Validation of NoSAS (Neck, Obesity, Snoring, Age, Sex) score as a screening tool for obstructive sleep apnea: Analysis in a sleep clinic

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www.journalpulmonology.org

ORIGINAL

ARTICLE

Validation

of

NoSAS

(Neck,

Obesity,

Snoring,

Age,

Sex)

score

as

a

screening

tool

for

obstructive

sleep

apnea:

Analysis

in

a

sleep

clinic

J. Coutinho

Costa

a_,_∗

_,

_A.

_{Rebelo-Marques}

b_,c

_,

_J.N.

_Machado

a

_,

_J.M.R.

_Gama

d

_,

_C.

_Santos

e

_,

F. Teixeira

a_,e

_,

_J.

_Moita

a_,e

a_Pneumology_B_Unit,_University_Hospital_Centre_of_Coimbra_---_Hospital_Geral,_Coimbra,_Portugal

b_USF_Condeixa,_ACeS_Baixo_Mondego,_ARS_Centro,_Coimbra,_Portugal

c_Faculty_of_Medicine,_University_of_Coimbra,_Coimbra,_Portugal

d_Centre_of_Mathematics_and_{Applications,}_University_of_Beira_Interior,_Covilhã,_Portugal

e_Sleep_Medicine_Centre,_University_Hospital_Centre_of_Coimbra_---_Hospital_Geral,_Coimbra,_Portugal

Received31October2018;accepted16April2019 Availableonline10June2019

KEYWORDS NoSASscore; Obstructivesleep apnea; Screening; Prioritization; Diagnosis Abstract

Introduction:Screeningmethodshavebecomeincreasinglyimportantduetothegrowing num-berofpatientssuspectedofhavingobstructivesleepapnea(OSA)beingreferredtosleepclinics. TheLausanneNoSAS(Neckcircumference,Obesity,Snoring,Age,Sex)scoretestisasimple, efﬁcient,andeasilyemployedtoolenablingidentiﬁcationofindividualsatriskforthedisease. Thescorerangesfrom0to17andthepatienthasahighprobabilityofOSAiftheyhaveaNoSAS scoreof8orhigher.

Objectives: ToevaluatetheperformanceoftheNoSASscoreasascreeningtoolforthediagnosis ofOSAinasleepclinic.

Methods:Prospectively,for12months,weincludedallthepatientsreferredbyprimarycare physicianstooursleepunitforclinicalevaluationwhohadundergonein-labpolysomnography (PSG)andcompletedtheNoSASscore.Thistestassigns4pointsforaneckcircumferenceof morethan40cm,3pointsforabody-massindexof25kg/m2_to_less_than₃₀_kg/m2_or₅_points

forhavingabody-massindexof30kg/m2_or_more,₂_points_for_snoring,₄_points_for_being_older

than55yearsofageand2pointsforbeingmale.

Results:Ofthe294patients,70.7%weremale,aged53.5_±12.1years,withaneck circumfer-enceof41.0±3.6cmandaBMIof30.8±5.1kg/m2_._OSA_was_present_in_84.0%_of_the_patients,

34.8%withmoderateOSAand36.4%severeOSA.UsingtheNoSASmodelforthepredictionofall

∗_{Corresponding}_author.

E-mailaddress:[email protected](J.CoutinhoCosta).

https://doi.org/10.1016/j.pulmoe.2019.04.004

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OSA,moderate/severeOSAandsevereOSA,theareaundertheROC(ReceiverOperating Char-acteristic)was0.770(IC95%:(0.703;0.837),p<0.001),0.746(IC95%:(0.691;0.802),p<0.001) and0.686(IC95%:(0.622;0.749),p<0.001),respectively,thusconﬁrmingthediagnosticability oftheNoSASmodel.

