원저 J Kor Sleep Soc / Volume 5 / December, 2008 가천의과대학교길병원신경과학교실 Comparing Sleep Questionnaires and Respiratory Disturbance Index in Obstructive Sleep Apnea syndrome patients Sang-Jun Park, M.D., Kee-Hyung Park, M.D., Dong-Jin Shin, M.D. Hyeon-Mi Park, M.D, Yeong-Bae Lee, M.D., Young-Hui Sung, M.D. Department of Neurology, Gil Medical Center, Gachon University of Medicine and Science, Incheon, Korea Background : The obstructive sleep apnea (OSA) syndrome is a potentially disabling condition characterized by excessive daytime sleepiness, disruptive snoring, frequent arousals and nocturnal hypoxemia. Self-reported sleep scales and questionnaires are easy to perform and useful method to evaluate the OSA patients. Each sleep scale and questionnaires are reported as a good screening tool for detection of OSA before polysomnographic evaluation. But there were no report about correlation between sleep scale and severity of OSA patients. We studied each sleep scales and questionnaires to confirm the correlation between each sleep questionnaire and the severity of OSA patients. Methods : Retrospectively consecutive 147 patients who carried out overnight polysomnogram from January 2005 to June 2007 were enrolled. All of the patients data were reviewed their sleep questionnaires which had done before polysomnographic evaluation. Sleep questionnaires were consisted of Epworth Sleepiness Scale (ESS), Stanford Sleepiness Scale (SSS), Insomnia Severity Index (ISI), Berlin questionnaire, Pittsburgh Sleep Quality Index (PSQI) and Beck Depression Index (BDI). OSA patients were divided into 3 groups according to severity by their respiratory disturbance index (RDI) score. Results : The OSA patients divided into normal, mild, moderate, severe group by their RDI score; Among sleep questionnaires, Berlin questionnaire and BDI had significantly correlated to OSA severity (P<0.05). Between them, Berlin questionnaire showed most positive correlation to OSA severity by RDI score (P<0.005). Conclusions : Our results revealed that Berlin questionnaire is a most significant scale for prediction of severity of OSA. Key Words : Obstructive sleep apnea, Respiratory disturbance index, Sleep questionnaire 서 론 수면중주기적상기도저항의증가로초래되는반복적인 * Address of correspondence