The Utility of the Elbow Sign in the Diagnosis of OSA

CHEST The Utility of the Elbow Sign in the Dignosis of OSA Originl Reserch Mrk E. Fenton, MD, FCCP ; Kren Hethcote, MD ; Rhond Bryce, MD ; Robert Skomro, MD, FCCP ; John K. Reid, MD, FCCP ; John Gjevre, MD, FCCP ; nd Dvid Cotton, MD, FCCP SLEEP DISORDERS Bckground: Multiple questionnires hve been used to predict the dignosis of OSA. Such models typiclly hve multiple questions requiring cumultive scoring for interprettion. We wnted to determine whether simple two-prt questionnire hs predictive vlue in the pretest clinicl evlution for OSA. Methods: A questionnire consisting of two questions (1) Does your bed prtner ever poke or elbow you becuse you re snoring? nd (2) Does your bed prtner ever poke or elbow you becuse you hve stopped brething? ws prospectively dministered to ptients evluted in sleep disorders clinic prior to undergoing polysomnogrphy. Age, sex, BMI, nd Epworth Sleepiness Scle dt were collected. Results: Among the 128 ptients who hd polysomnogrm, nswering yes to being wkened for snoring incresed the OR of n pne-hypopne index 5/h 3.9 times compred with no. Answering yes to being wkened for pneic spells ws ssocited with n OR of 5.8 for n pne-hypopne index 5/h compred with no. These ssocitions did not differ by sex, BMI, Epworth Sleepiness Scle or nswering yes to the other question. Subjects. 50 yers old with OSA were less likely to report positive elbow sign nd hd significntly lower OR for being wkened for pneic spells thn those, 50 yers old. The sensitivity nd specificity of being wkened for pneic spells ws 65% nd 76%, respectively, with positive predictive vlue of 90%. Subgroup nlysis reveled tht in men with BMI. 31 positive elbow sign hd specificity of 96.6% for dignosis of OSA. Conclusions: Among ptients referred to sleep disorders clinic, positive response to being elbowed/poked for pneic spells significntly improves the pretest prediction of OSA. CHEST 2014; 145(3):518 524 Abbrevitions: AHI 5 pne-hypopne index; ESS 5 Epworth Sleepiness Scle; PPV 5 positive predictive vlue; PSG 5 polysomnogrphy; SDC 5 sleep disorders clinic OSA is common disorder 1 tht is ssocited with hypertension nd crdiovsculr disese, 2 incresed risk of motor vehicle ccidents, 3 nd incresed helthcre costs long with incresed bsenteeism nd decresed productivity in the workplce, 4 ll of which hve significnt individul nd societl consequences. OSA remins undignosed in significnt proportion Mnuscript received April 30, 2013; revision ccepted September 9, 2013. Affilitions: From the Division of Respirology, Criticl Cre nd Sleep Medicine, nd Clinicl Reserch Support Unit, University of Ssktchewn, Ssktoon, SK, Cnd. These dt were presented, in prt, t CHEST 2012, October 24, 2012, Atlnt, GA. Funding/Support: The uthors hve reported to CHEST tht no funding ws received for this study. of the popultion, 5 in prt relted to underrecognition; however ccess to testing fcilities is mjor brrier to dignosis in mny jurisdictions. In 2004, Flemons et l 6 reported the wit time for polysomnogrphy (PSG) in Cnd ws 4 to 35 months, 7 to 60 months in the United Kingdom, nd 2 to 10 months in the United Sttes. Other reviews suggest tht poor ccess remins significnt issue. 7 As result, Correspondence to: Mrk E. Fenton, MD, FCCP, Division of Respirology, Criticl Cre nd Sleep Medicine, 5th Floor Ellis Hll, Royl University Hospitl, 103 Hospitl Dr, Ssktoon, SK, S7N 0W8 Cnd; e-mil: mrk.fenton@ussk.c 2014 Americn College of Chest Physicins. Reproduction of this rticle is prohibited without written permission from the Americn College of Chest Physicins. See online for more detils. DOI: 10.1378/chest.13-1046 518 Originl Reserch

