Impact of Smoke-Free Legislation on Acute Myocardial Infarction and Subtypes of Stroke Incidence in Shenzhen, China, 2012-2016: An Interrupted Time Series Analysis

Objective This study assesses the impact of smoke-free legislation on the incidence rate for acute myocardial infarction (AMI) and stroke in Shenzhen.Methods Data on ischemic (n = 72,945) and hemorrhagic (n = 18,659) stroke and AMI (n = 17,431) incidence covering about 12 million people in Shenzhen from 2012 to 2016 were used. Immediate and gradual changes in incidence rates were analyzed using segmented Poisson regression.Results Following the smoke-free legislation, a 9% (95% CI: 3%-15%) immediate reduction was observed in AMI incidence, especially in men (8%, 95% CI: 1%-14%) and in those aged 65 years and older (17%, 95% CI: 9%-25%). The gradual annual benefits were observed only in hemorrhagic and ischemic stroke incidence, with a 7% (95% CI: 2%-11%) and 6% (95% CI: 4%-8%) decrease per year, respectively. This health effect extended gradually to the 50-64 age group. In addition, neither the immediate nor gradual decrease in stroke and AMI incidence rates did not show statistical significance among the 35-49 age group (P > 0.05).Conclusion Smoke-free legislation was enforced well in Shenzhen, which would generate good experiences for other cities to enact and enforce smoke-free laws. This study also provided more evidence of the health benefits of smoke-free laws on stroke and AMI.