Obstructive Sleep Apnea among the Lebanese general population: Prevalence, associated factors and knowledge

Background : To date, there has been no large population-based study associated with public awareness in Lebanon about sleep apnea. Our study investigated the prevalence of, associated factors and knowledge of Obstructive Sleep Apnea (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 years. A proportionate random sample from all Lebanese Mohafazat was applied. Results: The study results showed that a higher number of cigarettes per day, having diabetes mellitus, myocardial infarction, hypertension and arrhythmia were associated with higher daytime sleepiness. Participants living in the North had less daytime sleepiness, whereas those living in Beqaa had higher daytime sleepiness compared to those living in Beirut. Concerning knowledge, having heard about sleep apnea and having a university level of education were associated with a higher score, whereas having cerebrovascular accidents was associated with lower knowledge scores. Conclusion Complications of OSA are still poorly known, as are certain suggestive symptoms. Given the local relevance of OSA, ongoing health campaigns and innovative educational programs should be assigned to target the general community. Our results showed that a higher number of cigarettes smoked per day was significantly associated with higher daytime sleepiness, in agreement with previous studies 52,53 . While the association between cigarette smoking and OSA is plausible, the evidence is less than conclusive 54 . Cigarette smoking may worsen swelling and inflammation in the upper airway, affecting the neuromuscular function, and making snoring worse 55 . It may increase the severity of OSA through arousal mechanisms and trouble sleep architecture 56 . It has been hypothesized that each of these conditions adversely affects the other, leading to increased morbidity 52 .

estimated prevalence of OSA ranges from 9% to 38% 8 in community-screened populations to a significantly higher prevalence in those older than 60 years 9 . In the middle-to older-aged general population, it affects 49% of men and 23% of women 10 . Based on socio-demographic studies, men are three times more likely than women to have OSA 9 .
It is well known that OSA is tightly linked to multifactorial etiologies and physical attributes such as oropharyngeal narrowed airway, neck and waist circumference 11 , body mass index (BMI) and obesity 9 . In fact, the Wisconsin Sleep Cohort proved a 32% rise in Apnea-hypopnea index (AHI) and a six-fold increased risk of developing OSA with every 10% weight gain 12 . Other factors also associated with OSA include hypertension 13 , smoking and alcoholism 12 with a higher prevalence seen in those categories of people. Association of snoring with cardiovascular disease suggests that even a mild degree of sleep-disordered breathing may have adverse health effects 14,15 . Lack of sleep has an effect on the immune, endocrine and nervous systems 16 and is associated with poor glycemic control 17 . Afterwards, insufficient sleep is an influencer of body metabolism 18 .
Insightful that sleep plays a role in intellectual and academic attainments 19,20 , OSA has been involved with impaired daytime function and psychiatric symptom 21 . It has a relevant impact on road safety, as it substantially contributes to the burden of road-related morbidity and mortality 22 .
An awareness study done in Singapore showed a currently poor knowledge level among the general population 23 . Similar results were found in Lorraine-France as the complications and suggestive symptoms were still barely known 24 . In Riyadh, Primary Health Care physicians didn't completely recognize the importance and impact of Obstructive Sleep Apnea 25 .
Patients today need to be aware of common pathologies and symptoms that should lead them to consult. Several research studies have shown a positive relationship between obstructive sleep apnea knowledge, and application of preventive measures. Moreover, patient education improves treatment compliance 24 . Sleep-disordered breathing is highly prevalent, with important public health outcomes.
Individuals at high risk of incident SDB should be identified so treatment efforts can be focused on them.
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 were at high risk for sleep apnea, only 5% were diagnosed by a physician, which makes sleep apnea likely prevalent but underdiagnosed in Lebanon 26 . Conscious of the medical comorbidities associated to OSA, and its socioeconomic disadvantages, we developed a study to evaluate the prevalence of and factors associated with OSA and knowledge about it among a representative sample of Lebanese adults.

Study and population
A cross-sectional study was conducted between June and August 2019, which enrolled 500 people aged above 18 years 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 to multiple villages. Two villages 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 27 . Excluded were people unable to understand Arabic -the national language-people with cognitive impairment (trouble remembering or concentrating) 28 as reported by a family member, or who refused to participate in the survey.

Sample size calculation
According to the Epi info sample size calculations with a population size of 5 million in Lebanon, assuming a 50% frequency of OSA knowledge among the general population in the absence of similar studies in the country, a 95% confidence level, a power of 80%, and an acceptable bound of error of 5%, a sample of 384 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 refused to participate in the study (14.5%), and twelve terminated the interview before completion (2%). A total of 472 (83.5%) completed the interview and were included in the final analysis.

