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 software27. 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.
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 knowledge29. However, few scales consisted of questions addressed to the general population23,24. 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 questionnaire24 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 added24 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.
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)31 and the STOP-BANG questionnaire (SBQ)32. These two scales were chosen since the ESS is recommended to be included in screening evaluations33,34, and the SBQ for being superior in detecting OSA in the general population35,36.
ESS inquires about falling asleep in some circumstances, referring to the usual way of life. The Arabic form has been validated as an authentic tool37. The SBQ, also valid in Arabic, reported snoring behavior, tiredness, gasping, hypertension and neck circumference38. 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/m2 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 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.