Soonchunhyang Medical Science 18(1):18, June 2012 pissn: 22334289 I eissn: 22334297 ORIGINAL ARTICLE 특수건강진단의직업성천식선별기능강화를위한방안연구 조성용 순천향대학교구미병원직업환경의학과 The Study about the Plans for Consolidating Screening Function of Special Health Examination for Occupational Asthma Seong Yong Cho Department of Occupational and Environmental Medicine, Soonchunhyang University Gumi Hospital, Soonchunhyang University College of Medicine, Gumi, Korea Objective: The aim of this study is to consolidate screening function of special health examination for occupational asthma by investigating the results of respiratory function test as for workers who have been exposed to agents that cause occupational asthma. Methods: To find out cases of occupational asthma, we carried out nonspecific bronchial hyperresponsiveness (NSBH) test, peak expiratory flow rate (PEFR) test in appointed order for asthmasuspected cases among 4,602 workers that had a spirometry as a special health examination from April 2009 to July 2011. And we also performed ttest, oneway ANOVA, and multiple regression analysis to compare and analyse the associations between forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) and duration of exposure, kinds of agents, and number of exposed agents that cause occupational asthma. Results: The case of occupational asthma was not found among 4,602 workers. And the result of a multiple regression analysis show ed that organic compounds were correlated with FEV1/FVC (P= 0.021). However, duration of exposure and number of exposed agents that cause occupational asthma were not associated with FEV1/FVC. Conclusion: For strengthening screening function of special health examination for occupational asthma, we can consider simultaneous operation of NSBH and PEFR, extending the PEFR term from 2 weeks to 4 weeks, thorough history taking on asthma. And as organic compounds may have effect on bronchial obstruction, so we need to concentrate on organic compoundsexposed workers for early screening of occupational asthma. Keywords: Occupational asthma; Respiratory function tests; Screening test 서론직업성천식은작업환경에서분진, 가스, 증기, 흄등에노출되어발생되는기도폐쇄및기도과민성으로정의된다 [1]. 직업성천식을일으키는원인물질로는현재약 200개이상이지목되고있으며 [2], 국가간의차이는있지만, 천식환자의약 2 15% 가직업성천식으 로추정되고있다 [3,4]. 