dpttions including incresed use of level 3 testing 8 nd even empiricl use of CPAP 9 hve been implemented. It hs lso ment tht witing lists for PSG re crefully monitored nd triged, often ccording to helth risk (crdiovsculr comorbidities) nd societl risk (eg, truck drivers). Multiple clinicl prediction models nd questionnires hve been published to id in the dignosis of OSA. 10 However, such models re cumbersome to use in the clinicl setting nd hve not been widely ccepted. Severl questionnires, 11-16 including the Berlin questionnire nd the STOP-Bng questionnire, hve been developed to improve pretest prediction of OSA. The Berlin questionnire hs been vlidted in the generl popultion but hs limited dignostic specificity. The STOP-Bng questionnire ws developed s preopertive screening tool to identify high-risk surgicl ptients who require dignostic test ing for OSA. As such, it chieves high sensitivity but low specificity with score under 4 with improved specificity t higher scores in ptients witing surgery. 17 In review, Abrishmi et l 18 reported tht mny questionnires re specific to certin popultions, but overll hve limited sensitivity nd specificity in the dignosis of OSA. All of the models nd questionnires developed to dte hve multiple questions nd domins to remember long with scoring systems tht mke them cumbersome nd of limited usefulness in the clinicl setting. We recognized tht mny ptients presenting to our sleep disorders clinic (SDC) often reported being elbowed or poked by their bed prtner becuse of snoring or witnessed pneic spells. We hypothesized tht simply sking bout this phenomenon, prticulrly relted to pneic spells, hs dignostic vlue in identifying ptients with OSA. Mterils nd Methods Ethics pprovl ws obtined from the University of Ssktchewn Biomedicl Reserch Ethics Bord (Bio No. 09-173). A simple selfdministered questionnire consisting of the following two questions ws developed: (1) Does your bed prtner ever poke or elbow you becuse you re snoring? nd (2) Does your bed prtner ever poke or elbow you becuse you hve stopped brething? It ws dministered prospectively to ptients referred with suspected sleep disorder to the SDC t the University of Ssktchewn. No exclusion criteri were pplied, nd no specific inquiry s to the existence of current bed prtner ws mde. Prticipnts ge, sex, BMI, nd Epworth Sleepiness Scle (ESS) score were lso collected. At the discretion of the responsible sleep physicin, who ws blinded to the results of the questionnire, ptients were referred on for further dignostic testing with either PSG or level 3 testing. Typiclly, level 3 testing is used for ptients without serious comorbidities deemed to hve high pretest probbility of OSA. However, such ptients my lso be referred for PSG depending on other considertions including, but not limited to, occuption nd distnce to cre. The mjority of testing within our region is coordinted through our SDC, which offers both ttended in-lbortory level 1 PSG nd home-bsed level 3 testing. Our SDC is the only source of level 1 testing loclly. However, there re both privte (direct cost to ptient) nd public (indirect cost to ptient) venues for level 3 testing. Ptients sent for PSG were plced on common witing list. PSG ws done ccording to the usul clinicl prctice in our SDC independent of individul questionnire results. PSG (Sndmn softwre, version 9.1; Mllinckrodt) ws done using stndrd Americn Acdemy of Sleep Medicine protocols 19 nd supervised by registered sleep technicins who were blinded to the questionnire results. The studies were scored in ccordnce with the Americn Acdemy of Sleep Medicine scoring mnul20 by registered sleep technicins nd interpreted by sleep physicins, ll of whom were blinded to questionnire results. For the purposes of this study, PSG result ws considered positive for OSA if the pne-hypopne index (AHI) ws 5/h in ccordnce with stndrd definitions of OSA. Vlues, 5/h were considered negtive. If split-night protocol ws used, only the dignostic portion of the night ws used to determine AHI. Individul mngement of ech ptient ws left to the discretion of the most responsible physicin independent of this study. Averge wit time for PSG in our SDC ws pproximtely 270 dys, despite