WithaNoSASscore≥7,thesensitivityandpositive predictivevalue(PPV)were94.3%and 87.6%forallOSA,94.9%and62.8%formoderate/severeOSAand100%and33.8%forsevereOSA, respectively.Withthesamecut-off,thenegativepredictivevalue(NPV)formoderate/severe andsevereOSAwere67.9%and100%,respectively.EachincreaseintheNoSASscorewas asso-ciatedwithanincreaseintheprobabilityofOSA,reachinga97%OSAprobabilityforascoreof 17.

Conclusions:The NoSASscore showed high sensitivityandPPVfor OSAwith speciﬁcityand diagnosticaccuracysteadily increasingwithhigherscores.Furthermore,alowscoreshowed highpredictivevaluefortheexclusionofmoderate/severeOSA.Overall,ourresultssuggest that,inprimarycare,thisscorecanbeapowerfultoolforstratifyingandprioritizingpatients inthediagnosis ofOSA.Nevertheless,more studiesareneededto evaluatethe efﬁcacyof thisscoreinhospitalhealthcare,inyoungerpopulations,withapredominanceoffemaleand non-obeseindividualsorincardiovasculardisease.

http://creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction

Obstructive sleepapnea syndrome (OSA) is characterized by obstruction of the upper respiratory tract leading to increased respiratory effort with inadequate ventilation. Theobstructioniscausedbythecollapseofthepharynxdue tothedecreaseofthemuscletonethatoccursduringsleep; individualsthatpresentriskfactorsarepredisposedtothis situationoccurring.Theseepisodesareinevitably accompa-niedbydesaturation,increasedactivityofthesympathetic nervoussystemwithfrequentarousals.Snoringanddaytime sleepinessarethemaincomplaintsandobservedapnea is themostspeciﬁcsymptom.

Individualswithhiddendiseaseareathighriskof medi-calcomorbidities and of road accidents due to excessive sleepiness. There is an independent association of OSA withincreased morbidity and mortality due to metabolic disorders, neurovascular and cardiovascular disease, and impairedneurocognitivefunction,evenifasymptomatic.1---3

The prevalence of this pathology depends signiﬁcantly onthe populationstudied andthedeﬁnitionofOSA crite-ria (study methodology and threshold of apnea hypopnea index(AHI)used).4,5_According_to_Heinzer_et_al.,_the

preva-lenceisabout23.4%inwomenand49.7%inmen.6_Estimates

showthatthemale/femaleratiorangesfrom2:1to4:1.It can appearin all age groups, however, studies show that womenhave ahigherincidenceintheagegroupabove65 years,prevalenceincreasingaftermenopause,whileinmen itoccursbetween45and64yearsofage.7

Screeningmethodshavebecomeincreasinglyimportant dueto thegrowing number of patients suspectedof hav-ingobstructivesleepapneabeingreferredtosleepclinics. Thedifﬁcultyofdiagnosisofthispathologyisrelatedtothe availabilityandaccessibilityofcardiorespiratorysleep stud-ies(laboratory diagnosis).Consequently,prioritizationand screeningmethodsthatappropriatelystratifyareessential.

A simple and reliable method of screening certain popu-lations, namelyhigh-risk groups, isneeded. Thechoice of screening method will depend onits ability toachieve a speciﬁcobjective:toincludepatientswithOSAfor appropri-atesleeptesting;todetectthosewithmoreseveredisease facilitating earlydiagnosis and treatment; andtoexclude patientswithoutOSAorwithoutsevereOSA,whose evalua-tionandtreatmentislessurgent.

