Free Legislation on Acute Myocardial Infarction and Stroke Mortality
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Original research Tob Control: first published as 10.1136/tobaccocontrol-2018-054477 on 28 January 2019. Downloaded from Impact of smoke- free legislation on acute myocardial infarction and stroke mortality: Tianjin, China, 2007– 2015 Hong Xiao,1 Hui Zhang,2 Dezheng Wang,2 Chengfeng Shen,2 Zhongliang Xu,2 Ying Zhang,2 Guohong Jiang,2 Gonghuan Yang,3 Xia Wan,3 Mohsen Naghavi4 For numbered affiliations see ABSTRact which is responsible for approximately 230 000 end of article. Background Smoke- free legislation is an effective way deaths annually.7–9 The results from nation- to protect the population from the harms of secondhand ally representative surveys showed that 54% Correspondence to smoke and has been implemented in many countries. Professor Guohong Jiang, Tianjin of indoor employees smoke or were exposed to Centers for Disease Control and On 31 May 2012, Tianjin became one of the few cities SHS at worksites, 57% of youth were exposed to Prevention, Tianjin, China; in China to implement smoke- free legislation. We SHS inside enclosed public spaces and 44% were jiangguohongtjcdc@ 126. investigated the impact of smoke- free legislation on exposed at home.10 11 com and Professor Gonghuan mortality due to acute myocardial infarction (AMI) and Yang and Professor Xia Wan, Despite the high prevalence of smoking and SHS Institute of Basic Medical stroke in Tianjin. exposure, China lags behind other countries in Sciences, Chinese Academy Methods An interrupted time series design adjusting revising tobacco control legislation at the national of Medical Sciences/School of for underlying secular trends, seasonal patterns, level as required by the WHO FCTC and is the Basic Medicine, Peking Union population size changes and meteorological factors was Medical College, Beijing, only country from the BRICS (Brazil, Russia, India, conducted to analyse the impact of the smoke- free law 100005, China; China, South Africa) group that has not passed a yangghuan@ vip. sina. com, on the weekly mortality due to AMI and stroke. The study national smoke- free law.12 13 However, one encour- xiawan@ ibms. pumc. edu. cn period was from 1 January 2007 to 31 December 2015, aging step undertaken by the Chinese govern- with a 3.5- year postlegislation follow- up. ment in the lead- up to the national prohibition The abstract was accepted and Results Following the implementation of the smoke- presented in the 17th World of smoking in public places is the enactment and Conference on Tobacco or free law, there was a decline in the annual trends of implementation of smoke- free legislation in major AMI and stroke mortality. An incremental 16% (rate copyright. Health. (Xiao H., Yang G., Wan cities. Since 2008, at least 18 cities in China have X., Liu Y., Naghavi M. Impact ratio (RR): 0.84; 95% CI: 0.83 to 0.85) decrease per year of the smoke- free legislation taken promising steps to enact laws or regulations in AMI mortality and a 2% (RR: 0.98; 95% CI: 0.97 to 13 14 on the incidence and mortality 0.99) annual decrease in stroke mortality among the promoting smoke- free public places. of AMI and stroke in Tianjin 2 population aged ≥35 years in Tianjin was observed. Tianjin, the third largest city (area 11 860 km , China: analysis of routinely population 15.6 million) of China, first imple- collected data. Tobacco Induced Immediate postlegislation reductions in mortality were Diseases. 2018;16(1):A160. not statistically significant. An estimated 10 000 (22%) mented the smoke- free law on 31 May 2012. The doi:10.18332/tid/83971). AMI deaths were prevented within 3.5 years of the law prohibits smoking in select places, including indoor government offices, schools, healthcare Received 3 May 2018 implementation of the law. http://tobaccocontrol.bmj.com/ Revised 26 September 2018 Conclusion The smoke- free law in Tianjin was facilities, supermarkets and all public transporta- Accepted 3 October 2018 associated with reductions in AMI mortality. This tion. The law also bans smoking in other indoor Published Online First study reinforces the need for large- scale, effective and workplaces and public places including bars, 28 January 2019 comprehensive smoke- free laws at the national level in restaurants, hotels and other entertainment venues China. unless they have designated smoking rooms with an effective separate ventilation system. The smoke- free law specifies strong penalties for violations and a clear set of responsibilities for enforcement INTRODUCTION agencies. Exposure to secondhand smoke (SHS) increases the Following the implementation of the smoke-free risk of morbidity and premature mortality due to law in Tianjin, studies demonstrated reductions in on October 2, 2021 by guest. Protected cardiovascular and cerebrovascular diseases.1 Given SHS exposure and indoor particulate concentra- the evidence of the adverse health effects of SHS, tions, increases in smoke- free signage in