creful trige nd implementtion of level 3 cre pthwy. Becuse of the unpredictbility of the dte when ll ptients would hve completed testing, we elected to smple our dtbse 1 yer fter closing enrollment. Bsic descriptive sttistics (men, medin, SD, rnge, nd proportion) were clculted s pproprite to describe the study subjects regrding ge, BMI, sex, ESS result, nd wkening by sleeping prtner for snoring or pne. x 2 nd t test nlyses were used to compre ctegoricl nd continuous chrcteristics, respectively, between those with nd without positive PSG result, defining positive result s n AHI 5. Positive PSG results were lso subdivided by severity into mild, moderte, nd severe ctegories, respectively, defined by AHI vlues of 5 to 14.9, 15 to 29.9, nd 30. Results were deemed sttisticlly significnt t P vlues,.05, nd ll nlyses were undertken using SPSS Sttistics for Windows, version 20.0 (IBM). Awkening by prtner for snoring nd wkening by prtner for pne in reltion to PSG outcome were initilly exmined individully using two seprte univrite logistic regression models. To ssess the consistency of these ssocitions in different popultion subgroups, the models were repetedly evluted, ech time with the inclusion of different covrite nd its interction with the key snoring or pne vrible. Overll sensitivity, specificity, positive nd negtive predictive vlues, nd positive nd negtive s were lso clculted. The Mntel-Henszel x 2 (liner-by-liner ssocition) test ws used to ssess whether sttisticlly significnt trend towrd higher probbilities of prtnerinitited wkening could be seen with incresing OSA severity. Additionl considertion ws given to the utility of evluting prtner-initited wkening for snoring or pne in conjunction with other well-estblished OSA risk fctors, specificlly for the purpose of developing n esily recognizble pretest profile of high probbility subjects in the context of this referred popultion. Only the vribles of BMI, ge, sex, nd prtner-initited wkening for snoring or pne were considered s potentil chrcteristics due to their reltively simple clinicl ssessment. Agin, for ese in rel-world ppliction, continuous vribles were ctegorized only utilizing two ctegories; for effective grouping, vrious cutpoints were evluted for ech vrible, determining divisions with strong positive predictive vlues (PPVs) nd t lest moderte degree of sensitivity. The vribles were entered into logistic regression model, nd sttisticlly significnt vribles were further exmined in ll possible two- to four-term combintions. Among these, subgroup of sttisticlly significnt chrcteristics producing the model with gretest estimte precision (nrrowest CIs) ws journl.publictions.chestnet.org CHEST / 145 / 3 / MARCH 2014 519

sought to mximize relibility of the subsequently generted predicted probbilities of OSA. For clinicl utility (ie, to identify resonbly lrge number of ptients in whom the dignosis is nerly certin), the finl model selected ws lso required to offer minimum specificity of 95% in ptients possessing the included chrcteristics nd minimum sensitivity of 20%. Results A totl of 902 ptients were seen in the SDC, 438 (48.6%) of whom consented to prticipte in this study between October 1, 2009, nd September 30, 2010. Three hundred twelve men (71.2%) nd 126 women (28.8%) elected to prticipte. Forty ptients (9.1%) were not referred for further testing t the SDC (typiclly ptients with insomni or ptients lredy on CPAP nd one who hd lredy hd dignostic PSG), nd three were excluded becuse they hd only tretment/titrtion PSG dt vilble. Of the remining 399 subjects, 129 (29.5%) hd level 1 polysomnogrm by the time of dt smpling in October 2011. The remining 269 were either still witing for testing t the time of smpling the dtset or hd lterntive (typiclly level 3) testing done. Only PSG dt were used in this nlysis, nd only one subject ws ineligible due to n indeterminte PSG result. A totl of 94 men (73.4%) nd 34 women (26.6%) with n verge ge of 