Data collection
A standardized method of interviewing was adopted by trained, study independent personnel. We used as our measurement tool a strictly anonymous questionnaire 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 (illiterate, primary, secondary, university level or higher education) 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 accident 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 last medical visit and its yearly frequency. The BMI was calculated from the reported weight and height of the individual.
The second part (Part 2: Personal diseases) asking whether the respondent had ever heard about OSA, 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 history of personal diseases included hypertension (HTA), diabetes (DM), cerebrovascular accident (CVA), arrhythmia and myocardial infarction (MI). Those where settled in a chronology compared with OSA diagnosis, if present: "yes, before OSA diagnosis" and "yes, after OSA diagnosis"; the other possible answers were "no" and "yes, without OSA diagnosis". 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 symptoms and possible complications. There were 13 items concerning suggestive OSA symptoms (10 correct, plus 3 distractors) and 13 possible complications (7 correct, plus 6 distractors), as mentioned in the Appendix1. This yielded an overall score ranged between 0 and 26.
Currently, the Obstructive Sleep Apnea and Attitudes Questionnaire (OSAKA) is valid for use in physicians to assess OSA knowledge 29 . However, few scales consisted of questions addressed to the general population 23,24 . 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" 30 . It has been translated from the Loraine's questionnaire 24 in Arabic. Forward and back method was adopted for the translation from French to Arabic then from Arabic to French by two different translators, the latter understanding of the content of the different scales. 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: Snoring, respiratory breaks, daytime fatigue, suffocating sensation, non-restorative sleep, daytime somnolence, concentration disorder, morning headache, nocturia and obesity. For health consequences, those were the right answers: stoke, DM, HTA, dementia, cardiac arrythmia, MI and road accident. To avoid the selection of a random answer by participants, the "I don't know" answer was added 24 in addition to the no and yes answers. One point was given for a "yes" answer, 0 for a "no" or "I don't know" answer. Although, for itchy at night, joint pain and vomiting in the morning, 1 point was given for a "no" answer and 0 for a "yes" or "I don't know" answer. Same for a "no" answer to: hair loss, depression, deafness, libido dysfunction, language disorder and respiratory failure, 1 point was given, and 0 points for "yes" or "I don't know" answers.  32 . These two scales were chosen since the ESS is recommended to be included in screening evaluations 33,34 , and the SBQ for being superior in detecting OSA in the general population 35,36 .
ESS inquires about falling asleep in some circumstances, referring to the usual way of life. The Arabic form has been validated as an authentic tool 37 . The SBQ, also valid in Arabic, reported snoring behavior, tiredness, gasping, hypertension and neck circumference 38 . It is scaled as "OSA-low Risk" for a positive answer to 0-2 questions, "OSA-Intermediate Risk" for 3-4 positive answers and "OSA-High Risk" for a score of 5-8, or a minimum of 2 on the STOP questions in addition to male gender, BMI>35kg/m 2 or an elevated neck circumference (>43cm in male or >41cm in woman) 32 .
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 (Epworth total score, Stop Bang 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 individual 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 knowledge, attitude and practice scores, we tested 19 hypotheses/variables in each model, with a desired error α of 0.05; therefore, the Bonferroni correction would test each individual 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% males). Other descriptive results of our sample are summarized in Table 1 Moreover, the mean knowledge score was 13.72 ± 3.86. When using the visual binning option in SPSS, the results showed that 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.

Bivariate analysis
A higher mean Epworth score was significantly found in males compared to females, in those with a high monthly income compared to all other categories, in those living in Beirut compared to other regions, in those who were diagnosed with hypertension after the OSA diagnosis compared to the other groups, in those diagnosed with diabetes mellitus, cerebrovascular accidents and myocardial infarction without OSA diagnosis compared to the other groups, in those diagnosed with arrhythmia before OSA diagnosis and in those who heard about sleep apnea compared to those who did not.
A higher mean Stop Bang score was significantly found in those living in Bekaa compared to the other regions, in those who were diagnosed with hypertension after sleep apnea diagnosis and in those diagnosed with myocardial infarction without sleep apnea diagnosis compared to the other categories.
A higher mean knowledge score was significantly found in those who did not smoke waterpipe compared to those who did, in those who had a university level of education compared to all other levels, in those living in Mount Lebanon compared to all other regions, in those who had social security and private insurance compared to the other groups, in those who had cerebrovascular accidents after sleep apnea diagnosis compared to the other groups and in those who heard about sleep apnea compared to those who did not. Post hoc analysis: Epworth score: monthly income (no vs high p = 0.011; low vs high p = 0.016); mohafaza (Beirut vs North p = 0.002); hypertension (no vs yes without sleep apnea diagnosis p < 0.001; no vs yes before sleep apnea diagnosis p = 0.016; no vs yes after sleep apnea diagnosis p = 0.005); diabetes mellitus (no vs yes without sleep apnea diagnosis p < 0.001); cerebrovascular accident (no vs yes without sleep apnea diagnosis p < 0.001); myocardial infarction (no vs yes without sleep apnea diagnosis p < 0.001); arrhythmia (no vs yes without sleep apnea diagnosis p < 0.001). Stop Bang score: Mohafaza (Beirut vs North p < 0.001; Mount Lebanon vs North p = 0.023; North vs South p = 0.027; Bekaa vs North p < 0.001); hypertension (no vs yes without sleep apnea diagnosis p < 0.001; no vs yes after sleep apnea diagnosis p = 0.005); diabetes mellitus (no vs yes without sleep apnea diagnosis p = 0.004); cerebrovascular accident (no vs yes after sleep apnea diagnosis p = 0.019); myocardial infarction (no vs yes without sleep apnea diagnosis p = 0.002). Knowledge score: education level (illiterate vs university p = 0.001; complementary vs university p < 0.001; secondary vs university p < 0.001); coffee drinking (none vs everyday p = 0.02); insurance coverage (no vs private p = 0.03; no vs social security and private p < 0.001; social security vs social security and private p = 0.001); cerebrovascular accident (no vs yes without sleep apnea diagnosis p = 0.004).
Furthermore, higher age (r = 0.172; p < 0.001), higher BMI (r = 0.214; p < 0.001) and a higher number of cigarettes per day (r = 0.119; p = 0.01) were weakly but significantly correlated with a higher Epworth total score. Higher age (r = 0.283; p < 0.001) and BMI (r = 0.170; p < 0.001) were significantly correlated with the Stop Bang score, whereas none of the variables was significantly correlated with the knowledge score.

