addition to the number of traffic accidents per year. The monthly income was divided into 4 categories, as follows, based on the salary: none, low (<1000 USD), intermediate (1000-2000 USD), and high (>2000 USD). We asked about the last medical visit and its yearly frequency. The BMI was calculated from the measured weight and height of the individual.
The second part (Part 2: Personal diseases) evaluated whether the respondent had ever heard about OSA and if he/she had a prior physician diagnosis of OSA. If yes, the respondent was asked if he/she was currently on any sort of treatment. Questions about the history of personal diseases included HTN, diabetes (DM), cerebrovascular accident (CVA), arrhythmia, and myocardial infarction (MI). Nocturia was also mentioned, by citing the number of times a participant gets out of bed, at night, to urinate.
The third part (Part 3: The Knowledge Scale) intended to get information concerning the knowledge of OSA, subdivided into two main focuses: suggestive characteristics and possible complications. There were 13 items concerning suggestive OSA symptoms and characteristics (10 correct, plus 3 distractors) and 13 possible complications (7 correct, plus 6 distractors), as mentioned in the Appendix1. This yielded an overall score ranging between 0 and 26.
Currently, the Obstructive Sleep Apnea and Attitudes Questionnaire (OSAKA) is a valid tool to assess OSA knowledge among physicians 28 . However, few scales consisted of questions addressed to the general population 22,23 . To collect data related to knowledge and to investigate disease-related beliefs among the general population, we used a questionnaire based on the previously published "Guidelines for clinical practice in OSAHS in adults" 29 . It has been translated from the Loraine's questionnaire 23 into Arabic. Forward and back method was adopted for the translation from French to Arabic then from Arabic to French by two different translators. The two French versions were compared; discrepancies were resolved by consensus between the authors and the translators.
We considered the following answers as acceptable for the symptoms and characteristics: Snoring, respiratory breaks, daytime fatigue, night suffocating sensation, non-restorative sleep, daytime somnolence, concentration disorder, morning headache, nocturia, and obesity. For health consequences, those were the right answers: stoke, DM, HTN, dementia, cardiac arrythmia, MI, and road accidents. Score details are mentioned in the Appendix2.
The fourth part (Part 4: Screening): A thorough literature review highlighted the presence of well-validated scales used in research studies to diagnose OSA: the Epworth Sleepiness Scale (ESS) 30 and the STOP-BANG questionnaire (SBQ) 31 . These two scales were chosen since the ESS is recommended to be included in screening evaluations 32,33 , and the SBQ for being superior in detecting OSA in the general population 34,35 .
ESS inquires about falling asleep in some circumstances, presenting a subjective measure of daytime sleepiness. A scale of 0-3 (0 means "would never doze" and 3 means "high chance of dozing"). The total score ranges between 0 and 24. Higher scores indicate more daytime sleepiness; the cutoff for normal daytime sleepiness is 10 30 . The Arabic form has been validated as an authentic tool 36 . The SBQ, also valid in Arabic, included the STOP questions: Snoring behavior, Tiredness, Obstruction (gasping) and Pressure (hypertension). From the BANG questions we included the Neck circumference 37 . BMI, Age, and Gender were included in the score based on previous answers to avoid repetition and redundancy. It is scaled as low, intermediate and high OSA Risk based on the number of positive answers 31 -Appendix3-.
A pilot study was run on about 20 subjects -not included in the study-to ensure the understanding and acceptability of the questions in the general population. Few linguistic modifications improved the response rate in the final questionnaire.

Statistical analysis
Statistical Package for Social Science (SPSS) version 23 was used for the statistical analyses. Descriptive statistics were presented using mean and standard deviation for continuous measures, frequencies, and percentages for categorical variables.
The Student t-test and ANOVA test were used to assess the association between each continuous independent variable (ESS total score, SBQ total score, and knowledge score) and the sociodemographic and other variables. To calculate the p-value of the statistical significance, the Bonferroni correction compensates for that increase by testing each hypothesis at a significance level of α/m, where α is the desired overall alpha level and m is the number of hypotheses/tests conducted (23). Concerning the different scores, we tested 19 hypotheses/variables in each model, with a desired error α of 0.05; therefore, the Bonferroni correction would test each hypothesis at a p-value of 0.05/19=0.002.
Multivariable linear regression models were done to explore factors associated with the three scores as dependent variables and taking all variables that showed a p≤0.002 in the bivariate analysis as independent variables. A p<0.05 in the multivariable model was considered significant. Moreover, Cronbach's alpha was recorded for reliability analysis for each scale.

Results
The mean age of the participants was 39.39 ± 15.89. 51.7% of the respondents were men. Other descriptive results of our sample are summarized in Table 1. The percentage of physician-diagnosed sleep apnea in our sample was 11% [95% CI 0.082-0.138] (52 participants). The Cronbach's alpha values of the scales used were as follows: 0.833 for the Knowledge and 0.761 for the ESS.