50.8 yers, verge BMI of 33.9 kg/m 2, nd medin ESS of 12 of 24 underwent PSG. Ninety-seven (75.8%) were found to hve n AHI 5/h. There ws no sttisticlly significnt difference in ESS score when compring positive nd negtive groups (Tble 1). There ws significntly higher proportion of men mong positive studies (83.5%) compred with negtive (41.9%) ( P,.001). Those with positive studies were lso hevier (BMI, 34.9 vs 30.8; P 5.01) nd showed trend to being older (ge, 51.8 yers vs 47.6 yers; P 5.053) compred with those with negtive studies ( Tble 2 ). Snoring A totl of 99 subjects reported being poked or elbowed for snoring, 81 of whom hd positive PSG, resulting in much higher proportion thn in the negtive PSG group. The positive nd negtive predictive vlues were 82% nd 46%, respectively. Answering yes to being wkened for snoring ws ssocited with n OR of 3.9 for hving positive PSG compred with nswering no. This ssocition did not show definitive difference by sex, BMI, ESS score, or nswering yes to being wkened for pneic spells. x 2 nlysis demonstrted tht s disese severity incresed there ws n incresed tendency to be wkened for snoring ( P 5.0004) ( Tble 3 ). The sensitivity nd specificity for n AHI 5/h of being wkened for snoring ws Tble 1 Subject Chrcteristics, Combined nd Strtified by OSA Totl Subjects (N 5 128) PSG Positive (n 5 97) PSG Negtive (n 5 31) No. Men Medin SD or IQR Min, Mx No. Men Medin SD or IQR Min, Mx No. Men Medin SD or IQR Min, Mx P Vlue Vrible Age, y 128 50.8 51.0 10.6 25, 78 97 51.8 52.0 10.1 25, 78 31 47.6 48 11.5 26, 70.053 BMI 128 33.9 31.8 8.1 20.4, 72.1 97 34.9 32.3 8.3 20.4, 72.1 31 30.8 29.6 6.7 20.7, 50.7.01 ESS 126 12 8, 16 0, 22 95 13 8, 16 1, 22 31 12 8, 14 0, 22.54 b ESS 5 Epworth Sleepiness Scle; IQR 5 interqurtile rnge; Mx 5 mximum; Min 5 minimum; PSG 5 polysomnogrphy. Subsequent P vlues from t test unless indicted. b P vlue from the Mnn-Whitney U test for comprison of medin vlues. 520 Originl Reserch

Tble 2 Subject Chrcteristics, Combined nd Strtified by OSA Totl PSG PSG Subjects Positive Negtive Vrible (N 5128) (n 597) (n 531) P Vlue Age, y, 40 y 18 (14.1) 9 (9.3) 9 (29.0) 40-49 39 (30.5) 31 (32.0) 8 (25.8) 50-59 41 (32.0) 33 (34.0) 8 (25.8) 60 nd 30 (23.4) 24 (24.7) 6 (19.4).06 older BMI, 30 46 (35.9) 29 (29.9) 17 (54.8) 30-34.9 42 (32.8) 33 (34.0) 9 (29.0) 35 or more 40 (31.2) 35 (36.1) 5 (16.1).03 Sex Femle 34 (26.6) 16 (16.5) 18 (58.1) Mle 94 (73.4) 81 (83.5) 13 (41.9),.001 Awkened for snoring Yes 99 (78.0) 81 (84.4) 18 (58.1) No 28 (22.0) 15 (15.6) 13 (41.9).002 Awkened for pne Yes 68 (55.3) 61 (64.9) 7 (24.1) No 55 (44.7) 33 (35.1) 22 (75.9).0001 Dt re given s No. (%). See Tble 1 legend for expnsion of bbrevitions. Subsequent P vlues from the x 2 test; number of subjects within specific vribles my not sum to outcome totl due to missing vlues. 84% nd 42%, respectively, with positive nd negtive s of 1.45 nd 0.37, respectively (Tble 4). Corresponding vlues for AHI 15/h nd 30/h re included in Tble 4. Apneic Spells A totl of 68 of 123 subjects who nswered the question reported being poked or elbowed for pneic spells, 61 of whom hd positive PSG. This ws gin higher compred with those with negtive PSG. Answering yes to being wkened for pneic spells ws ssocited with n OR of 5.8 for hving positive PSG, nd Tble 3 Frequency of Prtner-Initited Awkening by Disese Severity Prtner-Initited Awkening Awkened for snoring Not wkened for snoring Awkened for pne Not wkened for pne Apne-Hypopne Index 0-4.9 5-14.9 15-29.9 30P Vlue 18 (58.1) 24 (75.0) 19 (82.6) 38 (92.7).0004 13 (41.9) 8 (25.0) 4 (17.4) 3 (7.3) 7 (24.1) 17 (54.8) 10 (43.5) 34 (85.0),.0001 22 (75.9) 14 (45.2) 13 (56.5) 6 (15.0) Dt re given s No. (%). x 2 liner-by-liner ssocition for trend. Tble 4 Sensitivity, Specificity, nd Likelihood Rtios of Prtner-Initited Awkening by Disese Severity Prtner-Initited Awkening Apne-Hypopne Index 5 15 30 Awkened for snoring Sensitivity 81/96 (84.4%) 57/64 (89.1%) 38/41 (92.7%) Specificity 13/31 (41.9%) 21/63 (33.3%) 25/86 (29.1%) Positive 1.45 1.34 1.31 Negtive 0.37 0.33 0.25 Awkened for pne Sensitivity 61/94 (64.9%) 44/63 (69.8%) 34/40 (85.0%) Specificity 22/29 (75.9%) 36/60 (60.0%) 49/83 (59.0%) Positive 2.69 1.75 2.08 Negtive 0.46 0.50 0.25 gin did not show cler difference by sex, BMI, ESS score, nd response to the snoring question. When compring this ssocition between younger nd older subjects, s defined by 50 yers vs 50 yers, it becme pprent tht elbowing for pne is weker predictor in the older group compred with the younger group (OR, 18.9 vs 2.5; Breslow-Dy; P 5.047), due to both decresed elbowing for pne being reported in the older subjects with OSA nd incresed reporting for the sme in older subjects without OSA. However, x 2 nlysis showed n incresed likelihood of being wkened for pneic spells s disese severity incresed ( P,.0001) ( Tble 3 ). The overll sensitivity nd specificity ws 65% nd 76%, respectively, with PPV of 90% nd negtive predictive vlue of 40%. The positive ssocited with nswering yes to pneic spells ws 2.69 nd negtive likelihood rtio 0.46. Corresponding vl ues for AHI 15 nd 30, respectively, re included in Tble 4. Subgroup Anlysis: Elbow Sign Use In Modifiction of OSA Risk Strtifiction: The overll OSA prevlence in this selected popultion ws 75.8%, which genertes pretest odds of 3.13 (97 positive PSG/31 negtive PSG). We then used the pretest odds to clculte posttest odds in three selected subgroups of subjects in our popultion corresponding to low risk, intermedite risk, nd high risk, respectively ( Tble 5 ). Low-risk individuls in this dtset were represented by women younger thn 50 yers old with BMI, 30. Intermedite-risk cses were represented by women ged 50 nd 59 yers old with BMI under 30. Men younger thn 50 yers old with BMI between 30 nd 34.9 were recognized s high-risk group. Applying the s in these groups did not result in meningful differences between pretest risk nd journl.publictions.chestnet.org CHEST / 145 / 3 / MARCH 2014 521

Tble 5 Impct of Elbow Sign for Apne on Strtifiction of OSA Risk Across Low-, Intermedite-, nd High-Risk Groups Pretest Posttest Odds Posttest Risk Risk Risk, % Odds Positive Response Negtive Response Positive Response, % Negtive Response, % Low 12.5 0.14 0.38 0.066 27.7 6.2 Intermedite 50.0 1 2.7 0.46 72.9 31.6 High 95.0 19 51.1 8.8 98.1 89.8 Test in this tble refers to the question of prtner-initited wkening of pne. Pretest risk/odds refers to the likelihood of hving OSA prior to sking the question. Posttest odds/risk refers to the subsequent probbility of OSA fter positive or negtive response is received. posttest risk in the low- nd high-risk groups. In contrst, in the intermedite-risk group, positive response to being wkened for pneic spells incresed the pre-psg risk from 50% to 73%, which likely hs clinicl implictions in the lloction of dignostic testing. To Estblish/Confirm OSA Dignosis: A logistic regression model ws developed to predict OSA (see Mterils nd Methods section for detils). Bsed on this model, mle subjects with BMI of 31 or higher nd history of prtner-initited wkening for pne hd 95.1% predicted probbility of OSA ( Tble 6 ). In our smple, this profile fit 39 of the 128 subjects (29.4%) tht received PSG testing, 38 of whom hd n AHI 5/h (PPV 5 97.4%, 95% CI [86.5%, 99.9%]). Among the 123 subjects who responded to the question of prtner-initited wkening for pne, the specificity nd sensitivity for these combined chrcteristics were 96.6% nd 40.4%, respectively. In other words, ppliction of this model could hve estblished the dignosis of OSA (with cceptble certinty) in 38 of our subjects without PSG. Discussion This is not the first study to ttempt to use clinicl vribles to predict OSA, 11-17 nd similr to those stud- Tble 6 Logistic Regression Model for Clinicl Pretest OSA Prediction Predictor Estimte (SE) P Vlue OR 95% CI Intercept 20.871 (0.459) Awkened for pne Yes 1.406 (0.536).02 4.08 