직업성천식으로진단하기위해서는첫째, 천식여부를확인해야하며, 둘째는작업관련성을증명해야한다 [5]. 천식은기침, 천명, 흉부압박감, 호흡곤란등의호흡기증상들과비특이기도과민검사 (nonspecific bronchial hyperresponsiveness, NSBH) 등의검사를통해기도폐쇄또는기도과민성을확인함으로써진단할수있 Correspondence to: Seong Yong Cho Department of Occupational and Environmental Medicine, Soonchunhyang University Gumi Hospital, Soonchunhyang University College of Medicine, 179 1Gongdanro, Gumi 730706, Korea Tel: +82544689432, Fax: +82544689445, Email: predoc97@schmc.ac.kr Received: Feb. 10, 2012 / Accepted after revision: Jun. 8, 2012 2012 Soonchunhyang Medical Research Institute This is an Open Access article distributed under the terms of the Creative Commons Attribution NonCommercial License (http://creativecommons.org/licenses/bync/3.0/). http://jsms.sch.ac.kr 1
Cho SY The Plans for Consolidating Screening Function of Special Health Examination for Occupational Asthma 다. 작업관련성은작업관련증상여부와작업환경을조사하고, 최대호기유속검사 (peak expiratory flow rate, PEFR) 등의객관적인검사를실시함으로써확인할수있다 [3,4,6]. 현재국내에서실시되고있는특수건강진단의경우는총 28종의유해인자에대해서 1차검사에폐활량검사 (spirometry), 흉부X선검사등을실시하고있으며, 이중직업성천식을일으킬수있다고알려진 18종유해인자에대해서는 2차검사에추가적으로 NSBH와 PEFR을실시할수있도록되어있다 [4,710]. 직업성천식은천식증상이없을때는객관적인소견이없는특징들때문에건강한근로자를대상으로하는특수건강진단으로는발견이쉽지않은질병으로 [11,12], 상대적으로병 의원또는대학병원호흡기내과에서발견되는경우가많은것으로추정되고있지만 [13], 직업성천식의규모가어느정도인지도잘파악이안되고있는실정이다 [14]. 현재국내에서운영되고있는직업성천식감시체계나이소이사네이트노출근로자들을대상으로한연구를통해직업성천식사례들이보고되고있으나, 특수건강진단에의한직업성천식진단및판정사례는매우드물다 [12,13,15]. 이에본연구진들은직업성천식선별기능을강화시킴으로써검사초기에직업성천식의심환자들이누락되는것을최소화시키는방안을모색하고자하여, 2009년 4월부터약 27개월간실시한특수건강진단의직업성천식진단과정및사례여부를조사하였다. 또한천식의특징적인소견중의하나인기도폐쇄성과천식유발인자와의관련성을분석함으로써, 천식유발인자에노출된천식의심환자를선별하는데기초적인정보를제공하고자하였다. 대상및방법 1. 연구대상및기간 2009년 4월 20일부터 2011 년 7월 1일까지순천향대학교구미병원직업환경의학과에서실시한특수건강진단수검자중호흡기계유해인자에 1가지이상노출되어폐활량검사를받은근로자를대상으로하였다. 2. 연구방법 1) 특수건강진단폐활량검사관련유해인자분류특수건강진단에서폐활량검사를시행하는호흡기계유해인자분류는총 28종 ( 유기화합물 8종, 금속류 9종, 허가대상물질 3종, 광물성오일 1종, 분진류 6종 ) 이며, 이중 2차검사에서 NSBH와 PEFR을실시할수유해인자는총 18종 ( 유기화합물 8종, 금속류 4 종, 허가대상물질 1종, 광물성오일 1종, 분진류 4종 ) 으로규정되어있다 [10]. 본연구에서는특수건강진단 2차검사에서천식증상과관련하여 NSBH 또는 PEFR을실시할수있도록규정되어있는유해인자를 천식유발인자 로분류하였으며, 총 28종의유해인자중 연구대상자 4,602명이노출된유해인자들을조사하여물리화학적특성별로분류하였다. 