Numerousclinical prediction models have been devel-opedbasedonclinical, demographics andanthropometric variables.8,9 _A _recently _proposed _screening _method _is _the

LausanneNoSASScoretest(AppendixA),asimple,efﬁcient, andeasilyemployedtoolenablingidentiﬁcationof individu-alsatriskforthedisease.10_This_score_assess₅_parameters:

Neckcircumference,Obesity,Snoring,Age,Sexandassigns4 pointsforhavinganeckcircumferenceofmorethan40cm, 3 pointsfor havinga body-massindex of25kg/m2 _to_less than30kg/m2 _or₅ _points_for _having_a_body-mass_index_of 30kg/m2 _or _more,₂ _points_for_snoring, ₄_points_for _being olderthan55yearsofageand2pointsforbeingmale.The scorerangesfrom0to17andthepatienthasahigh prob-ability of OSA if they have a NoSAS score of 8 or higher. Thus,ithelpstoidentifyindividualsatriskforthedisease and rule out others without risk, witha negative predic-tivevalue(NPV)of90%and98%intwoethnicallydifferent population-basedcohorts.10

Methods

Objective

Thepresentstudyaimedtoevaluatetheperformanceofthe NoSASscoreasascreeningtoolforthediagnosisofOSAina respiratoryandsleepmedicineclinic.

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Studydesign

Prospectivestudy,12monthsinduration,beginningin Jan-uary 2017, we considered consecutively all patients with suspicious sleep disorder, referred by primary care physi-cians to our sleep unit for clinical evaluation and who underwentin-labpolysomnography(PSG).

Duringtheclinicalconsultation,everypatientwasasked if they accepted participation in the study, regardless of thereasonsforbeingreferred,whichincludedreferralfor isolatedsymptoms or clinical suspicionof aspeciﬁc sleep disorder(e.g.OSA,insomnia,parasomnia).

All patients included were required to complete the NoSAS questionnaire,10 _with _information _concerning _neck

circumference, body mass index (BMI), snore, age and gender, ultimatelycollectedbyaclinician.We also evalu-atedother parametersnamelyEpworth’s score,tiredness, observed apnea and high blood pressure (blood pressure >140/90mmHgormaketreatmentforhypertension).

Theresearchstaffdidnotinterferewiththe interpreta-tionorcompletionofthequestionnaires.

Patients previously diagnosed with OSA, those unable to read and/or write, additional diagnoses obtained throughout the sleepstudy (like central sleepapnea and obesity/hypoventilationsyndrome)andallcasesof techni-cal error during data collection, were excluded from the study.

Sleepstudies,scoringanddiagnosis

At the specialized sleep center, all patients underwent a standardPSG,usingthepatient’susualbedtimeovernight. Astandardized settingmade upofsurface electrodeswas used and included: electrocardiogram, electroencephalo-gram, electrooculogram, submental and lower limb EMG. Besides this data, additional information was collected regardingoronasalairflow(thermistorandpressuresensor), thoracicandabdominalrespiratoryeffort,pulseoximetry, snoringandbodypositionsensoring.AcertifiedPSG techni-cianscoredthePSGrecordings,ensuringcorrectassembly, underthesupervisionofasleepphysicianwhoreviewedand validatedthefinalreports.Thesleepphysicianand techni-cian were both blinded tothe study report (both clinical information and NoSAS). The scoring was done manually, following therecommendations of theAmericanAcademy of Sleep Medicine.11 _Apnea _was _defined _as_a _decrease _of

at least 90% of airflow from baseline, lasting 10 second or longer.Hypopneawasdefinedasa decreaseofatleast 30%ofairflowfrombaseline,lasting10second,associated witheitheranarousalora≥3%O2saturationdecrease.The meannumberofapneasandhypopneasperhoursofsleep (apnea---hypopnea index [AHI]) wascalculated. Both diag-nosis and severity of OSA were classified based upon the AHI: >5---15/h---mild, >15---30/h--- moderate,and >30/h ---severe.11,12

Additionaldiagnosesobtainedthroughoutthesleepstudy weredeﬁnedaccordinglytotheInternationalClassiﬁcation ofSleepdisorders-third edition.13 _However,_our _study_was

exclusively focused on OSA, so all other diagnoses were ignoredorexcluded.

Statisticalanalysis

StatisticalanalysiswasmadeusingtheIBMSPSS® statistical program,version25(theStatisticalPackagefortheSocial Sciences).

