Unexpected Natural Death among Korean Workers
Shared by: eot15664
Journal of J Occup Health 1999; 41: 238–243 Occupational Health Unexpected Natural Death among Korean Workers Jungsun PARK1, Young-Sook CHO1, Kwan-Hyung YI1, Kyung-Yong RHEE1, Yangho KIM2 and Young-Hahn MOON1 1 Industrial Safety and Health Research Institute, Korea Industrial Safety Corporation (KISCO) 2 Department of Occupational and Environmental Medicine, Ulsan University Hospital Abstract: Unexpected Natural Death among Korean unexpected death in a person who had been suffering Workers: Jungsun PARK, et al. Industrial Safety and from an aggravated preexisting condition such as Health Research Institute, Korea Industrial Safety hypertensive or arteriosclerotic diseases. The Korean Corporation—Even though workers’ deaths can be government has compensated the cases of cerebrovascular compensated for in Korea if work stress is substantiated disease and cardiovascular disease due to overwork or as a cause, neither a definition nor a measure has been occupational stress, but neither definition nor measure officially provided to verify occupational stress or overwork. This study was carried out to identify has been officially provided to verify occupational stress epidemiological characteristics and components of or overwork, so that the prevention of, as well as work stress associated with workers’ death. All the compensation for workers’ occupational stress-related records of claims for compensation during 1994–1995 cardiovascular attacks, cannot be carried out efficiently. were reviewed to select only the cases of natural death. Until now few epidemiological, analytical studies on A descriptive study on the characteristics of workers’ sudden unexpected death in Korea have been carried out natural death and a matched case-control study on on the working population; so we started our research to stress components were carried out. Cerebrovascular get an overview of unexpected natural death among accidents was the commonest cause of death (47.3%) Korean workers employed in workplaces with five or in claims for compensation due to work stress, and more employees. The objectives of this study were 1) to coronary artery diseases took second place (29.9%). describe the epidemiological characteristics of those who Sudden death occurring within 24 h after the attack comprised about 1/2 of the total cases. The attack claimed compensation for unexpected natural death; 2) took place most frequently at the workplace and most to identify components of work-related stress associated often during work. When work stress was classified with workers’ death; and 3) to contribute to the prevention and observed in four categories: sudden physical of unexpected death among middle-aged workers. exertion, sudden psychologic excitement, prolongation of work time, and change in responsibility, only physical Methods exertion within 24 h before the onset of symptoms Claim System in Korea proved to be significantly associated with workers’ The Industrial Accident Compensation Insurance Law unexpected natural death. was enacted in 1963 to provide necessary insurance (J Occup Health 1999; 41: 238–243) benefits to injured workers and also give them prompt and fair protection against injury, disease, disability and Key words: Sudden death, Unexpected natural death, Karoshi, Workers’ compensation, Work stress death. The insurance would grant short or long-term benefits, to promote the rehabilitation of workers who Recently, unexpected natural death has become the suffer injury or disease resulting from the employment leading cause of workers’ compensated work-related and to assist the injured workers and their families, and death in Korea. It is generally considered that thereby to promote the welfare of workers. The insurance cardiovascular disorder is the commonest cause of sudden program is administered by the Ministry of Labor and all unexpected death1). Occupational stress can cause sudden enterprises which fit the governmental criteria with some exceptions are required to join this program. An exception Received Apr 30, 1999; Accepted July 9, 1999 is firms which employ less than five workers2). When a Correspondence to: J. Park, Industrial Health Research Institute, worker dies of work-related injury or disease, his or her KISCO, 34-6 Kusan-Dong, Pupyeong-Ku, Inchon 403-711, South family can put in a claim for workers’ compensation Korea arbitrarily to the local office of the Korean Labor Welfare Jungsun PARK, et al.: Unexpected Natural Death among Korean Workers 239 Corporation under the Ministry of Labor. A matched Case-Control Study We tried to find why some workers died unexpectedly, Descriptive Epidemiologic Study but others are still alive in spite of working in the same We defined ‘unexpected natural death’ as an workplace. So we carried out a matched case-control study unaccidental death occurring without warning in a person on the work-related stress component. The number of who had