2) 폐기능검사폐활량검사는 CPFS/D USB (Medical Graphics Co., St. Paul, MN, USA) 를이용하여검사하였으며, NSBH는 Sensormedics VMAX 22 PFT Spirometer (Sensormedics Co., Yorba Linda, CA, USA) 를사용하였다. NSBH의양성기준은 PC20 16 mg/ml로하였으며, 이검사에서양성인경우에 PEFR을실시하였다 [3]. PEFR은 MPE 7200 MicroPeak Flow Meter (Micro Medical Ltd., Rochester, Kent, UK) 를이용하여근로자가휴일포함하여총 10일동안하루 5회 ( 기상직후, 작업 1시간후, 점심식사전, 작업종료, 취침직전 ) 를측정하였으며, 1회측정시마다 3번이상검사를하여가장높은수치를작성하도록하였다. PFER 실시결과일중변동이근무일중일때가휴무일중일때보다더크거나일중변동값이 20% 이상일때작업관련성이있다고판정하였다 [9]. 각폐기능검사결과의재현성, 적합성여부및결과판정은산업안전보건공단의실무지침들을근거로하였다 [79]. 3) 폐기능환기장애분류폐활량검사에서노력성폐활량 (forced vital capacity, FVC), 1초간노력성호기량 (forced expiratory volume in 1 second, FEV1) 의비정상기준은 80% 미만으로하였으며 [16,17], 일초율 (FEV1/FVC) 은 70% 미만을비정상으로하였다 [1820]. 폐기능환기장애분류는 1) 정상 (FVC 80% and FEV1/FVC 70%), 2) 제한형환기장애 (FVC < 80% and FEV1/FVC 70%), 3) 폐쇄형환기장애 (FVC 80% and FEV1/FVC < 70%), 4) 혼합형환기장애 (FVC < 80% and FEV1/FVC < 70%) 로분류하였다 [18,21]. 연구기간동안 2회이상폐활량검사를실시한경우, 검사결과가모두정상일때는가장최근에실시한검사결과를인용하였으며, 1회라도비정상으로나온경우에는비정상검사결과를인용하였다. 3. 통계분석본연구에서는천식유발인자에대한노출기간, 유해인자개수및종류와기도폐쇄성과의연관성을파악하고자, 기도폐쇄를표시하는지표로사용되는일초율을종속변수로하였으며, 성별, 나이, 흡연여부, 유해인자노출기간, 유해인자종류, 유해인자수를독립변수로하여 t검정 (ttest) 및일원분산분석 (oneway analysis of variance) 을시행하였다. 단변량분석에서유의한변수들과일초율의관계를평가하기위하여다중회귀분석 (multiple regression analysis) 을시행하였다. 통계분석은 SPSS ver. 17.0 (SPSS Inc., Chicago, IL, USA) 프로그램을사용하였으며, 신뢰수준은 95%, P값은 0.05 미만을통계학적으로유의한것으로판단하였다. 2 http://jsms.sch.ac.kr Soonchunhyang Medical Science 18(1):18
특수건강진단의직업성천식선별기능강화방안 조성용 1. 특수건강진단결과분석 결과 폐활량검사상정상 4,148 명 (90.1%), 제한형환기장애 367 명 (8.0%), 폐쇄형환기장애 78 명 (1.7%), 혼합형환기장애 9 명 (0.2%) 으로조사 되었다. 정상군 (4,148 명 ) 중 10 명의경우, 문진시천명 (1 명 ), 업무시 호흡곤란및기침 (5 명 ), 천식과거력 (2 명 ), 평상시심한기침및가래 증상 (2 명 ) 소견을보여 NSBH 를실시하였다. 10 명중 2 명은양성이 었으며, 8 명은음성이었다. NSBH 에서양성으로나온 2 명중 1 명은 작업관련하여호흡기증상이없어서 PEFR 을실시하지않았으며, 나머지 1 명은 PEFR 결과작업관련성이없었다. 제한형환기장애 를보인 387 명중평상시기침및호흡곤란이심하거나, 작업중호 흡곤란과기침및가래증상을호소하는인원등총 14 명에대해 NSBH 를실시한결과총 14 명중 12 명이음성이었으며, 2 명이양성 으로나왔다. 양성으로판정된 2 명중 1 명은 PEFR 을실시한결과, 작업관련성이없었으며, 나머지 1 명은퇴사로인해 PEFR 을실시하 지못하였다. 폐쇄형환기장애를보인 78 명중 35 명이 NSBH 를실 시하였는데, 이 35 명중 18 명이음성으로조사되었다. NSBH 에서 양성을보인 17 명중문진상작업관련호흡기증상을보이지않았 던 3 명과퇴사를한 1 명을제외한 13 명에대해서 PEFR 을실시하였 지만, 역시작업관련성이없었다. 