1.43, 11.65 No Reference BMI 31 Yes 1.19 (0.496).02 3.30 1.25, 8.72 No Reference Sex Mle 1.246 (0.519).02 3.48 1.26, 9.61 Femle Reference PPV 95.1% PPV 5 positive predictive vlue. See Tble 1 legend for expnsion of other bbrevition. Model-bsed probbility of positive PSG if ll three chrcteristics present. ies, we used PSG s the reference stndrd for comprison. However, it differs from previous models nd questionnires in severl importnt respects. Other questionnires consist of multiple questions nd domins tht require cumultive scoring to determine the risk of OSA (eg, Berlin questionnire, STOP-Bng). In contrst, our questionnire is simple nd esy to remember without n ssocited scoring system. Other questionnires hve been developed s screening tools for either the generl popultion (Berlin) or specific popultions such s preopertive ptients. The STOP-Bng questionnire hs high sensitivity (84%) nd reltively low specificity (56%) for n AHI 5/h in ptients witing surgery. This compres fvorbly to being wkened for snoring in our popultion, suggesting tht sking this question my be used s n lterntive to the STOP-Bng questionnire to screen for OSA in clinic ptients. Frney et l 21 nlyzed the STOP-Bng questionnire using vlidted STOP-equivlent questions in popultion referred for PSG, popultion similr to our popultion. Three nlyticl methods were constructed to nlyze the dt; however, ultimtely, liner model best estimted the probbility of OSA ccording to the ctegories of none, mild, moderte, nd severe bsed on AHI. As with other pproches, the questionnire needs to be interpreted by cumultive scoring method. Their conclusion ws tht the STOP-Bng questionnire my be useful in estimting the severity of OSA prior to PSG nd, hence, useful in triging the witlist for PSG. In contrst, the elbow sign is simple nd in popultion lredy known to hve high pretest probbility of OSA (similr to tht of Frney et l 21 ) chieves n cceptble degree of specificity (76%) overll, lbeit with low sensitivity (65%) for n AHI 5/h. Despite the cceptble specificity, using the elbow sign lone will result in missing pproximtely one-third of ptients with OSA. Tking this step further, men with BMI of 31 or higher nd positive elbow sign hve profile with high specificity (96.6%) for OSA. In other words, in nerly one-third of our subjects, the elbow sign could be used s n lterntive to PSG to estblish the dignosis of OSA. Although the elbow sign ppers to be better predictor in younger subjects, which would be in keeping with previous studies, 22 its presence 522 Originl Reserch

within the criteri here offered n improvement in specificity for the older subgroup (from 85.7% to 100%). This vlue ws on pr with specificity seen within the younger subgroup (93.3%), suggesting tht individuls who fit the profile re highly likely to hve OSA regrdless of ge. The overll sensitivity of the criteri within the older group did, however, drop from 49.1% to 30.9% in our smple when positive elbow sign ws included, suggesting tht the profile will fil to identify more older subjects with OSA thn it would younger ones. Similr to previous studies of witnessed pnes, 23,24 we found tht women re less likely to report prtnerinitited wkening for pneic spells (33.3% vs 70.9%, P 5.005), lthough this difference ws only borderline significnt for snoring (66.7% vs 87.7%, P 5.05) in our dt. Shepertycky et l 23 reported tht women re less likely to be wre of witnessed pneic spells, nd Vlipour et l 24 reported tht women with n AHI, 15/h were lso less likely to report witnessed pnes. However, when we exmined the predictive nture of positive elbow sign by compring mle nd femle subjects with OSA to those without OSA, no sttisticlly significnt difference ws seen between sexes in the degree to which the odds of OSA increse in those with positive elbow sign when compred with sexmtched counterprts without positive elbow sign. The prcticl ppliction of using the elbow sign in our center is to identify