had no restrictions on his daily working activities matched samples from each provincial area were prior to the onset of symptoms. Warning in this setting determined based upon the number of claimed cases in means severe subjective symptoms or objective signs, each provincial area. First of all, case samples in each which could have made him or her see the doctor. provincial area were selected randomly with a proportional Unexpected natural death is unrelated to the time from the sampling rate of 10% by area and industry, the process of onset of disease to death, which time mainly depends on which included the making of lists of random sample various factors such as appropriate first aid measures, the numbers. A matched control for each of the cases was referral system, and level of care in emergency medicine selected according to sex and age (equal or with a difference in cerebro- and cardiovascular diseases. We therefore of less than 5 yr) from workers in the same workplace adopted the term ‘unexpected natural death’ even though (individual 1:1 matching), but not matched for other factors sudden death is a world standard technical term well such as smoking or alcohol consumption. defined as internal death within 24 h from the onset of The selection of each control was then conducted under the event3) and generally accepted and used throughout clear instructions. the world. Sudden death is included in unexpected natural Face-to-face interviews for control group lasted from death not only limited to 24 h after the attack. 20 to 30 min. The interview was conducted in a standard Firstly, all the records of claims for workers’ manner by 4 well trained interviewers. Interviews were compensation during 1994–1995 were reviewed to select periodically monitored for quality control. The only ‘natural death’ with the criteria for internal death, questionnaire included items about demographic and to select only ‘unexpected death’ with the criteria for characteristics (age, sex, marital status, education), warning. We then carried out a descriptive study on the information on physical examination (body weight, characteristics of workers’ ‘unexpected natural death’ height, blood pressure), lifestyle (alcohol consumption, based on information from the records of compensation smoking habit, physical exercise), and the working claims such as death certificates, application forms for conditions (occupation, shiftwork, heavy physical compensation, investigation records of death due to activities or emotional stress related to the worker’s duties industrial accidents, and their past working records, etc. on the survey day, change of work load within a week Claimed cases of unexpected natural death therefore before the survey day, change of work content within a included not only all of the official registered month before the survey day). compensated cases, but also uncompensated cases. McNemar test was performed for matched-pair We prepared a questionnaire of our own and included analysis. in if the contents of records of compensation claims. It included items about demographic characteristics (age, Results sex, marital status, education), information on the attack The sex and age distribution of the death cases claimed (the time and place of the attack, symptoms of the attack, during 1994–1995, the 2 yr of observation, are given in time of death, place of death, and cause of death, etc.), Table 1. The cases claimed were for 812 males (90.8%) information from physical examination (body weight, height, blood pressure, health problems), lifestyle (alcohol consumption, smoking habit, physical exercise), and the Table 1. Sex and age distribution of the working conditions (occupation, shift work). We death cases especially tried to get information about the working Demographic No. of Cases (%) conditions which caused the attack through all available Characteristics documents such as sudden heavy physical activity related to work and which preceded the attack within 24 h, sudden Sex Male 812 ( 90.8) severe emotional stress related to work and which Female 82 ( 9.2) preceded the attack within 24 h, change of work load Total 894 (100.0) which preceded the attack within a week, and change of Age 20–29 41 ( 4.6) work content which preceded the attack within a month. 