Advance Publication INDUSTRIAL HEALTH Received: March 7, 2018 Accepted: July 25, 2018 J-STAGE Advance Published Date: August 8, 2018 1 Original article 2 Effects of Occupation on Intracerebral Hemorrhage-related Deaths in Inner Mongolia 3 4 Liqun Gao 1+，Maolin Du1+, Jiayi Li2+, Neng jun Zhao3, Ying Yang1, Chao Dong 1, Xiao 5 ling Sun4, Baofeng Chi1, Qingxia Wang1,Wenting Chen1, Chunfang Tian5,Nan Zhang1, Lehui 6 Li1, Li wei Niu1, Huiqiu Zheng1,Han Bao1,Yan Liu1,Juan Sun# 1 7 1Inner Mongolia Medical University, Hohhot, China 8 2Beijing Health Vocational College, Beijing, China 9 3 People's Hospital of Inner Mongolia Medical University, Hohhot, China 10 4 Inner Mongolia Normal University, Hohhot010022, Hohhot, China 11 5Inner Mongolia Autonomous Region Hospital of Traditional Chinese Medicine, Hohhot, 12 China 13 † Liqun Gao，Maolin Du, Jiayi Li contributed equally to this paper 14 Corresponding author 15 # Juan Sun 16 Address: Inner Mongolia Medical University, No. 5, Xinhua Street, Hohhot, Inner Mongolia 17 Autonomous Region, China 18 Tel: +086-1564-7170-443 19 Fax: +086-0471-6653-197 20 E-mail: [email protected] 21 Running title: Occupation on Intracerebral Hemorrhage-related Deaths 22 Received: March 7, 2018 23 Accepted: July 25, 2018 24 Advance publication: August 8, 2018 25 26 Abstract: 27 This study assessed the relationship between occupation and Intracerebral 28 Hemorrhage-related deaths and compared the differences in ICH-related deaths rates between 29 the eastern and midwestern regions of Inner Mongolia. We used the case-control method. 1 30 Cases included Intracerebral Hemorrhage-related deaths that occurred from 2009 to 2012 in 31 Inner Mongolia while controls included non-circulatory system disease deaths that occurred 32 during the same period. Odds ratios (ORs) for Intracerebral Hemorrhage-related deaths were 33 calculated using logistic regression analysis, estimated according to occupation, and adjusted 34 for marital status and age. The Intracerebral Hemorrhage mortality rate in the eastern regions 35 (125.19/100000) was nearly 3 times higher than that in the midwestern regions 36 (45.31/100000). ORs for agriculture-livestock workers, service professionals and general 37 workers, professional workers and senior officials were in descending order. The age-adjusted 38 OR for Intracerebral Hemorrhage-related deaths was lowest in unmarried men senior officials 39 (OR 0.37, 95% CI 0.14-0.99). The Intracerebral Hemorrhage mortality rate in the eastern 40 regions was much higher than that of the midwestern regions, since about 90% of 41 Intracerebral Hemorrhage-related deaths in the eastern regions were those of 42 agriculture-livestock workers who has the largest labor intensity of any other occupation 43 assessed. 44 45 Key words: Intracerebral hemorrhage, Mortality, Occupational health, Risk, Inner Mongolia 46 47 48 49 Introduction 50 Stroke is estimated to result in 134,000 deaths annually and is the third leading cause of 51 death (after heart disease and cancer) in the nation1). Stroke is classified primarily into 2 types, 52 ischemic (80%-85% of cases) and hemorrhage (15%-20% of cases) in Brazil and in Latin 53 America2). Intracerebral hemorrhage (ICH) accounts for 10–20% of strokes in Western 54 countries, however, can reach twice this proportion in Asia3, 4). In China, ICH accounts for up 55 to a third of all strokes5). ICH is the most serious and least treatable form of stroke; 56 additionally, it is associated with a mortality rate of up to 50%, and half of those who survive 57 are left with significant disabilities3). 58 Differences in the prevalence of major risk factors among the stroke subtypes, 59 demonstrating that knowledge of pathophysiology is essential for the proper management of 2 60 these patients. Given this, learning more about the epidemiologic data of the region is vital2). 61 In China, significant geographic variations in ICH mortality rates were observed, with higher 62 rates being found in the north and lower rates in the south6). Some studies have shown that 63 age, ethnicity, educational status, and marital status are associated with ICH 7-10). Compared 64 to other age groups, the older adult population is at a higher risk of ICH, as the mortality rate 65 in the ≥70 group has recently shown an alarming increase10). Although there are many studies 66 examining the relationship between cerebrovascular or stroke deaths and occupation, these 67 studies have not been conducted uniformly11-13). Some epidemiological studies investigating 68 the association between ICH-related deaths and occupation classified occupation in terms of 69 working hours14), socioeconomic status15), and work intensity16). Despite the potential for 70 certain occupations to increase the risk of stroke, the Guidelines for the Primary Prevention 71 of Stroke in America currently do not consider working conditions and labor intensity as 72 documented risk factors for cardiovascular diseases or stroke17). To our knowledge, so far, 73 there are no empirical studies examining the relationship between ICH-related deaths and 74 occupation in China. 