those ptients in whom dignostic testing cn be obvited nd tretment initited. Auto-CPAP is n ccepted nd proven method of CPAP titrtion 8 nd cn be done to determine individul pressure needs without witing for dignostic testing. The downstrem effects of this strtegy include fster time to tretment of the ptient in question nd less pressure on the PSG witing list with resultnt decreses in wit times for other ptients requiring PSG in whom the dignosis is less certin or other dignoses re being entertined. The economic impct of this pproch hs not been studied. However, reduction in direct cost (cost of PSG) nd indirect cost (eg, reduction in helth-cre cost) cn be nticipted. The economic impct of OSA hs been estimted s similr to the impct of dibetes ($132 billion/y). 21 Untreted OSA hs been shown to increse helth-cre utiliztion; tretment with CPAP reduces this nd its ssocited costs. 7,25 Therefore, we nticipte tht using this model in our center will result in lower direct nd indirect costs by reducing the time to strting tretment nd improvements in ccess overll. PSG is the ccepted gold stndrd for the dignosis nd stging of OSA 26 nd ws, therefore, deemed to be the best comprtor to estblish the efficcy of the elbow sign. This is similr to studies of other wellestblished questionnires.16,17 There re some obvious limittions to this study. It is reltively smll, single-center study of popultion with high pretest probbility for OSA, which limits its ppliction to the generl popultion or even generl medicl popultion. However, the results re likely generlizble to other sleep specilist clinics sttement tht needs to be further evluted. Clinicl Implictions The results of this prospective study suggest tht mong ptients referred to n SDC, simply sking if bed prtner wkens ptient becuse of pneic spells hs significnt dignostic vlue. In select group of ptients, it my obvite the need for PSG, n expensive, time-consuming test with limited vilbility. Thus, the elbow sign ppers to hve mjor implictions for the investigtion nd mngement of ptients with OSA nd importntly the mngement of witing lists for sleep testing. Acknowledgments Author contributions: Dr Fenton hd full ccess to the dt in this study nd tkes responsibility for the integrity of the dt nd ccurcy of dt nlysis. Dr Fenton: contributed to the study design, nlysis of dt, nd writing of the mnuscript. Dr Hethcote: contributed to the study design nd mnuscript review. Dr Bryce: contributed to dt nlysis, writing of the mnuscript, nd mnuscript review. Dr Skomro: contributed to the revision of the mnuscript with importnt intellectul content. Dr Reid: contributed to the revision of the mnuscript with importnt intellectul content. Dr Gjevre: contributed to the revision of the mnuscript with importnt intellectul content. Dr Cotton: contributed to the revision of the mnuscript with importnt intellectul content. Finncil/nonfinncil disclosures: The uthors hve reported to CHEST tht no potentil conflicts of interest exist with ny compnies/orgniztions whose products or services my be discussed in this rticle. Other contributions: The uthors thnk Michel Smith, MSc, nd Hyun Lim, PhD, for their ssistnce. References 1. Young T, Pepprd PE, Gottlieb DJ. Epidemiology of obstructive sleep pne: popultion helth perspective. Am J Respir Crit Cre Med. 2002 ;165(9):1217-1239. 2. McNichols WT, Bonsigore MR ; Mngement Committee of EU COST ACTION B26. Sleep pnoe s n independent risk fctor for crdiovsculr disese: current evidence, bsic mechnisms nd reserch priorities [published correction ppers in Eur Respir J. 2007;29(3):614]. Eur Respir J. 2007 ; 29 (1):156-178. 3. Krimi M, Eder DN, Eskndri D, Zou D, Hedner JA, Grote L. Impired vigilnce nd incresed ccident rte in public trnsport opertors is ssocited with sleep disorders. Accid Anl Prev. 2013 ;51:208-214. 4. Teng AY, Won C. Implictions of OSA on work nd work disbility including drivers. Clin Chest Med. 2012 ;33(4):731-744. journl.publictions.chestnet.org CHEST / 145 / 3 / MARCH 2014 523