indoor the WHO Framework Convention on Tobacco public areas and public awareness of the health Control (WHO FCTC) requires each member state 13 15 16 to adopt effective legislative measures to protect hazards of smoking and passive smoking. people from exposure to tobacco smoke in work- However, the evidence generated in these studies places and public areas.2 As of 2017, 55 countries is insufficient for understanding the health effects © Author(s) (or their of implementing the smoking ban. The aim of this employer(s)) 2020. Re-use had implemented a comprehensive smoke- free law 3 4 permitted under CC BY-NC . No covering all public places and workplaces. study was to assess the impact of the municipal commercial re-use . See rights China is the largest consumer and producer smoke- free legislation on acute myocardial infarc- and permissions. Published of tobacco, with over 300 million smokers who tion (AMI) and stroke mortality in Tianjin. This by BMJ. smoke approximately one-third of the cigarettes study is intended to fill the impact evaluation gap in 5 6 To cite: Xiao H, Zhang H, in the world. Additionally, approximately Tianjin and pave the way for similar evaluations to Wang D, et al. Tob Control 740 million non- smokers, including 180 million be adopted in other areas that have enacted or are 2020;29:61–67. children, in China are routinely exposed to SHS in the process of enacting smoke- free laws. Xiao H, et al. Tob Control 2020;29:61–67. doi:10.1136/tobaccocontrol-2018-054477 61 Original research Tob Control: first published as 10.1136/tobaccocontrol-2018-054477 on 28 January 2019. Downloaded from METHODS years. All models were adjusted for temperature and relative Data humidity. Subjects of the mortality analysis include all cases of AMI and The Poisson model equation estimating weekly events was stroke deaths among Tianjin permanent residents (with Tianjin expressed as follows: Hukou). Mortality data from January 2007 to December 2015 log Y = offset log P + β + β T + β Ban + β Ban T 0 1 2 3 ∗ ′ for Tianjin were obtained from the all- cause mortality surveil- + β cos 2T π + β sin 2T π + βk TM, RH + ε (4 ) 52∗ ( 5) 52∗ ( ) lance system which monitors the entire residential population of ( ) ( ) the city. This system was established in 1984 and has been main- where Y denotes the response (weekly( events),) P is the age tained by the local Centers for Disease Control and Prevention group and sex- specific population, T is the time elapsed since (CDC). The records include the date of death, underlying causes the start of the study, T’ is the time elapsed since the implemen- of death, age, sex, residential address and whether the death tation of the smoke- free law, β0 represents the baseline level at 17 occurred in a hospital setting or elsewhere. The cause of death T=0, β1 is the model coefficient for the weekly secular trend (the classification for the study period was based on the International underlying prelegislation trend), β2 is the coefficient of the indi- Classification of Disease, 10th Revision. The underlying causes cator variable Ban (coded 0 for preban period and 1 for postban of death selected for analysis included AMI (I21) and stroke period) denoting the level/instantaneous change following the (I60- I64). law, β3 indicates the slope/gradual change following the smoke- The recording process and quality control of the data have free law and βκ denotes the coefficients for a set of covariates of been described elsewhere.18 19 Death certificates filled out interest (TM: temperature, RH: relative humidity). by practising clinicians from hospitals or community clinical The estimated immediate relative change (in percentage) centers are required by law to be reported. Non-hospital deaths in the mortality rate from the prelegislation to postlegislation are ascertained through records from the police department and periods was quantified as 100(exp(β2)-1). The annual relative the government mortuary, as well as community clinicians. The change was quantified as 100(exp(52*β3)-1). Each sex and age underlying causes of non- hospital deaths are investigated through group (≥35, 35–64, 65–84, ≥85) was analysed separately. For interviews with the deceased’s relatives by trained community further validation that the final models were detecting true ban clinicians on a door- to- door basis. The district and municipal impact, two additional models were fitted with false smoke- free CDCs oversee and check the quality of death certificates at the law implementation dates at 6 months and 1 year prelegislation. primary and secondary levels, respectively. The municipal CDC The number of averted deaths associated with the city- level also provides technical training and support to staff involved in smoke- free law was calculated as the regression- based prediction the surveillance process.19 of the number of deaths from 1 January 2007 to 31 December 2015, subtracted from the predicted number of deaths without Data related to meteorology were obtained from the local copyright.