Multivariable analysis
The results of a first linear regression, taking the Epworth score as the dependent variable, showed

Discussion
To the best of our knowledge, this study is the first large scale survey to assess the prevalence of OSA and its level of knowledge among the general Lebanese population. In this representative sample of Having arrhythmia and MI were both associated with higher daytime sleepiness. A systematic literature review proved an association between OSA and cardiovascular events 47 . In fact, up to 65% of patients who suffer from a cardiovascular disease are diagnosed with OSA 48 . This might be due to the fact that many shared risk factors are common between those two conditions 49 . Thus, current evidence of the association appears in middle-aged adults and patients with multiple cardiovascular risk factors 50 . In addition, OSA appears to play an important role in recurrence of Atrial Fibrillation (AF), but its independent role in the incidence of new onset AF remains unclear 50 . This might be due to the activation of the nervous system. Arousals from sleep stimulate sympathetic nervous system and hence cardioacceleration 51 .
Our results showed that a higher number of cigarettes smoked per day was significantly associated with higher daytime sleepiness, in agreement with previous studies 52,53 . While the association between cigarette smoking and OSA is plausible, the evidence is less than conclusive 54 . Cigarette smoking may worsen swelling and inflammation in the upper airway, affecting the neuromuscular function, and making snoring worse 55 . It may increase the severity of OSA through arousal mechanisms and trouble sleep architecture 56 . It has been hypothesized that each of these conditions adversely affects the other, leading to increased morbidity 52 .
Participants living in the North had less daytime sleepiness, whereas those living in Beqaa had higher daytime sleepiness compared to those living in Beirut. This could be explained by traffic-related pollution 57 , which induces higher risk of lung diseases 58 . Exposure to fine air particle, humidity and temperature might play an important role in the incidence and the severity of SDB 59 . More studies are needed to evaluate the association between the governorate of living and sleep apnea in Lebanon.
The used questionnaire helped finding that the population sample wasn't fairly aware of suggestive symptoms and complications of OSA, compared to studies conducted in France and Singapore also aiming to evaluate the knowledge of OSA among the population 23 24 . This finding proves the need of education programs in order to improve OSA knowledge.
As previously discussed, having CVAs was associated with lower knowledge scores compared to those who did not have CVAs. This correlates well with other studies 64,65 . In this regard, rigorous studies highly value the effect of CVAs on the cognitive domain, including attention, memory and language 65 .

Limitations
This cross-sectional research project has multiple limitations. Since it's a single point in time measurement, it cannot infer causality relationship. The lack of follow-up assessment increased the risk of attrition bias. Plus, the major respondents where form North Lebanon and the non-Arabic speaking participants were excluded, so the reached sample may not be representative of the whole population. Reliance on closed-ended questions may have limited the accuracy of obtained information, leading to over or under evaluated symptoms. Moreover, investigators were available for any clarifications if needed. However, social bias should be minimal as the anonymity was assured.
Individuals might have tended to misrepresent self-reported behaviors and shift the response to the more socially acceptable one, instead of selecting the "real" answer, to avoid negative evaluation.
Furthermore, the Arabic translation of the existing questionnaire 24 was not specifically validated in Lebanon. Lastly, it is difficult to determine whether some complications followed OSA in time or sleep apnea resulted from the already present pathology. 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 present study shed light on the overall knowledge of OSA among the Lebanese population.
Complications are still poorly known, as are certain suggestive symptoms. Given the local relevance

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 was responsible for the data collection and designed 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.