75 Our previous study showed that circulatory system diseases are considered as the main 76 cause of death in Inner Mongolia18), however, we did not know about how ICH severity 77 relates to the circulatory system. Our objective was to evaluate the relationship between 78 occupation and ICH. The distance difference between the eastern and midwestern regions is 79 2400 km, which leads to a different geographical environment between eastern and 80 midwestern regions in Inner Mongolia. The latitude difference between the eastern and 81 midwestern regions is 29°, which leads to a different climate19). The above two reasons lead 82 to great differences in industrial characteristics. Since the differ greatly in terms of lifestyle, 83 temperature, and historical and geographical environments, we discuss the above-mentioned 84 relationship with regard to these regions. This study provides data for future research on ICH, 85 and the results may help guide future interventions. 86 Subjects and Methods 87 Data Source 88 The data were obtained from the Death Registry System (DRS), which is maintained by 89 the Ministry of Health of the People’s Republic of China and executed by the Inner Mongolia 3 90 Autonomous Region Centers for Disease Control and Prevention. The DRS uses a multistage 91 cluster probability sampling strategy stratified by region, local gross domestic product, 92 proportion of rural dwellers, and the total population of local areas20). The monitoring points 93 of the DRS in Inner Mongolia included Kailu County and Bairin Youqi (eastern); and Sonid 94 Youqi, the Muslim District, and the Linhe District (midwestern). All hospitals with adequate 95 diagnostic qualifications are responsible for recording all ICH-related deaths in the DRS. 96 These hospitals were divided into four levels: provincial, municipal, county, and township. 97 Clinical diagnosis can be provided in all four level hospitals. These diagnostic methods 98 include pathological, clinical, and surgical diagnoses, as well as postmortem evaluations. 99 Clinical diagnosis includes imaging diagnosis, pathological-anatomical diagnosis, the 100 diagnosis related to the need for surgery, and pathophysiological diagnosis20). In all cases, 101 ICH was diagnosed using cranial computed tomography, magnetic resonance imaging scans, 102 and complementary examinations. 103 We used data on the total population, total number of deaths, and number of ICH-related 104 deaths from 2009 to 2012. Cases included ICH-related deaths that occurred from 2009 to 105 2012. The original data on the number of deaths were coded (ICH codes I61.0–I61.9) 106 according to the Tenth Revision of the International Classification of Diseases. The controls 107 included deaths that were randomly selected from all non-circulatory system disease deaths 108 and were matched with the ICH-related death cases according to the time of death, area of 109 death, gender, and age (±2 years) in a 1:1 ratio. 110 All data were checked for eligibility and validity prior to analysis. The data collected in the 111 DRS included information on gender, age (<50 and ≥50), regions (rural and urban), ethnicity 112 (Mongolian, Han, and other), marital status (married and unmarried—unmarried included 113 those who were widowed or divorced), educational status (low [literature, and primary and 114 middle school] and high [college and university]), and occupational status (occupations were 115 categorized into the following 6 groups according to the PRC Occupational Classification: 116 senior officials, professional workers, general workers, service professionals, 117 agricultural-livestock workers, and others)21) . The classification of work intensity is based on 118 the recommendations of the Chinese Nutrition Society: it is divided into light work-intensity 119 (75% of the time to sit or stand, 25% of the time is a standing activity), including: senior 4 120 officials, moderate work-intensity(25% of the time to sit or stand, 75% time to engage in 121 special professional activities of medium intensity), including: service professionals, 122 professional workers, severe work-intensity(40% of the time to sit or stand, 60% of the time 123 to engage in special professional activities of heavy intensity), including: 124 agriculture-livestock workers, general workers22). “Others” refers to individuals who do not 125 fit into the other five occupations, such as those with an unclear occupation record or who 126 lack such a record, those without fixed work, and those who have never worked. 127 ICH is defined as (adapted from the Classification of Cerebrovascular Disease III-1989) a 128 spontaneous, nontraumatic, abrupt onset of severe headache, altered level of consciousness, 129 or focal neurological deficit that is associated with a focal collection of blood within the brain 130 parenchyma seen on neuroimaging or at autopsy and is not attributable to hemorrhagic 131 conversion of a cerebral infarction23). The procedure to identify the cause of death especially 132 when a person died at home was based on "the place of death" in registration records in DRS.