Evaluation of thE BrussElls QuEstionnairE as a scrEEning tool for oBstructivE slEEp apnEa syndromE

1Department of Neurology, Hungarian Defence Forces Military Hospital, Budapest, Hungary Head of Department: Zoltán Szakács, MD, PhD 2Doctoral School, Semmelweis University, Budapest, Hungary Head of Department: Gyula Domján, MD, PhD 3Rehabilitation Centre, Combined Szent István and Szent László Hospital, Budapest, Hungary Head of Centre: Veronika Fáy, MD, PhD 4Department of Clinical Studies, Faculty of Health Sciences, Semmelweis University, Budapest, Hungary Head of Department: Klára Gadó, MD, PhD

INtRoDUCtIoN obstructive sleep apnea syndrome (oSAS) is a significant medical problem affecting at least 2-26% of the general population (1). It is an important risk factor for cardiovascular diseases (2). It can also cause a significant decrease in the quality of life (1). In the recent years, the relationship of oSAS and traffic accidents have been studied. oSAS was found to be a risk factor for falling asleep while driving, which increased the risk of accidents and near-misses (3). the most common daily syptoms of oSAS include excessive sleepiness, which is probably the source of the increased accident rate in oSAS patients. Fortunately, current research indicates that adequate oSAS treatment, including the therapy with continous positive airway pressure (CPAP), decreases the risk of accidents to the risk of the general population (4). this emphasizes the importance of proper diagnosis and treatment.
Polysomnography (PSG) is the gold standard for diagnosing obstructive sleep apnea/hypopnea syndrome (oSAHS), but is expensive and time-consuming (5), and therefore, cannot be used for screening. An effective screening tool may help detect patients who are at risk of having oSAHS so that proper diagnostic process can be initiated. Several questionnaires have been developed for this purpose (6).
the Epworth Sleepiness Scale (ESS) measures sleep propensity in order to differentiate persons with excessive daytime sleepiness (EDS). the ESS is a simple, self-report questionnaire (5). It contains eight questions Nóra Pető et al.
referred for nocturnal, laboratory-based polysomnography (PSG). PSG recordings were subsequently assessed by an expert somnologist. Sleep stages were distinguished and the Apnea-Hypopnea Index (AHI) was calculated according to the recommendations of the task Force of the American Academy of Sleep Medicine (4).
the Brussels questionnaire consists of objective questions (gender, age, weight, height, and history of traffic accidents), as well as symptoms constituing the clinical picture of oSAS (tab. 1). All the questions have three possible answers: YES, No, and DoN't KNoW. Daytime sleepiness is assessed with the ESS scale. the questions are attributed a value, reflecting the strength of the association between a given answer and the risk of motor vehicle accidents (MVAs) or the possibility of suffering from oSAS, as well as the level of uncertainty concerning this strength. the values are represented in table 2. the maximal possible score in this questionnaire is 24. If the result is 10 or higher, the screening is defined as positive and a medical advice should be required before a decision is reached on the driving license to be delivered (6).
concerning the possibility of falling asleep in various daily situations, with answers on an interval scale from 0 to 3 (5). the Berlin Questionnaire (BQ) was designed to identify individuals at higher risk of oSAHS in primary care. It contains 10 questions divided into three cathegories (6): -snoring severity, -EDS, and -history of hypertension or obesity. the patient is subsequently cathegorized into a low or high risk group (6). the StoP questionnaire contains four forced-choice (yes/no) questions related to snoring, tiredness during daytime, observed apneas and high blood pressure (acronym StoP) (5). Persons answering positively two or more questions are considered at high risk of oSAHS. High risk for oSAHS is defined when two or more questions are answered positively. the StoP-Bang questionnaire was developed on the basis of the StoP questionnaire. the second part of the StoP-Bang questionnaire consists of the following criteria: BMI > 35 kg/m 2 , age > 50 years, neck circumference > 40 cm, and gender (male) (6). the 4-V is a tool for the identification of moderate to severe oSAHS and consists of four criteria (gender, blood pressure, BMI, and self-reported snoring) (6). Most of the questionnaires have already been validated. StoP-Bang and BQ are the most commonly used oSAS questionnaires in primary care (6). the questionnaire developed by the obstructive Sleep Apnoea Working Group in 2013 in Brussells (termed Brussels Questionnaire) was created as a screening startegy for those who apply for a driver's license (7).
AIM the aim of this study was to evaluate the sensitivity and specificity of the Brussels Questionnaire for detecting oSAS. Evaluation of the Brussells Questionnaire as a screening tool for obstructive sleep apnea syndrome

MAtERIAL AND
In our study, the score of the survey was compared with the results of PM and PSG.
the data were analyzed using R and SPSS Statistica software. Sensitivity and specificity for AHI ≥ 15 were calculated. the discrimination ability of the questionnaire was evaluated using a receiver operating characteristic (RoC) curve that was calculated for the score of the questionnaire ≥ 10.