폐쇄형환기장애를보인 78 명중 NSBH 를실시하지않은 43 명은청진상정상소견및평소호흡기 증상이없었기때문에 NSBH 및 PEFR 을실시하지않았으며, 혼합 형환기장애를보인 9 명의경우도작업관련하여특이호흡기증상 을보이지않아 NSBH 및 PEFR 을실시하지않았다 (Fig. 1). + (n=2) PEFR Non OA Normal (n=4,148) (n=4,138) NSBH (n=10) (n=8) Currently no asthma Restrictive (n=367) PEFR Non OA NSBH (n=14) History taking physical examination (n=353) + (n=2) (n=12) Spirometry (n=4,602) Currently no asthma + (n=17) Fig. 1. Algorithm for evaluation of a worker suspected of occupational asthma (OA). NSBH, nonspecific bronchial hyperresponsiveness; PEFR, peak expiratory flow rate. (n=4) PEFR (n=13) (n=13) Non OA Obstructive (n=78) NSBH (n=35) (n=18) Currently no asthma (n=43) Combined (n=9) Suspected non OA or the other obstructive lung disease 2. 호흡기특수건강진단유해인자분류 특수건강진단 1 차검사중폐활량검사를실시해야하는호흡기 계유해인자개수는총 28 종이지만 [4], 본연구에참여한근로자는 21 종의유해인자에노출되고있었다. 21 종의유해인자중천식유 발인자는 14 개종 ( 분진류 4 종, 금속류 4 종, 유기화합물 5 종, 광물성 오일 1 종 ) 으로조사되었다. 4,602 명의근로자가 21 종의유해인자들 에대해실시한검진건수는총 5,829 건으로근로자 1 인당약 1.26 종의유해인자에노출되는것으로조사되었고, 유해인자별노출빈 도는광물성분진이 1,915 건 (32.8%) 으로가장많았고, 주석과그무 기화합물 817 건 (14.0%), 미네랄오일미스트 666 건 (11.4%) 순이었다. 1 종의유해인자에만노출되는근로자가 3,701 명 (80.4%) 으로가장 Table 1. Classification of agents that have to carry out spirometry on 1st special health examination Variables No. of subjects (%) Classification of hazard chemicals (n= 5,829) Dusts Grain a) 2 (0.03) Mineral 1,915 (32.85) Cotton a) 69 (1.18) Wood a) 35 (0.60) Welding fumes a) 334 (5.73) Fibrous glass 120 (2.06) Metals Nikel and compounds, as Ni a) 182 (3.12) Iron oxide dust and fume, as Fe 509 (8.73) Antimony and compounds, as Sb 89 (1.53) Aluminum and compounds, as Al a) 554 (9.50) Tin and inorganic compounds, as Sn 817 (14.02) Cobalt dust and fume, as Co a) 62 (1.06) Chromium and compounds, as Cr a) 247 (4.24) Tungsten and compounds, as W 16 (0.27) Organic compounds Diethylenetriamine a) 4 (0.07) Maleic anhydride a) 16 (0.27) Methylene bisphenyl isocyanate a) 71 (1.22) Hexamethylene diisocyanate a) 10 (0.17) Toluene 2,4diisocyanate a) 15 (0.26) Metal working fluids Oil mist, mineral a) 666 (11.43) Chemicals for authorisation Asbestos 96 (1.65) N o. of agent that have to carry out spirometry on 1st special health examinations (n= 4,602) 1 3,701 (80.42) 2 682 (14.82) 3 166 (3.61) 4 53 (1.15) a) Agents that cause occupational asthma. Soonchunhyang Medical Science 18(1):18 http://jsms.sch.ac.kr 3