Kee Hyung Park, M.D. Ph.D. Department of Neurology, Gachon University, Gil Medical Center 1198 Guwol-Dong, Namdong-gu, Incheon, 405-760, Korea Tel: +82-32-460-3346 Fax: +82-32-460-3344 E-mail: ghpark@gilhospital.com 호흡의중단 ( 무호흡, apnea) 또는감소 ( 저호흡, hypopnea) 를 폐쇄성수면무호흡증 (obstructive sleep apnea) 이라한다. 1 이런폐쇄성수면무호흡증은수면동안에반복적인상부기도의협착이일어나고이로인하여공기의흐름이막혀혈중산소포화도가떨어지고미세각성이일어나서수면이분절되는질환으로서흔히수면중잦은각성 (arousals) 을일으켜수면의양적, 질적저하를일으키며이결과로대개불면증과과도한주간졸음증등을유발한다. 이외에 Vol.5, No.2 / December, 2008 89
도집중력및인지기능의저하주간두통고혈압부정맥야간심허혈심근경색뇌졸중등과연관성이있고자동차사고및업무관련사고의증가와도높은관련성이있다는사실이밝혀지면서최근에점차관심이높아지고있다. 2-6 폐쇄성수면무호흡증을평가하는방법에는주관적인검사와객관적인검사가있다. 7 주관적인검사로는엡워스수면척도 (Epworth sleepiness scale, ESS) 8 가대표적인데이방법은간편하며적은비용으로졸리움정도를측정할수있는장점이있다. 하지만환자스스로체크하는지수이기떄문에신뢰성이낮으며국가별문화적차이를고려하지않아우리나라에서는표준화되지못했다는단점이있다. 이외에도스탠포드수면지수 (Stanford Sleepiness Scale, SSS), 불면증척도 (Insomnia Severity Index,ISI), 베를린설문지 (Berlin questionnaire), 피츠버그수면질척도 (Pittsburgh Sleep Quality Index, PSQI), 벡우울증척도 (Beck Depression Index, BDI) 들이수면설문조사로서사용되고있다. 객관적인검사로는다중수면잠복기검사 (mutiple sleep latency test, MSLT), 야간수면다원검사 (overnight polysomnography), 수면-각성활동도검사 (actigraphy) 가있으며이는실제수면상태를측정하는객관적이고신뢰성있는검사방법이다. 그러나검사시행의불편함, 고비용등의단점이있다. 7 폐쇄성수면무호흡증환자에서수면다원검사상의이상소견과임상증상과의관련성에대해아직논란이많이있고, 20 또한우리나라에서는수면다원검사가아직까지널리보편화되지않아한정된수면클리닉에서만검사할수있으므로환자를접근하는데있어서검사실소견뿐아니라환자의임상양상으로평가할수있는도구가필요하다. 따라서폐쇄성수면무호흡증이의심되는환자에서수면다원검사를하기에앞서환자의자각증상과이학적검사소견등을종합하여수면다원검사결과와비교분석해보는것은유용하다고생각된다. 특히지금까지국외에서다양한수면척도설문지사이의비교연구는많으나우리나라에서수면다원검사의결과에서나타난중등도와수면설문과의연관성을조사한연구는없었다. 따라서본연구에서는폐쇄성수면무호흡증환자들을대상으로수면척도설문지와수면다원검사에서의호흡장애지수의상관성을비교하여그관계를알아보고자하였다. 대상과방법 1. 환자군및대조군환자군은 2005 년 1월부터 2007 년 6월까지가천의대길병원신경과수면장애클리닉을방문하여수면척도설문지평가와야간수면다원검사 (overnight polysomnography) 를받은환자 147명을대상으로하였다. 야간수면다원검사에서수면무호흡증의정도는호흡장애지수 (respiratory disturbance index, RDI) 로평가하였고호흡장애지수는한시간의수면시간동안나타나는무호흡이나저호흡이 5회이상일때로정의하였으며미국수면의학회 (American Academy of Sleep Medicine) 에서제시하는호흡장애지수 (Respiratory Disturbance Index(RDI)) 에따라 4그룹으로나누었다. 10 대조군은시간당 RDI가 5회미만인군으로정하였고환자군은 RDI 가 5 이상 15이하일때경한군으로 15에서 30 사이일때를중등도군으로 30이상일때를심한군으로분류하였다. 2. 수면설문수면지수설문지는현재표준화중인주간수면과다의평가를위한엡워스수면척도 (Epworth Sleepiness Scale, ESS), 스탠포드수면척도 (Stanford Sleepiness Scale, SSS), 불면증의평가는불면증척도 (Insomnia Severity Index, ISI), 수면무호흡에대한평가항목은베를린설문지 (Berlin questionnaire), 수면의질을평가하는피츠버그수면질척도 (Pittsburgh Sleep Quality Index, PSQI) 를이용하였고대상환자들의우울증정도를평가하기위해한국판벡우울증척도 (Beck Depression Index, BDI) 도함께검사하였다. 3. 야간수면다원검사 (overnight polysomnography) 환자군전원에대하여하룻밤동안 Grass-Telefactor 사의 Comet 수면다원검사를시행하였으며뇌파와안전도 (left outer canthus-a1, right outer canthus-a2), 턱근전도를통해수면의단계와각성을판정하였다. 호흡량은 90 수면