Thecategoricalvariablesweredescribed with frequen-cies and percentages and the quantitative variables with mean,median,standarddeviation,maximumandminimum. AllassociationsbetweenthepresenceofOSAandeachofthe possiblerisk factorswereestablishedusinglogistic regres-sion,whichestimatedtheiroddsratios(ORs).

To evaluate the performance of the NoSAS score in predictingOSA, sensitivity, speciﬁcity, negativepredictive values (NPVs) and positive predictive values (PPVs) were estimatedfordifferentAHIcut-offs.

TomeasurethediagnosticabilityoftheNoSASscorefor differentAHI cut-offs,wealsodeterminedtheareaunder thereceiveroperatingcharacteristic (ROC)curve andthe value of the score where both sensitivity and speciﬁcity maximized.

FortheevaluationoftheinfluenceoftheNoSASscorein theestimationoftheprobabilitiesofOSAseverity,anordinal regressionmodelwasfittedwiththelogitlinkfunction.The Waldtestwasconsideredsignificantwhenitsp-valuedidnot exceed0.05.

Results

Of the 294 patients, 70.7% were male, aged 53.5±12.1 years, with a neck circumference of 41.0±3.6cm and a BMIof 30.8±5.1kg/m2_._OSA _was_present _in _84.0% _of _the patients,28.8%withmildOSA, 34.8%moderateand36.4% severe.

Descriptivesummarystatistics,NoSAScharacteristicsand comparison of OSA and non-OSA groups are displayed in

Table1.Althoughgreater intheOSA group,tirednesswas

theonlycharacteristicwhichwerenotsigniﬁcantlydifferent betweentheOSAandnon-OSAgroup.

UsingtheNoSASmodelforthepredictionofallOSA, mod-erate/severeOSAandsevereOSA,theareaundertheROC curve (AUC) was0.770 (IC95%: (0.703; 0.837), p<0.001), 0.746(IC95%: (0.691; 0.802),p<0.001) and 0.686(IC95%: (0.622;0.749),p<0.001),respectively,thusconﬁrmingthe diagnosticabilityoftheNoSASmodel.

The sensitivity, speciﬁcity, PPV, and NPV for all OSA, moderate/severeOSA, and severeOSA aresummarized in

Table2.WithaNoSASscore≥7,thesensitivityandpositive

predictivevalue(PPV)were94.3%e87.6%forallOSA,94.9% and62.8%formoderate/severeOSAand100%and33.8%for severeOSA, respectively. Withthesame cut-off,the neg-ativepredictivevalue(NPV)for allOSA, moderate/severe OSAandsevereOSAwere50%,67.9%and100%,respectively. Asthescoreincreasedfrom7to12,thespeciﬁcityandPPV increasedcontinuouslyfrom29.8%to83%and87.6%to94.7% for all OSA, 16.1% to 74.6% and 62.8% to80% for moder-ate/severeOSA,and13.7%to57.8%and33.8%to42.7%for severeOSA,respectively.

The predicted probabilities of having OSA, moder-ate/severeOSA, andsevere OSA areshownin Table3. As NoSASscoreincreasedfrom2to17,theprobabilityof hav-ingOSA,moderate/severe OSA, andsevere OSAincreased

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Table1 SummarystatisticsofthepatientpopulationandcomparisonofOSAandnonOSAgroup.

Variable OSA OR---yes/no(CI95%);

logisticregression pa Yes N=247 (84.0%) No N=47(16.0%) Age(years) 1.062(1.032;1.093) <0.001 Average_±SD 55.81_±11.43 47.49_±13.06 Median(mín;máx) 56(20;82) 47(23;77) Tiredness(n)(%) Yes 150(60.7) 22(46.8) 1.757(0.938;3.291) 0.078(NS) No 97(39.3) 25(53.2) 1 Observedapnea(n)(%) Yes 179(72.5) 16(34.0) 5.100(2.623;9.915) <0.001 No 68(27.5) 31(66.0) 1

Pessure(highblood)