30–39 146 ( 16.3) The underlying causes and the immediate causes of 40–49 274 ( 30.6) death of all claimed cases were reviewed and corrected 50–59 307 ( 34.4) where the underlying causes and the immediate causes 60 over 126 ( 14.1) of death were reversed by two medical doctors. Total 894 (100.0) 240 J Occup Health, Vol. 41, 1999 Table 2. Industry and occupation distribution of the death cases Industry and Occupation No. of Cases (A) No. of Workers (B) A/B × 100,000 Industry Mining and Quarrying 7 40,308 17.37 Manufacturing 314 3,084,827 10.18 Electricity/Gas 14 53,674 26.08 Water supply Construction 156 1,978,629 7.88 Transportation/ 128 641,032 20.00 Storage Communication Other Community/ 187 1,452,284 12.88 Social and Personal Service Activities Total 806 7,250,754*1) 1.12 Occupation Professional and 29 529,332 5.48 Technological Workers Clerical and related 162 1,655,793 9.78 Workers Sales Workers 17 102,396 16.60 Service Workers 169 280,972 60.15 Production & related 431 1,964,016 21.94 Workers/Transport Equipment Operators/Laborers Others 4 2,479 161.36 Total 812 4,534,988*2) 17.91 Source: *1) Total workers employed in workplaces with five or more employees by industry; Ministry of Labour Report on Establishment Labour Conditions Survey, 1995. *2) Total workers employed in workplaces with 10 or more employees by industry; Ministry of Labour Report on Wage Strucuture Survey, 1995. and 82 females (9.2%). The percentage distributions by Table 3. Daily activity at the time when the age groups of 50–59, 40–49, 30–39, above 60, and 20– attack occurred 29, was 34.4%, 30.6%, 16.3%, 14.1%, and 4.6%, respectively. Men in their forties and fifties were therefore Situation No. of cases (%) predominant. At work 197 ( 58.9) Table 2 shows industry and occupation distribution of Taking a rest 47 ( 14.1) the death cases claimed during 1994–1995. According Moving from place to place 30 ( 9.0) to industrial classification, the proportion among total Sleeping at night 25 ( 7.5) claimed cases was high for the manufacturing industry, Taking a bath 12 ( 3.6) but the incidence rate was highest for the transportation/ Having a meal 8 ( 2.4) storage/communication industry. According to Physical exercise 4 ( 1.2) occupational classification, the proportion among total While in the lavatory 3 ( 0.9) claimed cases was high for production and related Others 8 ( 2.4) workers/transport equipment operators/laborers, but the Total 481 (100.0) incidence rate was highest for service workers. The attack causing unexpected natural death took place at the workplace (70.9%). As shown in Table 3, daily Jungsun PARK, et al.: Unexpected Natural Death among Korean Workers 241 Table 4. The cause of death Table 5. Time lapse between initial attack and death Cause of death No. of cases (%) Time lag No. of cases (%) Cardiovascular diseases 427 ( 47.3) Ischemic heart diseases 270 ( 29.9) Less than 1 h 261 ( 28) Unknown sudden death 157 ( 17.4) 1–24 h 215 ( 23) Others 43 ( 4.8) 1 day–1 week 191 ( 20) Unclassifiable 6 ( 0.7) More than 1 week 194 ( 21) Total 903 (100.0) Unknown 74 ( 8) Total 935 (100) Table 6. The distribution of 477 death cases by the cause of death and age group unit: person (%) Age Cerebrovascular Ischemic heart Unknown Others Total diseases diseases sudden death 20–29 4 (19.0) 6 (28.6) 9 (42.9) 2 (9.5) 21 (100.0) 30–39 36 (48.0) 17 (22.7) 17 (22.7) 5 (6.4) 75 (100.0) 40–49 65 (46.4) 41 (29.3) 24 (17.1) 10 (7.1) 140 (100.0) 50–59 76 (43.2) 73 (41.5) 21 (11.9) 6 (3.4) 176 (100.0) 60–69 29 (44.6) 25 (38.5) 9 (13.8) 2 (3.1) 65 (100.0) Total 210 (44.0) 162 (34.0) 80 (16.8) 25 (5.2) 477 (100.0) activities at the time when the attacks occurred are most of work load, and change of work content. frequently at work (58.9%), and then taking a bath Sudden physical exertion within 24 h before the attack (14.1%), moving from place to place (9.0%), sleeping at was high significantly associated with unexpected natural night (7.5%), in that order. death. And sudden emotional excitement within 24 h As Table 4 shows, the major cause of death in the 903 before the attack was not associated with unexpected cases was cerebrovascular disease (47.3%) and then natural death. Mental stress due to change in work load ischemic heart disease (29.9%). within a week before the attack was less significantly Table 5 shows the time lapse between initial attack associated with unexpected natural death. And mental and death. Among claimed cases due to unexpected stress due to a change in work content within a month natural death, sudden deaths within 24 h of the attack before the attack was significantly associated with comprised 51%. This figure can be divided into 28% for unexpected natural death. deaths within an hour of an attack and 23% for the rest. The peak time of attacks was noon to 4:00 P.M., and Discussion then 8:00 A.M. to noon. Attacks were rare between Of the relationships between occupational stress and midnight and 4:00 A.M. Unexpected natural death tended cardiovascular diseases, Uehata suggested in his case to occur more on Wednesday or Friday, and less on study that the cases of cardiovascular attack among Thursday, Saturday, or Sunday. The peak month for middle-aged workers who claimed workers’ attacks was September, followed by February and compensation mostly consisted of male workers who October. On the other hand, the incidence of attacks was worked for long hours and had other stressful overload lowest in January. and these working situations aggravated their unhealthy Table 6 shows the cause of death by age group. The life habits, resulting in the attacks triggered by minor proportion of cerebrovascular accidents tended to increase work-related