열전대 (thermistor) 와압력감지기로, 호흡운동은흉곽벨트 (strain gauge) 를이용해측정하였으며그외산소포화도 (finger plus oximetry) alc 체위센서, 심전도검사 (modified pulse oximetry) 를병행하였다. 11 저호흡은호흡운동이유지된상태에서호흡이 10초이상완량이 30% 이상감소를보이건, 10초이상명확한호흡량감소와동반하여뇌파상의각성이있거나산소포화도가 4% 이상감소되는경우로, 무호흡은 10초이상완량이 90% 이상감소를보이는경우로정의하였으며한시간의수면동안발생하는무호흡과저호흡횟수합의평균을 RDI 로정의하였다. 12 4. 통계분석각각의인자의평균과빈도를기본으로구하였고, 두군간에연속변수 (continuous variables) 의경우는 t 검정을범주형변수 (categorical variables) 의경우 χ² 검정을이용해비교하였다. 통계적처리는 SPSS(statistical package for social science Ver 12.0) 을이용하였다. 결과대상환자는총 147명으로남자 129명 (87.7%), 여자 18 명 (12.3%) 이었으며대상환자군중폐쇄성수면무호흡증환자는 122명 (82.9%) 이였으며남성 95.0%, 여성 5.0% 를차지하였다. 이들을다시폐쇄성수면무호흡의심각도에따라세분화하면경도 18%, 중등도 23%, 중증 59% 였다. 네군간에무저호흡지수 (apnea hypopnea index, AHI), 목둘레 (neck circumference, NC), 허리둘레 (Waist circumference, WC) 에있어서유의한차이가관찰되었으나연령, 체질량지수 (body mass index, BMI), 수면효율 (sleep efficiency) 에서는유의한차이는관찰되지않았다 (Table 1). 정상군과환자군을대상으로한수면지수설문지평가에서는 BDI, Berlin questionaire 에서 OSA의심각도와유의한상관관계 (P<0.05) 를보였다. 그외일반적으로평가시에사용되는 ESS를비롯하여 SSS, ISI, PSQI 에서는유의한상관관계가관찰되지않았다 (Table 2). Table 1. Demographic characteristics of patients. Normal n : 17 Mild OSA n : 25 Moderate OSA n : 32 Severe OSA n : 75 P-value Age,years 48.8±15.3 48.8±14.7 47.3±12.3 45.7±13.2 0.713 Neck Circumference,cm 36.7±4.0 38.0±3.5 38.1±3.2 40.1±3.1 <0.001 Waist Circumference,cm 91.1±9.0 91.5±7.8 89.6±10.2 97.2±8.5 <0.001 BMI 25.2±3.5 26.6±7.0 25.6±3.8 28.3±3.9 0.007 Sleep efficirncy 76.8±25.9 78.4±17.8 77.7±19.1 74.6±15.9 0.755 AHI 2.0±1.5 9.6±2.6 22.8±4.5 58.4±18.2 <0.001 BMI; body mass index, AHI; apnea hypoapnea index, *p<0.05 Table 2. Each sleep scale and questionnaire of OSA patients. Normal n : 17 Mild OSA n : 25 Moderate OSA n : 32 Severe OSA n : 75 P-value SSS 2.8±1.0 2.7±1.1 2.1±1.1 2.5±0.9 0.087 ESS 7.2±4.5 6.2±4.3 6.5±3.5 7.4±3.5 0.493 ISI 12.1±7.0 10.4±6.2 7.6±6.9 8.9±5.5 0.074 PSQI 15.6±6.4 14.8±7.3 10.6±6.2 12.3±5.9 0.059 BDI 37.8±10.2 34.7±10.4 31.6±8.5 30.7±8.0 0.026 Berlin questionnaire 9.9±4.8 12.4±5.7 14.2±5.7 16.4±4.8 <0.001 OSA; obstructive sleep apnea, ESS; Epworth Sleepiness Scale, SSS; Stanford Sleepiness Scale, ISI; Insomnia Severity Index, PSQI; Pittsburgh Sleep Quality Index, *p<0.05 Vol.5, No.2 / December, 2008 91