Yes 150(60.7) 14(29.8) 3.645(1.855;7.161) <0.001 No 97(39.3) 33(70.2) 1 Epworth’sScore 1.067(1.004;1.135) 0.036 Average_±SD 10.97_±5.35 9.15_±5.19 Median(mín;máx) 11(1;24) 8(2;20) Minimumsaturation 0.731(0.657;0.814) <0.001 Average_±SD 78.41_±10.63 88.30_±4.34 Median(mín;máx) 81.0(0.0;92.0) 90.0(74.0;95.7) Neckcirc.>40cm(n)(%) Yes 150(60.7) 9(19.1) 6.529(3.023;14.104) <0.001 No 97(39.3) 38(80.9) 1 Obesity(n)(%) <0.001 BMI<25 14(5.7) 13(27.7) 1 BMI25---30 102(41.3) 21(44.6) 4.510(1.854;10.973) 0.001 BMI≥30 131(53.0) 13(27.7) 9.357(3.634;24.096) <0.001 Snoring(n)(%) Yes 241(97.6) 42(89.4) 4.782(1.396;16.380) 0.013 No 6(2.4) 5(10.6) 1 Gender(n)(%) Female 63(25.5) 23(48.9) 1 Male 184(74.5) 24(51.1) 2.799(1.477;5.305) 0.002 NoSAS 1.310(1.196;1.435) <0.001 Average±SD 12.35±3.51 8.43±3.86 Median(mín;máx) 13(3;17) 9(0;15) a_Teste_de_Wald.

Abbreviations:OR=oddsratio;CI=ConﬁdenceInterval;BMI:bodymassindex;OSA:obstructivesleepapnea;NS:notsigniﬁcant. continuouslyfrom35%to97%, 12%to85%and 5%to53%,

respectively.Thistrend,presentinallgroupsisillustrated inFig.1.

The predicted probabilitiesof havingOSA ofa speciﬁc severity are illustrated in Fig. 2. With each incremental increaseinthescorefrom0to7,theprobabilityofhaving nosleepapneadiminished,whiletheprobabilityofhaving mild,moderate, orsevere sleepapneaincreased continu-ously.Withany scoregreater than 7,only the probability ofhavingmoderateorseveresleepapneaincreased.Witha scoregreaterthan13,onlytheprobabilityofhavingsevere sleepapneaincreased.

Discussion

This studyshows that,in apopulation referredtoasleep medicineclinic,aNoSASscore≥7hashighsensitivity(94.3%) andPPV(87.6%)forthediagnosisofOSAandthatthegreater the NoSAS score, reﬂecting a higher cumulative score of known risk factors, the greater the probability of sleep apnea,particularlymoderatetoseveresleepapnea(Fig.2). TheprobabilityofOSAforascoreof7is67%andincreases continuouslyto73%,78%,86%,91%,95%and97%witha step-wise increase of the NoSASscore to8, 9, 11, 13, 15 and 17. This performance is due tothe increasing probability

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Table2 PredictiveparametersofeachNoSASscorecut-offsfordifferentAHIlevels(n,numberofpatientsintheAHIgroup whoscoredtheNoSASscoreindicatedorhigher;percentageoutofthe294patients).

AllOSA(AHI>5)

NoSASscorecut-off N(%) Sensitivity Speciﬁcity PPV NPV

≥1 247(84.0) 100 2.1 85.5 100 ≥3 247(84.0) 100 10.6 85.5 100 ≥4 246(83.7) 99.6 10.6 85.4 83.3 ≥5 241(82.0) 97.6 21.3 86.7 62.5 ≥6 235(79.9) 95.1 27.7 87.4 52.0 ≥7 233(79.3) 94.3 29.8 87.6 50.0 ≥8 216(73.5) 87.4 40.4 88.5 38.0 ≥9 210(71.4) 85.0 44.7 89.0 36.2 ≥11 190(64.6) 76.9 55.3 90.0 31.3 ≥12a ₁₄₂_(48.3) _57.5 _83.0 _94.7 _27.1 ≥13 141(48.0) 57.1 83.0 94.6 26.9 ≥15 91(31.0) 36.8 95.7 97.8 22.4 ≥17 42(16.7) 17.0 100 100 18.7 18 0(0.0) 0.0 100 --- 16.0