Bivariate analysis
A significantly higher mean Epworth score was found in those with a low level of education compared to the other categories, in those who have a BMI of 30 or higher, in those who smoke 20 cigarettes or more per day, in those who were diagnosed with HT, DM, CVA, arrhythmia, and MI compared to those who were not.
A notably higher mean SBQ score was found in those with a low level of education compared to the other categories, in those living in Beqaa compared to the other regions, in those who were diagnosed with HT, DM, CVA, and MI compared to those who were not and in those who have previously heard about sleep apnea compared to those who have not.
A remarkably higher mean knowledge score was found in those living in Mount Lebanon compared to all other regions and in those who have previously heard about sleep apnea compared to those who have not (Table 2). Furthermore, higher age was significantly correlated with higher ESS total score (r=0.172; p<0.001).

Multivariable analysis
The results of a first linear regression, taking the ESS as the dependent variable, showed that having DM (B=2.21), MI (B=2.18), arrhythmia (B=1.73) and HTN (B=1.46) compared to the absence of those diseases were significantly associated with higher ESS total scores. (Table 3, Model 1).
The results of a second linear regression, taking the SBQ score as the dependent variable, showed that having DM (B=0.49) and MI (B=0.70) were significantly associated with higher SBQ scores (Table 3, Model 2).
The results of a third linear regression, taking the knowledge score as the dependent variable, showed that having heard about sleep apnea compared to those who have not (B=3.33) was significantly associated with higher knowledge scores (Table 3, Model 3).

Discussion
To the best of our knowledge, this study is the first large scale survey to assess high risk individuals for OSA among the general Lebanese population. In this representative sample of people aged above 18, 11% had already been diagnosed by a health care provider with OSA. Furthermore, according to the EES, mild, moderate, and severe EDS percentages were respectively 14.4%, 16.3% and 13.8%, whereas 31.6% had intermediate risk of occurrence of OSA according to the SBQ and 7.6% had high risk.
Multiple studies conducted worldwide have aimed to evaluate the prevalence of OSA. The proportion of Lebanese participants screening positive for OSA on the questionnaire is in harmony with the worldwide and regional estimated prevalence. It ranges from 9% to 38% in community-screened populations. An American study, published this year, estimated a prevalence of moderate to severe OSA of 37.0% 38 .
This prevalence strongly increased during the last 20 years, depending on age, gender and, BMI 39 . The mean age of the respondents was 40 years (± 15.89). A significantly higher prevalence is seen in older groups. It affects 88% of men and 66% of women aged between 65 and 69 8 .
Middle aged Lebanese people at risk for OSA might have other comorbidities.
This study was also able to shed light on some factors associated with EDS.
Having DM was significantly associated with higher daytime sleepiness according to the ESS. Mechanisms may include autonomic dysfunction and loss of upper airway innervations increasing apnea/hypopnea over time 40 . Thus hypercapnic stimulus might lead to awakening and poor sleep quality, resulting in daytime doziness. On the other side, intermittent chronic hypoxia would alter the metabolism and the daily activity promoting insulin resistance.
Having arrhythmia and MI were both associated with EDS. The Journal of the American Heart Association investigated EDS as a poor prognostic factor post MI 41 . MI risk factors are known: obesity, DM, smoking, etc. 42 .
A sedentary lifestyle is a shared risk factor for cardiovascular disease and to sleep disorders 43 . Laziness due to lack of sleep would induce cardiovascular diseases or contribute to their aggravation.
Also, OSA appears to play an important role in the recurrence of Atrial Fibrillation (AF), but its independent role in the incidence of new onset AF remains unclear 42 . This might be due to the activation of the nervous system. Repeated arousals from sleep would stimulate the sympathetic nervous system and hence cardioacceleration 44 . This would first cause tiredness and increase daytime sleepiness.
A higher daytime sleepiness score was seen in hypertensive people 45 . The journal of the American Society of HTN studied "the influence of hypertension on daytime sleepiness in obstructive sleep apnea" and showed that HTN decreased sleep efficiency. Even with lower ESS scores compared to normotensives, people with HTN must undergo further assessments 46 . In hypoxic situations, the body may increase blood flow to main organs, causing chronic damage to the vessels and the neurologic system. The accommodation to hypoxic situations may be the cause of higher blood pressure.
Sympathetic cardiac tone and pulmonary dilatation may increase oxygen needs and induce frequent arousals. Daytime sleepiness would likely try to compensate the sleep deprivation.
A resistant HTN, chronic fatigue, and headache might be simple alarming signs to screen for OSA.
The SBQ showed that people suffering from DM had higher scores. A diabetic patient is more eligible to develop OSA. A high BMI, being a part of this scale, can be the cause. Obesity is a common factor of DM and OSA 47 , leading insulin resistance, decreased muscle activity, and chest compliance. The diabetic nephropathy can be manifested by HTN 48 . Diabetic patients have also defected microcirculation which might affect the pulmonary vasculature and lead to impaired oxygen exchange. Hypoxia and hypercapnia would stimulate the respiratory center and lead to arousal.
Having MI was associated with a higher SBQ score. A systematic literature review proved an association between OSA and cardiovascular events 49 . In fact to 65% of patients who suffer from cardiovascular diseases are diagnosed with OSA 50 . A low cardiac output following a MI would cause arterial hypoxia 49 . This would influence small pulmonary vasculature and airways diffusion capacity.
People who suffered from a MI might have lost the integrity of their vasculature. A lower cardiac output would affect the pulmonary circulation and damage the gas exchange barrier. On the other side, a good coronary oxygenation would prevent cardiac events 1 .
Our study provided data of present OSA awareness level in Lebanon. The results showed that the Lebanese population was not properly aware of this disease. Only 31.4% of the participants had good OSA knowledge. Characteristics, symptoms, and complications of OSA were barely known. The studies conducted in France and Singapore -also aiming to evaluate the knowledge of OSA among the population-showed that about 2/3 of the participants were familiar with some symptoms. Though, there was a lack of knowledge regarding OSA complications 22,23 . People might tend to give more importance to other common pathologies. The more people are diagnosed early with OSA, the more likely it is they share their experience with others. Moreover, "sleep disorders" is somehow an embarrassing topic that people avoid to discuss.
Previous studies insisted on the need for further education 22,23,51,52,53,54 . This helps increase awareness and promotes early OSA detection thus decreasing comorbid health risks.
Moreover, the results showed higher knowledge scores in people who have heard about OSA, in comparison with those who have not heard about it. Same findings were shown after a survey carried out in Lorraine, in which people with this trait were more aware of OSA 23 . The survey results can be related to an easier access to information. Having heard about OSA from a family member, a neighbor or a friend would have increased people's familiarity with this pathology and its associated symptoms. In fact, this would have pushed people to ask more about sleep apnea and its complications.
These findings show the importance of patient educational programs to raise OSA awareness.