5. Lurie A. Obstructive sleep pne in dults: epidemiology, clinicl presenttion, nd tretment options. Adv Crdiol. 2011 ;46 :1-42. 6. Flemons WW, Dougls NJ, Kun ST, Rodenstein DO, Whetley J. Access to dignosis nd tretment of ptients with suspected sleep pne. Am J Respir Crit Cre Med. 2004 ; 169 (6 ):668-672. 7. Leger D, Byon V, Lbn JP, Philip P. Impct of sleep pne on economics. Sleep Med Rev. 2012 ;16 (5 ):455-462. 8. Skomro RP, Gjevre J, Reid J, et l. Outcomes of home-bsed dignosis nd tretment of obstructive sleep pne. Chest. 2010 ;138 (2 ):257-263. 9. Skomro RP, Cotton DJ, Gjevre JA, et l. An empiricl continuous positive irwy pressure tril for suspected obstructive sleep pne. Cn Respir J. 2007 ;14 (3 ):159-163. 10. Flemons WW, Whitelw WA, Brnt R, Remmers JE. Likelihood rtios for sleep pne clinicl prediction rule. Am J Respir Crit Cre Med. 1994 ;150 (5 pt 1 ):1279-1285. 11. Wetherwx KJ, Lin X, Mrzec ML, Mlow BA. Obstructive sleep pne in epilepsy ptients: the Sleep Apne scle of the Sleep Disorders Questionnire (SA-SDQ) is useful screening instrument for obstructive sleep pne in disesespecific popultion. Sleep Med. 2003 ;4 (6 ):517-521. 12. Kpunii LE, Andrew DJ, Crowell DH, Perce JW. Identifying sleep pne from self-reports. Sleep. 1988 ;11 (5 ):430-436. 13. Netzer NC, Stoohs RA, Netzer CM, Clrk K, Strohl KP. Using the Berlin Questionnire to identify ptients t risk for the sleep pne syndrome. Ann Intern Med. 1999 ;131 (7 ):485-491. 14. Young T, Plt M, Dempsey J, Sktrud J, Weber S, Bdr S. The occurrence of sleep-disordered brething mong middleged dults. N Engl J Med. 1993 ;328 (17 ):1230-1235. 15. Hrldsson PO, Crenfelt C, Knutsson E, Persson HE, Rinder J. Preliminry report: vlidity of symptom nlysis nd dytime polysomnogrphy in dignosis of sleep pne. Sleep. 1992 ; 15 (3 ):261-263. 16. Chung F, Yegneswrn B, Lio P, et l. STOP questionnire: tool to screen ptients for obstructive sleep pne. Anesthesiology. 2008 ;108 (5 ):812-821. 17. Chung F, Subrmnym R, Lio P, Sski E, Shpiro C, Sun Y. High STOP-Bng score indictes high probbility of obstructive sleep pnoe. Br J Anesth. 2012 ;108 (5 ):768-775. 18. Abrishmi A, Khjehdehi A, Chung F. A systemtic review of screening questionnires for obstructive sleep pne. Cn J Anesth. 2010 ;57 (5 ):423-438. 19. Kushid CA, Littner MR, Morgenthler T, et l. Prctice prmeters for the indictions for polysomnogrphy nd relted procedures: n updte for 2005. Sleep. 2005 ;28 (4 ):499-521. 20. Iber C, Ancoli-Isrel S, Chesson AL, Qun SF. The AASM Mnul for the Scoring of Sleep nd Associted Events: Rules, Terminology nd Technicl Specifictions. 21st ed. Westchester, IL : Americn Acdemy of Sleep Medicine ; 2007. 21. Frney RJ, Wlker BS, Frney RM, Snow GL, Wlker JM. The STOP-Bng equivlent model nd prediction of severity of obstructive sleep pne: reltion to polysomnogrphic mesurements of the pne/hypopne index. J Clin Sleep Med. 2011 ;7 (5 ):459-65B. 22. Young T, Shhr E, Nieto FJ, et l ; Sleep Hert Helth Study Reserch Group. Predictors of sleep-disordered brething in community-dwelling dults: the Sleep Hert Helth Study. Arch Intern Med. 2002 ;162 (8 ):893-900. 23. Shepertycky MR, Bnno K, Kryger MH. Differences between men nd women in the clinicl presenttion of ptients dignosed with obstructive sleep pne syndrome. Sleep. 2005 ; 28 (3 ):309-314. 24. Vlipour A, Lothller H, Ruscher H, Zwick H, Burghuber OC, Lvie P. Gender-relted differences in symptoms of ptients with suspected brething disorders in sleep: clinicl popultion study using the sleep disorders questionnire. Sleep. 2007 ;30 (3 ):312-319. 25. AlGhnim N, Comondore VR, Fleethm J, Mrr CA, Ays NT. The economic impct of obstructive sleep pne. Lung. 2008 ; 186 (1 ):7-12. 26. Prctice prmeters for the indictions for polysomnogrphy nd relted procedures. Polysomnogrphy Tsk Force, Americn Sleep Disorders Assocition Stndrds of Prctice Committee. Sleep. 1997 ;20 (6 ):406-422. 524 Originl Reserch