troubles or events4). Cooper also suggested with age. And the proportion of unknown sudden deaths in his review that various types of stressors at work, such tended to occur more amongst the lower age groups. as quantitative and qualitative overload, role ambiguity Table 7 summarize the matched comparison of or conflict, over- or under- promotion, and impact of poor unexpected natural death cases and living controls with relationships with reference to these stressors were regard to the experience of various kinds of work-related associated with heart diseases 5). On the other hand, stresses. Work-related stress was divided into sudden Karasek suggested that high psychological work demands physical exertion, sudden emotional excitement, change and low decision latitude on the job may be associated 242 J Occup Health, Vol. 41, 1999 Table 7. Matched comparison of experience of work-related stress in cases and can be a risk factor for unexpected controls: McNemar Test natural death in the present study is also seen in other papers9, 10). By Case Sudden heavy physical activity1) p-value occupation, the incidence rate was Have Not have Total highest for service workers. Have 0 7 0 A large proportion of Control Not have 10 78 88 8.10 0.0020 unexpected natural deaths have Total 10 78 88 been attributed to coronary artery disease (mostly atherosclerotic ischemic heart disease) among Case Sudden severe emotional stress2) p-value males 30 and older1), but Uehata Have Not have Total reported that among 203 Karoshi Have 0 1 1 consultation cases collected for Control Not have 4 83 87 0.80 0.3750 sixteen years from 1974 to 1990, Total 4 84 88 two thirds were strokes including subarachnoidal bleeding, cerebral bleeding and cerebral infarction. Case Latest change in work load3) p-value He also reported that the Have Not have Total proportion of sudden deaths which Have 0 2 2 occurred within 24 h of the initial Control Not have 9 77 86 3.27 0.0654 attack was 78.2% of all cases 4). Total 9 79 88 The results of the present study support the findings of Uehata’s study that show most of the causes Case Latest change in work content4) p-value of unexpected natural deaths were Have Not have Total stroke, and most unexpected Have 0 1 1 natural deaths occurred within 24 Control Not have 6 82 88 4.17 0.0313 h of the initial attack. Some of the Total 6 83 89 causes in the abovementioned results can probably be presumed. 1) sudden heavy physical activity related to work and preceding the attack within 24 To be work-related, the accident h. 2) sudden severe emotional stress related to work and preceding the attack within must: (1) arise out of the 24 h. 3) change in work load preceding the attack within a week. 4) change in work employment, and (2) happen in the content preceding the attack within a month. course of the employment. The arising-out-of-the-employment requirement usually requires a with the development of a coronary heart disease, and sufficiently close relationship between the injury and the these work characteristics might be related to the nature of the employment. The in-the-course-of-the- incidence of myocardial infarction as a single risk factor6). employment requirement inquiry as to whether the Moreover, Jenkins suggested that people with a type A accident occurred within the time, place, and behavioral pattern known as a risk factor for ischemic circumstances of the employment. Employees injured heart disease, characterized by extremes of off the employer’s premises are generally outside the competitiveness, striving for achievement and course of the employment. In Korea the tendency has aggressiveness, could often be deeply involved and been for work-related attacks to be easily approved if the committed to their work, and other aspects of their lives attack occurred during work at the workplace, because relatively neglected7). The WHO committee report on ‘the in-the-course-of-the-employment requirement’ has work-related diseases, showing kinds of concerns, been emphasized in Korean criteria for recognizing emphasizes that short-term periods of stress bring on occupational cerebrovascular or cardiovascular diseases. temporary bouts of high blood pressure, and when such Families of the deceased tend not to claim cases which stressful conditions become chronic, they may lead to are decided to have occurred outside the workplace or continuous hypertension8). not during work time, shown in the present report. In In the present study, the incidence rate of unexpected addition, autopsies have rarely been performed in Korea, natural death was highest for the electricity/gas water and it is not easy to determine the cause of unexpected supply industries, in which workers tend to do a lot of natural death due to an acute heart attack without an shift work or night work. The suggestion that shift-work autopsy. Jungsun PARK, et al.: Unexpected Natural Death among Korean Workers 243 In this study, we matched the workplace of the case 3) WHO