Cho SY The Plans for Consolidating Screening Function of Special Health Examination for Occupational Asthma 많았으며, 4개이상의인자에노출된근로자도 53명 (1.15%) 이나되었다 (Table 1). 3. 일초율과성별, 나이, 흡연, 유해인자노출기간, 개수및종류와의연관성남성 (4,032 명, 87.6%) 과여성 (570 명, 12.4%) 의일초율의경우 83.05 ± 6.63과 86.39± 6.19로남성이유의하게낮았으며, 연령대로는 50 대 (372 명, 8.1%) 가일초율 78.23±7.08 로가장낮게조사되었다. 흡연의경우흡연자 (2,605명, 56.6%) 의일초율이 83.00± 6.80, 비흡연자 (1,461 명, 31.7%) 84.79± 6.35, 과거흡연자 (536 명, 11.6%) 82.17± 6.34로흡연자가가장낮게조사되었다. 천식유발인자노출기간에따른일초율은 1 12 개월미만동안노출된경우가 83.90± 6.57, 48 개월이상 (658 명, 14.3%) 82.26± 6.31로조사되었는데, 노출기간에따라일초율이유의한차이를보였다. 작업시근로자가노출되는천식유발인자개수의경우는노출이안된군 (2,660명, 57.8%) 이 83.62± 6.80, 3종이상 (66명, 1.4%) 은 80.77± 6.86으로 3종이상군에서가장낮게조사되었다. 천식유발인자들을종류별로분류하였을경우, 광물성오일의일초율이 84.56± 6.01로가장높았으며, 유기화합물군이 80.99 ± 6.72 로가장낮게조사되었다 (Table 2). Table 2. FEV1/FVC of the study subjects by general and work related characteristics Variables Total (n= 4,602) FEV1/FVC Pvalue Gender Male 4,032 (87.6) 83.05± 6.63 < 0.001 a) Female 570 (12.4) 86.39± 6.19 Age 20 70 (1.5) 88.13± 6.17 < 0.001 b) 20 29 1,473 (32.0) 85.96± 6.22 30 39 1,553 (33.3) 83.47± 6.26 40 49 1,154 (25.1) 81.68± 6.03 50 372 (8.1) 78.23± 7.08 Cigarette smoking Nonsmoker 1,461 (31.7) 84.79± 6.35 < 0.001 b) Exsmoker 536 (11.6) 82.17± 6.34 Current smoker 2,605 (56.6) 83.00± 6.80 Exposed duration to agents that cause OA (mo) 0 2,660 (57.8) 83.62± 6.80 < 0.001 b) 1 12 670 (14.6) 83.90± 6.57 12 24 297 (6.5) 83.80± 6.29 24 36 182 (4.0) 83.51± 6.54 36 48 135 (2.9) 83.50± 6.69 48 658 (14.3) 82.26± 6.31 No. of exposed agents that cause OA 0 2,660 (57.8) 83.62± 6.80 0.001 b) 1 1,727 (37.5) 83.26± 6.48 2 149 (3.2) 84.46± 5.97 3 66 (1.4) 80.77± 6.86 Classification of agents that cause OA Agents except that related OA 2,660 (57.8) 83.62± 6.80 < 0.001 b) Dusts c) 369 (8.0) 81.65± 6.34 Metals d) 751 (16.3) 83.21± 6.57 Metal working fluids e) 655 (14.2) 84.56± 6.01 Organic compounds f) 77 (1.7) 80.99± 6.72 Coexposure with different goup g) 90 (2.0) 82.80± 6.67 Values are presented as mean± SD or number (%). FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; OA, occupational asthma. a) Performed by ttest. b) Performed by oneway ANOVA. c) Grain, cotton, wood, and welding fumes. d) Ni, Al, Co, and Cr. e) Oil mist and mineral. f) Diethylenetriamine, maleic anhydride, hexamethylene diisocyanate, toluene 2, and 4diisocyanate. g) (Dusts+metals), (dusts+oil mist, mineral), (metals+oil mist, mineral), (dusts+metals+oil mist, mineral). 4 http://jsms.sch.ac.kr Soonchunhyang Medical Science 18(1):18