고찰환자스스로시행할수있는수면척도설문은폐쇄성수면무호흡증환자들에게서그정도를반영하는데수면잠복기검사전 screening 검사로서쉽고간단하여많이사용되고있다. 그러나최근연구에서는불면증이나주간졸리움이폐쇄성수면무호흡증환자들에서항상나타나는것이아니며증상을반영하는데있어그정확도가낮은것으로보고되고있다. 7,9 특히한국에서는폐쇄성수면무호흡증환자의중증도와수면척도간의상관성에대한보고가없기에본연구에서는폐쇄성수면무호흡증환자들을대상으로수면척도설문조사와야간수면다원화검사를실시하여그상관성을알아보고자하였다. 본연구결과, 기존에주로사용되고있는수면척도설문조사중 BDI, Berlin questionaire 를제외하곤전반적으로폐쇄성수면무호흡증환자의중증도에상관없이낮은관련성을보이고있었다. ESS를비롯한 SSS, ISI, PSQI 와같은수면척도검사들이폐쇄성수면무호흡증환자에서 RDI와더연관성이높을것이라는기대와는다른결과룰보였다. 이러한결과는엡워스수면지수가상황에따라서는졸리움을객관적으로반영하지못하다는연구, 13 엡워스수면지수와다중수면잠복기검사사이의연관성이없다는연구 14 그리고폐쇄성수면무호흡증환자들은졸리움을에너지부족, 지침, 피곤등으로증상을호소하는경우가많으며의외로졸리움으로바로표현하는경우는적다는연구 15 들과유사한결과를보였다. 그리고, 환자들이폐쇄성수면무호흡증으로인해나타나는증상을피곤함, 탈진등과같이다른표현으로호소할수있다는점으로미루어수면설문조사에서충분히반영되지못할수있을것으로생각된다. 더불어앞서설명한바와같이아직우리나라에서는표준화되어있지않기에수면설문조사만으로폐쇄성수면무호흡증을판단하는것은그예측도가낮을것으로생각되며, 수면다원화검사와수면설문조사를통해폐쇄성수면무호흡증의중증도를예측할수있는지에대한평가가이루어졌다는데에본연구의의의가있다고생각된다. Roure 등의연구에의하면수면무호흡증환자평가에서는대사상태 (metabolic status), 운동의강도, 우울증및 감정적인스트레스와같은가능한요소들도포함되어야한다고주장하였다. 9 또한주관적인수면척도설문결과와객관적인 AHI 나 RDI 소견이반드시일치하지않는다는연구결과를고려할때폐쇄성수면무호흡증환자의평가에는다양한요소들이영향을미칠수있으리라생각된다. 9 특히폐쇄성수면무호흡증환자들에게서우울증이관련이있다는기존의연구결과와마찬가지로본연구에서도역시한국판 BDI 결과에서수면무호흡증환자들이정상대조군에비해통계적으로유의한결과를보였다. 16,17 이는폐쇄성수면무호흡증이우울증, 불안, 스트레스, 수면위생및건강상태등과복합적으로관련되어나타나기때문일것으로추정된다. 본연구에서는각각의수면척도설문지와폐쇄성수면무호흡증환자군에서의호흡장애지수간의연관성을비교한결과 Berlin questionnaire 와 BDI만이폐쇄성수면무호흡증환자의심각도를평가하는데도움이되는것을관찰할수있었으나이상의결과만으로볼때폐쇄성수면무호흡증환자에있어임상증상만으로수면다원검사에의한수면무호흡증의심한정도를예측하거나, 수면다원검사에의한호흡장애지수로임상증상을예측할수없다는것을알수있었다. 하지만수면클리닉을방문한환자들은비록수면다원검사에서이상소견이보이지않더라도수면과관련된증상을가지고내원하므로수면다원검사에이상이있는사람들과의임상증상의비교는상대적으로차이가적을것으로기대된다. 따라서향후더많은사람들을대상으로주관적인설문척도만으로는수면무호흡증을진단하기보다는수면다원화검사, 다중잠복기검사, 수면각성활동도검사와같은객관적인수면검사들이반드시동반되어추가적인연구가필요할것으로생각된다. REFERRENCE 1. Yun CH. A diagnosis and treatment of obstructive sleep apnea syndrome. J Kor Sleep Research Soc 2004;1:34-40. 2. Bassiri AG, Guilleminault C. Clinical features and evaluation of obstructive sleep apnea-hypopnea syndrome. In: Kryger MH, Roth T, Dement WC. Principles and Practice of Sleep Medicine. 3 rd ed. Philadelphia: Saunders. 2000;869-878. 3. Strollo PJ Jr, Rogers RM. Obstructive sleep apnea. N Engl J Med 92 수면
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