Exp. Committee. Sudden cardiac death. Geneva: and the control because ordinary working conditions are World Health Organization, 1985. (WHO Tech Rep Ser regarded as a confounding factor in the occurrence of 726: 5–25). unexpected natural death, and matching with a co-worker 4) Uehata T. Case study of “Karoshi” due to work-related made it possible to adjust for the differences in work cardiovascular attacks in Japan. In: Finnish Institute of Occupational Health ed. Proceedings of the style and the work environment. We tried to find International Symposium on New Epidemics in differences between cases and controls in working Occupational Health, Helsinki: Finnish Institute of conditions after matching for sex, age, and ordinary Occupational Health, 1994: 94–100. working conditions, and to get information on the factors 5) Cooper CL, Marshal J. Occupational sources of stress, causing the attack. The matched comparison of cases a review of the literature relating to coronary heart and controls showed that unexpected natural death among disease and mental ill health. J Occup Psychol 1976; Korean workers was associated with work-related stress 49; 11–28. such as heavy physical activity related to work within 24 6) Karasek R, Baker D, Marxer F, et al. Job decision h of the attack or a change in work content within a month latitude, job demands and cardiovascular disease. Am before the attack, so that unexpected natural death might J Public Health 1981; 71 (7): 694–705. be influenced by work-related stress4, 5, 11). In general, 7) Jenkins CD. Psychologic and social precursors of coronary disease (II). New Eng J Med 1971; 284 (6): high blood pressure (especially systolic pressure), 307–317. diabetes mellitus, and EKG abnormality (left ventricular 8) WHO Exp. Committee. Identification and control of hypertrophy or ST-T change), smoking history and serum work-related disease. Geneva: World Health cholesterol have been accepted as risk factors for sudden Organization, 1985. (WHO Tech Rep Ser 714: 22). death in many reports12–18), but such information was not 9) Akerstedt T, Knutsson A, Alfredsson L, et al. Shift work collected in the present study. and cardiovascular disease. Scand J Work Environ There are some limitations to this study. One is the Health 1984; 10: 409–414. selection bias. Our study subject was compensated 10) Kristensen TS. Cardiovascular disease and the work claimed cases. Claimed cases might be self-screened environment—A critical review of the epidemiologic before the family claimed. The other is the information literature on nonchemical factors. Scand J Work bias. The authors gathered the information on the Environ Health 1989; 15: 165–179. 11) Uehata T. Long working hours and occupational stress- deceased from documents submitted for a claim only, related cardiovascular attacks among middle-aged though living controls were interviewed directly. So we workers in Japan. J Hum Ergol 1991; 20: 147–153. lacked information on laboratory data after the attack, 12) Hoshuyama T, Saeki S, Takahashi K, et al. A the personal medical history, especially on hypertension Descriptive Epidemiology on Sudden Death among or diabetes mellitus, and risk factors for cardiovascular Workers. J UOEH 1992; 14 (3): 219–225 (in Japanese). diseases such as smoking, EKG abnormality, serum 13) Hoshuyama T, Saeki S, Takahashi K, et al. A Matched cholesterol, and alcohol consumption for unexpected Case-Control Study on Sudden Unexpected Death natural death cases. There may also be overestimation among Japanese Workers. J Epidemiol 1993; 3: 29– of work-related stress as a cause of death, because the 34. cause is investigated after death, and work-related stress 14) Kiryu Y, Suzuki S, Hosogai H, et al. A case-control might be carefully looked for. study on the risk factors of sudden death. Jpn J Ind Health 1994; 36: 16–23. In conclusion, unexpected natural death might be 15) Kannel WB, Gagnon DR, Cupples LA. Epidemiology influenced by work-related stress. More experimental of sudden coronary death: population at risk. Can J and epidemiological research must be carried out to Cardiol 1990; 6: 439–444. identify the exact risk factors or causes of cerebrovascular 16) Kannel WB, Plehn JF, Cupples LA. Cardiac failure or cardiovascular attack for prevention of unexpected and sudden death in the Framingham study. Am Heart natural death among middle-aged workers. J 1988; 115: 869–875. 17) K r e g e r B E , C u p p l e s L A , K a n n e l W B . T h e References electrocardiogram in prediction of sudden death: 1) Kwon I. Analysis of Sudden Unexpected Natural Death Framingham study experience. Am Heart J 1987; 113: in Legal Autopsy during 1990–1994. Annual Report 377–382. of National Institute of Scientific Investigation. 1995; 18) Kagan A, Yano K, Reed DM, et al. Predictors of sudden 27: 127–135 (in Korean). cardiac death among Hawaiian-Japanese men. Am J 2) Ministry of Labor. Labour Laws of Korea, Ministry of Epidemiol 1989; 130: 268–277. Labor Publication no. 1989.