Moderate/severeOSA(AHI>15)

≥1 176(59.9) 100 0.8 60.0 100 ≥3 176(59.9) 100 4.2 60.9 100 ≥4 176(59.9) 100 5.1 61.1 100 ≥5 173(58.8) 98.3 11.0 62.2 81.3 ≥6 169(57.5) 96.0 15.3 62.8 72.0 ≥7 167(56.8) 94.9 16.1 62.8 67.9 ≥8 158(53.7) 89.8 27.1 64.8 64.0 ≥9 155(52.7) 88.1 31.4 65.8 63.8 ≥11 142(48.3) 80.7 41.5 67.3 59.0 ≥12 120(40.8) 68.2 74.6 80.0 61.1 ≥13a ₁₂₀_(40.8) _68.2 _75.4 _80.5 _61.4 ≥15 79(26.9) 44.9 88.1 84.9 51.7 ≥17 41(13.9) 23.3 99.2 97.6 46.4 18 0(0.0) 0.0 100 --- 40.1

SevereOSA(AHI>30)

≥1 90(30.6) 100 0.5 30.7 100 ≥3 90(30.6) 100 2.5 31.1 100 ≥4 90(30.6) 100 2.9 31.3 100 ≥5 90(30.6) 100 7.8 32.4 100 ≥6 90(30.6) 100 12.3 33.5 100 ≥7 90(30.6) 100 13.7 33.8 100 ≥8 85(28.9) 94.4 22.1 34.8 90.0 ≥9 85(28.9) 94.4 26.0 36.0 91.4 ≥11 76(25.9) 84.4 33.8 36.0 83.1 ≥12 64(21.8) 71.1 57.8 42.7 81.9 ≥13a ₆₄_(21.8) _71.1 _58.3 _43.0 _82.1 ≥15 44(15.0) 48.9 76.0 47.3 77.1 ≥17 22(7.5) 24.4 90.2 53.4 73.0 18 0(0.0) 0.0 100 --- 69.4

a _Cut-off_value_that_maximizes_both_sensitivity_and_{speciﬁcity.}

Abbreviations:AHI:Apnea---HypopneaIndex; OSA:obstructivesleepapnea;PPV:positivepredictivevalue;NPV:negativepredictive value.

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Table3 PredictedprobabilitiesofeachNoSASscorefordifferentAHIlevels(n,numberofpatientsintheAHIgroupwhoscored theNoSASscoreindicated;percentageoutofthe294patients).

NoSASscorecut-off AllOSA(AHI>5) Mod./severeOSA(AHI>15) SevereOSA(AHI>30)

N(%) Probability N(%) Probability N(%) Probability

0 0(0.0) 0.24 0(0.0) 0.08 0(0.0) 0.03 2 0(0.0) 0.35 0(0.0) 0.12 0(0.0) 0.05 3 1(0.4) 0.41 0(0.0) 0.15 0(0.0) 0.06 4 5(2.0) 0.48 3(1.7) 0.19 0(0.0) 0.08 5 6(2.4) 0.55 4(2.3) 0.23 0(0.0) 0.09 6 2(0.8) 0.61 2(1.1) 0.28 0(0.0) 0.11 7 17(6.9) 0.67 9(5.1) 0.33 5(5.6) 0.13 8 6(2.4) 0.73 3(1.7) 0.39 0(0.0) 0.16 9 20(8.1) 0.78 13(7.4) 0.45 9(10.0) 0.18 11 48(19.4) 0.86 22(12.5) 0.57 12(13.3) 0.25 12 1(0.4) 0.89 0(0.0) 0.63 0(0.0) 0.29 13 50(20.2) 0.91 41(23.3) 0.68 20(22.2) 0.34 15 49(19.8) 0.95 38(21.6) 0.78 22(24.4) 0.43 17 42(17.0) 0.97 41(23.3) 0.85 22(24.4) 0.53

Abbreviations:AHI:apnea---hypopneaindex;OSA:obstructivesleepapnea.