RESULtS
After the comparison of the results obtained with PM and the Brussels Questionnaire, the sensitivity and specificity of the questionnaire were calculated and amounted 0.64 and 0.49, respectively. AUC was 0.57 (tab. 3; fig. 1). After the comparison of the results obtained with PSG and the Brussels Questionnaire, the sensitivity and specificity of the questionnaire were calculated and amounted 0.83 and 0.55, respectively, with the AUC = 0.65 (tab. 3; fig. 2). the score of 10 points was found to be the optimal cut-off value with neither sensitivity nor specifity being priviledged at the cut-off point.
We have found that AHI measured with PG and with PSG had a significant positive correlation (Spearman's r = 0.628; p < 0.005). AHI scores measured with PG did not differ significantly between the groups of  there are some limitations to our study. It was performed on the patients of the Sleep Clinic and it may not be appropriate to transfer these conclusions to the asymptomatic population (10). However, we used inlaboratory polysomnography for the evaluation of 76 patients, which enabled us to find better predictive parameters.
Further research is needed to improve the Brussels Questionnaire and its specificity without compromising sensitivity.

CoNCLUSIoNS
We conclude that the Brussels Questionnaire is an acceptable screening tool for moderate and severe oSAS with the optimal cut-off point of 10. the Bruxelles Questionnaire is a simple tool for screening patients for oSAS before applying for driving license, with a sensitivity of 0.64, a specificity of 0.49 and AUC of 0.57. this correlates with the results of the most frequently used questionnaires.

DISCUSSIoN
In general, a good screening tool for oSAS should have a high sensitivity and a high negative predictive value, i.e. it is most important for this tool to appoint most of the patients with severe or moderate oSAS that are eligible for treatment. on the other hand, high specificity would help to avoid unnecessary costs from excessive resource utilization. Improving the specificitiy of a subjective screening tool, such as a questionnaire, is a huge challenge, because the symptoms of oSAS are not specific to the disease.
According to the recommendations of the obstructive Sleep Apnoea Working Group, a driver with an oSAS diagnosis may be authorized to drive if they have untreated mild oSAS with an AHI ≤ 15 (mild to moderate oSAS) (7). therefore, sensitivity and specificity were calculated for AHI ≥ 15 in our study.
Several questionnaires has been created for screening for oSAS, many of which has been validated in primary care, surgical setting or sleep clinics (1,5,8). Most of the tests validated in primary care have an acceptable sensitivity (tab. 4) (7). A meta-analysis of screening tests for oSA identified StoP-Bang scale as an excellent method for diagnosing severe oSAS, although it is an average predictor for the diagnosis of oSAS (9). However, another study reported the sensitivity of StoP-Bang for screening for moderate oSAS to be 0.93 in patients without a history of sleeping disorders for AHI ≥ 15 (2). the sensitivity and specificity of other screening tools, as well as the results of our study, are listed in table 4. the validation with the help of PSG is considered more accurate, given that it is the gold standard for the diagnosis (4). PM can be as accurate as PSG for the diagnosis in selected populations. According to the AASM guidelines, it can be used as an alternative to PSG for the diagnosis of oSAS in patients with a high pretest probability of moderate to severe oSAS (10). However, it is not the most appropriate method of general screening of asymptomatic population (10). the ease of administration and scoring are important characteristics of a screening tool. Brussels Questionnaire only takes a few minutes to complete, in addition, the interpretation of the result is simple.
our study indicates that among our sleep clinic patients, a Brussels score of 10 has the best discrimination for predicting moderate to severe oSA (AHI ≥ 15), as it was originally suggested by the obstructive Sleep Apnoea Working Group (7). in the last two rows, the results of this study are presented, using polygraphy (PG, portable monitor) and polysomnography (PSG) data, respectively.