Limitations
This cross-sectional research project has multiple limitations. Since it's a single point in time measurement, it cannot infer a causality relationship. The major respondents were form North Lebanon, so the sample being studied may not be representative of the whole population. In addition to that, relying on closed-ended questions may have limited the amount of information received The monthly individual income was included in the collected data but the household-equivalent income could not be calculated. This could lead to over or under evaluated symptoms and characteristics. Moreover, investigators were available for any clarifications if needed. However, social bias should be minimal as the anonymity was assured. Individuals may have chosen to misrepresent self-reported behaviors and pick a more socially acceptable answer to avoid negative judgment.
Furthermore, the Arabic translation of the existing questionnaire 23 was not specifically validated in Lebanon. Despite those limitations, we believe that the data found in this study will be useful in future surveys to examine trends of OSA awareness.

Conclusion
The actual study proves that EDS, having adverse health effects, is associated with multiple morbidities. Besides, the general Lebanese population isn't aware enough of this disease. Comparing the rate of high risk individuals to the physician-diagnosed ones, we conclude that in Lebanon, OSA is likely prevalent but underdiagnosed. Ongoing health campaigns and screenings should be assigned to target the general community. People today need to be reasonably aware of common pathologies and the associated symptoms that should lead them to seek a consultation. Accordingly, future research is needed to assess primary health care providers' knowledge. Physicians should carry the responsibility for providing adequate screening and diagnosis.

Declarations Ethics Approval and Consent to Participate
The study protocol was approved by the Holy Spirit University of Kaslik (USEK) ethics committee. A written informed consent was obtained from each participant.

Consent for publication
Not applicable.

Availability of data and materials
All data generated or analyzed during this study are not publicly available to maintain the privacy of the individuals' identities. The dataset supporting the conclusions is available upon request to the corresponding author.

Competing interests
The authors have nothing to disclose.

Funding
None.

Author contributions
AC and DM were responsible for the data collection and design of the study; AC drafted the manuscript; SH carried out the analysis and interpreted the results, assisted in drafting and reviewing the manuscript; ED was the project supervisor. All authors reviewed the final manuscript and gave their consent.

Acknowledgments
We express our gratitude to the participants who donated their time in completing the questionnaires. We would also like to thank the research assistants and the investigators who contributed in the data collection, and the staff experts who helped building this study. OSA=Obstructive sleep apnea

Supplementary Files
This is a list of supplementary files associated with this preprint. Click to download. Appendix1.pdf