1.00 .90 .80 .70 .60 .50 .40 .30 .20 .10 .00 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 NoSAS Probability

All OSA (AHI > 5) Mod./severe OSA (AHI > 15) Severe OSA (AHI > 30) Interpolation line

Figure1 PlotofpredictedprobabilitiesfordifferentAHI lev-elswiththecorrespondingNoSASscore.

,70 ,60 ,50 ,40 ,30 ,20 ,10 ,00 -1 0 1 2 3 4 5 6 7 8 9 10 1112 13 14 1516 17 1819 NoSAS Probability Without OSA Mild OSA Moderate OSA Severe OSA Interpolation line

Figure 2 Plot of predicted probabilities for different OSA severitieswiththecorrespondingNoSASscore.

ofmoderatetosevereOSA foreachscoreabove7, reach-ingapredictedprobabilityof57%,68%,78%and85%fora scoreof11,13,15and17(Table3),respectively.Moreover, ascorelowerthan7showeddiscriminativepowertoexclude moderate/severeOSA,asreﬂectedbyaNPVof67.9%,72%

and81.3%forascoreof7,6and5,respectively.TheAUC was consistently high conﬁrming the diagnostic ability of theNoSASmodelforallOSAseverities.Furthermore, tired-nesswasstatisticallysimilarbetweentheOSAandnon-OSA groups,althoughtendingtobegreaterandmoreprevalent intheOSAgroup,reﬂectingtirednessasanequallycommon complaintsamongpatientswithvarioussleepdisordersand diseasesofotherorgans.

Owingtotherelativelyhigh prevalenceofundiagnosed OSA andits comorbidities,a trustworthy screeningtool is needed and mandatory for a prompt prediction of OSA. A quick and reliable screening test can enable clinicians withinaclinicalcontexttomakemoreinformeddiagnostic decisions,particularlywhenstratifyingpatients for unrec-ognized OSA and triage for further diagnostic assessment and treatment. Where theycan be usedand scored eas-ily,aspartofroutinedailypractice,questionnairescanbe appropriate tools for that purpose. Moreover, analysis of the questionnaireperformancein specific populationscan provide clinicians witha set of predictive parametersfor differentlevelsofOSAseverity,whichcanbeusedasa cru-cialguidefor diagnostic andtherapeutic decisions.Inour studythepresentresultsshowthattheNoSASquestionnaire, canaddgreatvalueandbeaveryusefulandpowerfultool in primarycare. Onthe basisofitsability todiscriminate participantswithclinicallysignificantdisorder,itsPPV,and itsNPV,NoSASscorecanbeaveryusefultoolfor triaging patientsdependingontheirscore:scoreof0---5---low proba-bilityofOSA,particularlymoderatetosevereOSA;score≥7 probableOSA;score≥12highprobabilityofOSA,specifically moderatetosevereOSA.

Numerous questionnaires and other clinical screening tools for OSA have been analyzed previously. The study of derivation andvalidationof NoSASscore of Marti-Soler et al., shows 8 asa threshold and the score wasdeﬁned aspositiveifit wasgreaterthan orequal to8pointsand negative if it was less than 8 points, on the basis of its abilitytodiscriminateparticipantswithclinicallysigniﬁcant

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disorder.10 _This_study_shows _an_AUC_of_0.74,_a_PPV_of_47%,

anNPVof90%andtheNoSASscoreperformedsigniﬁcantly betterthandidtheSTOP-Bang(AUC0.67)andBerlin(AUC 0.63)scores.10_In_our_cohort,_we_propose₇_as_a_threshold_and

obtainedanevenhigherperformancewiththeAUC0.770, aPPVof87.6%andaNPVof67.9%.

