Measuring the Impact of Smoke-free Legislation on Population Health in Two Cities of China

Abstract

Exposure to secondhand smoke (SHS) increases the risk of morbidity and premature mortality. Smoke-free legislation is an effective way to protect the population from the harms of SHS and has been implemented nation wide in at least 62 countries. The central government of China has not passed a national smoke-free law, but an increasing number of local governments (direct-controlled municipalities and provincial capitals) have enacted city level smoke-free laws that prohibit smoking in public places over the last decade. The primary objective was to estimate the impact of the smoke-free legislation on cardiovascular and cerebrovascular diseases in two smoke-free cities (Tianjin and Qingdao) and explore underlying reasons for the disparity in the magnitude of the effect of city level smoke-free legislations. As reliable population-level incidence data is crucial for assessing the effectiveness of preventive measures and the evaluation of the burden of disease, the second objective was to assess the completeness of case ascertainment for the surveillance of acute myocardial infarction (AMI) and stroke incident cases and to estimate the incidence of AMI and stroke in Tianjin. The first paper, Impact of smoke-free legislation on acute myocardial infarction and stroke mortality in Tianjin, China (2007-2015), was developed to estimate the change of AMI and stroke mortality rate associated with the implementation of the smoke-free legislation in Tianjin. The study utilized incidence and mortality data routinely collected in the chronic incidence surveillance system and all-cause mortality surveillance system respectively. An interrupted time series design adjusting for underlying secular trends, seasonal patterns, population size changes, and meteorological factors, was conducted to analyze the immediate and gradual effect of implementing the law on AMI and stroke events. There was an incremental 16% (RR: 0.84; 95% CI: 0.83–0.85) decrease per year in AMI mortality trend and a 2% (RR: 0.98; 95% CI: 0.97–0.99) annual decrease in stroke mortality trend among the population aged ≥ 35 years in Tianjin following the implementation of the smoke-free law. Immediate post-legislation reductions in mortality were not statistically significant due to the progressive enforcement of the law. An estimated 10,000 (22%) AMI deaths were prevented within 3.5 years of the implementation of the law. The second paper, Implementation matters: Assessment of Qingdao’s smoke-free legislation on hospitalizations and mortality of cardiovascular diseases using interrupted time series design, quantified the impact of the smoke-free legislation on cardiovascular and cerebrovascular diseases in Qingdao and explored the factors associated with the disparity in the magnitude of the effect. The study utilized data from electronic medical records, all-cause mortality surveillance system, existing program file, annual reports, governments’ work report, published and unpublished literature. The theory of change was used to map backwards and identify preconditions and contextual factors of success. The smoke-free legislation in Qingdao was associated with gradual reductions in AMI and stroke incidence. Demonstrable but modest effects on stroke admissions and AMI/stroke mortality rate were observed among the older age group after the law had been implemented for about one year. The impact of the smoke-free law on population health in Qingdao is lower than that in Tianjin mainly because Qingdao was outperformed by Tianjin and some other smoke-free cities in China in the implementation and enforcement of the smoke-free law, and in achieving most of the expected interim outcomes. Understaffing, the initial lack of designated funding for law enforcement and the absence of effective monitoring and evaluation scheme lead to insufficient enforcement of the law and consequent limited compliance, awareness and health impact in Qingdao. Therefore, active steps including capacity building for enforcement agency staff, routine monitoring, rigorous implementation of penalties should be taken to enhance coordinated enforcement compliance and achieve expected health impact in the population. The third paper, Assessing the completeness of incident AMI and stroke reporting in Tianjin, China, dealt with the issue arising in the evaluation of Tianjin’s smoke-free law on AMI and stroke incidence wherein the changes in the extent of missing reports biased the results. The DisMod II program was applied to model the incidence of AMI and stroke from other epidemiological indicators. The completeness of AMI and stroke incidence reporting was assessed by comparing the sex and age-specific incidence rates derived from the incidence surveillance system in 2007, 2010 and 2015 with the modeled incidence rates. The overall completeness of incidence report was 36% (95% CI: 35%-38%) for AMI and 54% (95% CI: 53%-55%) for stroke. Completeness of AMI and stroke incidence surveillance was low in Tianjin but has improved in recent years primarily owing to the incorporation of automatic reporting component into the information systems of health facilities, the increase in the utilization of healthcare service and campaigns promoting access to prevention services and timely emergency treatment for AMI and stroke.