특수건강진단의직업성천식선별기능강화방안 조성용 Table 3. A multiple linear regression analysis of forced expiratory volume in one second/forced vital capacity including gender, age, smoking status, duration of exposure, number of agents, kinds of agents that cause OA as independent variables Variables β SE (β) tstat Pvalue a) Gender (ref: male) Female 3.465 0.300 11.555 < 0.001 Age (yr) 0.267 0.011 25.292 < 0.001 Smoking (ref: nonsmoker b) ) Smoker 0.886 0.196 4.521 < 0.001 Duration of exposure (mo) 0.000 0.001 0.557 0.577 No. of exposed agents (ref: 2) Above 2 (> 2) 0.154 0.530 0.291 0.771 Kind of agents (ref: agents except that related OA) Dusts c) 0.345 0.346 0.996 0.319 Metals d) 0.404 0.264 1.534 0.125 Metal working fluids e) 0.439 0.268 1.637 0.102 Organic compounds f) 1.662 0.721 2.303 0.021 Coexposure with different goup g) 0.080 0.780 0.103 0.918 OA, occupational asthma. a) Performed by multiple linear regression analysisttest. b) Nonsmoker and exsmoker. c) Grain, cotton, wood, welding fumes. d) Ni, Al, Co, Cr. e) Oil mist, mineral. f) Diethylenetriamine, maleic anhydride, hexamethylene diisocyanate, toluene 2,4diisocyanate. g) (Dusts+metals), (dusts+oil mist, mineral), (metals+oil mist, mineral), (dusts+metals+oil mist, mineral). 4. 천식유발인자노출기간, 개수및종류가일초율에미치는영향분석폐활량검사의일초율을종속변수로한다중회귀분석에서는단변량분석에서유의한변수로조사되었던성별, 나이, 흡연여부는일초율과유의한연관성을보였다. 작업관련특성중에서는천식유발인자에대한노출기간및유해인자개수는유의한연관성이없었지만, 유해인자종류에서유기화합물군만이천식유발인자에노출된적이없는군에비해서일초율이유의하게낮게나왔다 (Table 3). 고찰현재국내에서진행되고있는직업성천식감시체계를통해보고된직업성천식사례의경우, 전국적으로 1998년에는 33건이보고되었으며, 2004년부터 2009년에는매년 28 54건정도가보고되었다 [12,14]. 2001년부터약 1년간구미지역내에서실시된감시체계에서도 16건의직업성천식이보고되었으며 [15], 1996년도부터약 2년간인천지역한대학병원에내원하였던천식환자 411명을대상으로한연구에서는직업성천식이 16명이보고되었다 [13]. 하지만이들사례대부분이알레르기 호흡기내과전문의에의한보고가대부분이었으며, 특수건강진단에의해서진단및보고된사례는한건도없었다 [1215]. 본연구에서도 27개월간 4,602명을대상으로시행된특수건강검진결과를조사하였지만, 직업성천식사례가없었다. 특수건강진단의대상이평상시천식관련증상들이없는건강한근로자들이기때문에천식진단자체가쉽지않은근원적인요인은있지만 [11,12], 특수건강진단이직업성질환의조기선별및관 리에있어매우중요한역할을담당하고있기때문에, 검진체계내에서직업성천식의선별기능을강화하기위한노력은지속적으로이루어져야할것으로생각된다. 천식의진단과정에있어서는연구자마다약간의차이를보이고있지만, 큰틀에서보았을경우 1단계설문, 이학적검사및폐활량검사, 2단계 NSBH, 피부단자시험 (skin prick test), 특이 IgE 항체검사 (specific IgE antibody test), 3단계 PEFR, 특이적기관지유발검사 (specific inhalation test), 4단계는작업장유발검사 (workplace challenge test) 순으로실시되고있다 [3,6,22]. 