Moreover,therearesomepapers thatevaluatedNoSAS thatareworthmentioning.AccordingGuichardetal.,NoSAS wassimilartoBerlinandsigniﬁcantlybetterthanSTOP-Bang questionnaire(AUCwas0.72forNoSAS,0.66forSTOP-Bang and 0.69 for the Berlin score).14 _A _study _of _Tan _et _al.,

alsoevaluatedNoSASscoreandcompareditsperformance to the STOP-Bang and Berlin questionnaires.15 _The

sensi-tivity,speciﬁcity, and NPVand PPVof theNoSAS scoreto predictsevere sleepdisorder breathing(deﬁnedasanAHI of ≥30events/h), were 69.2%, 73.1%, 95.2%, and 23.7%, respectively.16 _They _concluded _that _its _performance _was

similar to the STOP-Bang and Berlin questionnaires, with AUC values of all three questionnaires clustered around 0.682---0.748.16 _According_Lye_et_al.,_the_sensitivity,

speci-ﬁcity, and NPV and PPV of the NoSAS score to predict severeOSA(AHI≥30events/h)was64.3%,70.0%,63.8%and 70.4%,respectively.16 _The_AUC_of_NoSAS_score_(0.724)_was

higherthanEpworthSleepinessScale(ESS)(0.544).16_They

concludedthat overall the NoSAS scoreperformed better than the ESS.16 _Moreover,_according _Cicero _et _al., _a _high

NoSASscorewasassociatedwithincreasedarterialstiffness, reducedrenalfunctionandincreasedmeanarterialpressure inalargecohortofhealthyindividuals.17_Although_this_study

didnotevaluateNoSASaccuracyanddonotsuggestacausal linkbetweenOSAandcardiovasculardisease,italsoshowed clinicalrelevanceinusingthisscoretoidentifyindividuals whoprobablyhaveOSAandahighercardiovascularrisk.17

InreferencetothevalidationofaPortugueseversionof theSTOP-Bang inprimarycare, byRebelo-Marques etal., usingthismodel for thepredictionof OSA,the diagnostic ability of the STOP-Bangwas relatively superior toNoSAS score(theAUCwas0.847).18

In conclusion, our results agree with and support the original data from Marti-Soher et al.,10 _and _can _help _to

implementandgeneralizeitsuseinprimarycare.

However, thisstudy has limitations that must be men-tioned.Thefactthatoursampleconsistedmainlyofobese menwithanaverageageofover50yearsmayhave condi-tionedourresults.

Conclusions

The NoSASscore showedhigh sensitivity and PPVfor OSA with specificity and diagnostic accuracy which steadily increased with higher scores. Furthermore, a low score showed high predictive value for the exclusionof moder-ate/severeOSA.Overall,ourresultssuggestthatthisscore issimple,efficient,andeasytoimplement,itenables iden-tificationofindividualsat riskofthediseaseandcanhelp primarycareclinicianstodecidewhichpatientsto investi-gate furtherwithanocturnal recording.Sothisscore can beapowerfultoolinprimarycareforstratifyingand prior-itizingpatientsinthediagnosisofOSA,dependingontheir score:score of 0---5--- low probabilityof OSA, particularly moderatetosevereOSA;score≥7probableOSA;score≥12

high probability of OSA, particularly moderate to severe OSA. Nevertheless, more studies are needed to evaluate theefﬁcacyofthisscoreinhospitalhealthcare,inyounger populations,withapredominanceoffemaleandnon-obese individualsorincardiovasculardisease.

Conﬂicts

of

interest

Theauthorshavenoconﬂictsofinteresttodeclare.

Appendix

A. NoSAS

score

1. Neckcircumference>40cm---4points 2. Obesity

- BMI25kg/m2_to_<30_kg/m2_---₃_points - BMI≥30kg/m2_---₅_points

3. Snoring--- 2points 4. Age>55years--- 4points 5. Sex:male--- 2points

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