피부단자검사와특이 IgE 항체검사는고분자량물질이직업성천식과관련이있을때높은특이도와민감도를가지는검사방법으로, 피부검사가양성인경우또는특이항체가존재할경우에는노출인자에대한감작 (sensitization) 상태를의미하므로 [3], 이후직업성천식의발생여부에대한면밀한관찰이권장된다 [4]. 하지만특이항체검사및피부단자시험은표준검사시료 (reagents) 와표준항원 (antigen) 이부족하여쉽게실시하지못한다는제한점이있으며 [2,23], 또한이소시아네이트등과같은저분자량물질의경우에는 IgE나 IgG 의존성기전이일관성있게나타나지않기때문에결과해석에많은어려움이있다 [2,4]. 특이적기관지유발검사는직업성천식진단에서황금기준 (gold standard) 인검사방법으로검사에서양성이면직업성천식으로진단이가능하다. 하지만음성인경우에는검사실내노출방법과작업장의노출형태가차이가있는경우, 근로자가작업을오랫동안하지않은경우등여러원인에의한위음성을배제할수없기때문에, 검사결과에서의음성이직업성천식이아님을의미하지않는다 [3,22]. 또한비용이비싸고, 시간 Soonchunhyang Medical Science 18(1):18 http://jsms.sch.ac.kr 5
Cho SY The Plans for Consolidating Screening Function of Special Health Examination for Occupational Asthma 이많이소요되며, 검사도중에피검사자의건강상태가급격히악화될수있기때문에, 장비및인력이구비되어있는기관에서만실시되고있다 [3,6,22]. ChanYeung [3] 은피부단자검사및특이 IgE 검사를실시하지못하는경우에는 NSBH를실시해야하며, 특이적기관지유발검사를시행하지못하는경우에는 PEFR를실시해야한다고하였는데, 특수건강진단에서피부단자검사와특이 IgE 검사, 특이적기관지유발검사의경우근로자에게일괄적으로실시하는선별검사로적용하기는힘들며, 직업성천식확진여부를최종적으로판단하고자할때에추가적으로실시하는것이적절하다고판단된다. 본연구에서는 NSBH의양성기준을 PC20 16 mg/ml로하였으며, 이검사에서양성인경우에 PEFR을실시하였다. PEFR가음성이면 PEFR의특이도의검사특이도가 88 100% 임을감안하여 [24,25], 직업성천식을배제하였으며 [3], PEFR이양성이면추가적으로특이적기관지유발검사또는작업장유발검사등을실시하기로하였다. 본연구에서는직업성천식사례가없었는데, 직업성천식근로자가호흡기증상과관련하여오랫동안근무를하지않은상태이거나, 기관지확장제또는항히스타민제제등의약물을복용한경우 [22] 등으로인해폐활량검사또는 NSBH에서정상으로나왔을경우를배제할수없다. 이에대해추후에는문진단계에서부터천식관련과거력및이학적검사등을철저히해야할것이다. 증상설문 (respiratory questionnaires) 은직업성천식진단에대한특이도가 14 32% 로매우낮은편이지만, 민감도의경우에는약 87 95% 로높기때문에 [2,26], 폐활량검사와함께직업성천식의심환자의 1차선별에많은도움이될것으로판단된다. 특히고분자량물질에의한직업성천식의경우에는천명 (wheezing), 코와눈주위가려움증 (nasal and ocular itching) 증상이직업성천식이아닌경우에비하여유의하게많았다는연구가있었는데 [27], 청진소견뿐만아니라코와눈관련증상도같이확인하는것이천식조기선별에도움이될수있을것이라판단된다. PEFR은직업성천식진단에대한민감도와특이도가 82% 와 88% [24], 73%, 100% [27] 로, 직업성천식진단에매우유용하게검사이다. 구매비용이저렴하며, 근로자가손쉽게사용할수있다는장점 [23,28] 이있기때문에, 본연구처럼 NSBH에양성으로나온근로자에대해서만 PEFR을실시하는것보다는 NSBH와 PEFR을동시에실시하는것을고려해볼수있을것이다. 또한 PEFR 검사기간을 2주실시한것과 4주실시한것을비교하여민감도와특이도를조사한연구에의하면, 민감도와특이도가각각 70.0%, 82.4% 에서 81.8%, 93.8% 로증가하였는데 [29], PEFR을 4주동안실시한다면직업성천식진단에도움이될수있을것으로판단된다. PEFR의경우, 검사전검사방법에대해근로자교육을하지만, 근로자의노력에많이의존하여오차가있을수있기때문에 [28], 검사실시전사용방법에대해서철저한사전교육을실시한다면보다정확하고신뢰성있는측정값을얻을 수있을것이다. 또다른방안으로 NSBH의양성판정기준을 PC20 16 mg/ml에서 PC20 25 mg/ml로하여민감도를높이는것도고려해볼수있겠지만, 천식군의진단에대해 receiver operating characteristic curve 분석을시행한결과가장정확도를높일수있는기준치는 15.4 mg/ml로보고된연구가있는것처럼 [30], NSBH 의양성판정기준은기존처럼 PC20 16 mg/ml를사용하는것이적절하다고판단된다. 본연구에서는천식의특징적인소견중의하나인기도폐쇄성과천식유발인자와의관련성을파악하고자하여천식유발인자에대한노출기간, 유해인자개수및종류를독립변수로, 일초율을종속변수로하여분석을실시하였다, 일초율은기도폐쇄를표시하는지표로이용이되는데 [16,19], 본연구분석결과일초율이저연령층보다고연령층에서, 비흡연자보다는흡연자에서, 여성보다는남성에서일초율이유의하게감소한결과를보였다. 연령과일초율의연관성 [17,3133] 과흡연과일초율과의연관성 [17,31] 의경우기존의연구와일치하고있으며, 성별의경우도일초율과의유의한관계가없다는연구 [31] 도있지만, 다른다수의연구에서는여성에비해서남성이일초율이낮은것으로조사되었다 [20,32,33]. 천식유발인자의경우에는유해인자에대한노출강도가천식의발생에매우중요한인자로작용하지만 [2,6], 저농도의노출에대한감작의위험성에대해서는아직객관적인근거가부족한실정이다 [2]. 이소시아네이트의노출에대한감작은짧은시간동안의고농도의노출에의해서생긴다고주장한연구도있지만 [34], 근로자 140명을대상으로직업성천식을조사한연구 [35] 에서는작업환경측정결과모두기준치미만이었지만, 직업성천식사례가 3명이발견되었다. 본연구에서는유기화합물군이천식유발인자에노출된적이없는군에비해일초율이유의하게저하된결과를보였다. 본연구의유기화합물군에는이소시아네이트류 ( 메틸렌비스페닐이소시아네이트, 헥사메틸렌디이소시아네이트, 톨루엔 2,4디이소시아네이트 ), 디에틸렌트리아민, 말레익언하이드라이드가포함되어있었는데, 해당유해인자에대한노출작업을거의하지않아작업환경측정에서빠진경우를제외하고는그외측정결과는모두노출허용기준미만이었다. 이소시아네이트의노출허용기준미만의농도에서도직업성천식사례가발견된연구 [35] 를근거로본다면, 이소시아네이트의저농도노출에도기관지폐쇄성에영향을준다고추정할수있다. 반면에말레익언하이드라이드와디에틸렌트리아민은천식과관련된연구가매우드물뿐만아니라, 말레익언하이드라이드노출에의한직업성천식사례도노출허용기준을초과된상태에서진단된것이었으며 [36], 디에틸렌트리아민에의한천식사례도작업환경측정을실시하지않았으므로 [37], 이들물질에대한노출과기도폐쇄성과의연관성에대해서는평가하기힘들다. 추후말레익언하이드라이드와디에틸렌트리아민에대한저농도노출과기도폐쇄성과의연관성에대해서는추가적인연구가필요할것으로 6 http://jsms.sch.ac.kr Soonchunhyang Medical Science 18(1):18
특수건강진단의직업성천식선별기능강화방안 조성용 생각된다. 본연구의제한점으로는첫째, 개인별천식유발인자의노출정도 를파악하지못하여노출량과기도반응과의관계를평가할수없 었으며, 둘째, 특수건강진단상의호흡기계유해인자가실제로근로 자가많이취급하고노출되는물질로간주하기는어렵다는점이며, 셋째, 흉부질환자, 호흡기계관련약물복용여부를정확히배제하 지못한점, 마지막으로천식소견자의퇴사, 부서전환등으로인한 건강근로자효과를배제하지못하였다는것이다. 하지만다른천 식유발인자군보다도유기화합물군에노출된근로자에게서유의 하게일초율이감소된것을근거로, 추후직업성천식의심환자선 별과정에서도움이될수있는기초적인정보를제공하였다는점에 서의의가있다고하겠다. 직업성천식은소음성난청, 진폐증과달리조기진단이매우어 려운질병이지만, 치료가조기에이루어진다면천식소견이정상화 될수있다는점에서예방및조기선별이매우중요하다고할수있 겠다. 본연구에서는직업성천식사례가없었지만, 특수건강검진 실시중직업성천식에대한문진을철저히하고, 천식의심환자들 에대해 NSBH 와 PEFR 을동시에실시하거나, PEFR 검사기간을연 장하는방법을강구함으로써직업성천식환자들이누락되지않 고, 조기에선별될수있도록해야할것이다. 또한이소시아네이트 등의유기화합물에노출되는근로자에대해서는천식관련호흡기 증상여부및폐기능검사결과들을더욱주의깊게살펴보면서, 직 업성천식조기선별에많은노력을기울여야할것이다. REFERENCES 1. Brooks SM, Truncale T, McCluskey J. Occupational and environmental asthma. In: Rom WN, Markowitz SB, editors. Environmental and occupational medicine. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2007. p. 41863. 2. Mapp CE, Boschetto P, Maestrelli P, Fabbri LM. Occupational asthma. 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