The impact of Shanghai's comprehensive smoke-free legislation on hospital admission and mortality rates for chronic obstructive pulmonary disease: an interrupted time series analysis.

introductionSmoking and secondhand smoke pose major global health risks, contributing to chronic obstructive pulmonary disease (COPD). Evidence on the health impact of Shanghai's smoke-free legislation is limited. This study assesses the effects of Shanghai's smoke-free legislation on COPD hospital admission and mortality rates.

methodsChronic obstructive pulmonary disease hospital admissions and deaths from July 2013 to December 2019 were analyzed using interrupted time series. Adjustments were made for demographics, weather, PM2.5, and seasonality.

resultsA total of 358 941 COPD hospital admissions and 56 824 deaths were recorded. After implementation of the legislation, there was no evidence of a short-term reduction in either COPD hospital admissions or mortality among adults aged ≥35 years. Both COPD hospital admissions and mortality showed downward trends over the longer term, although these overall changes were not statistically significant. Subgroup analysis revealed a modest but statistically significant long-term decline in admissions among adults aged 35-64 years (β = -0.06, P<.05), while no statistically significant short-term mortality change was observed among adults aged ≥65 years. Age-standardized analyses and Poisson and negative binomial sensitivity models yielded similar admission trends and broadly consistent long-term mortality patterns.

conclusionsThe implementation of the legislation was associated with a long-term downward trend in COPD-related hospital admissions and mortality, but the overall impact to date appears to be limited. Sustained implementation of stringent tobacco control policies is therefore recommended, alongside further improvement and expansion of existing measures to strengthen enforcement and broaden interventions, especially for outdoor smoking, to achieve greater health benefits. IMPLICATIONS: This study provides empirical evidence that Shanghai's comprehensive smoke-free legislation was not associated with a detectable short-term reduction in either COPD hospital admissions or mortality. However, both outcomes showed downward trends over the longer term, with reductions in hospital admissions appearing more pronounced among older adults, underscoring that the health benefits of smoke-free policies may accrue gradually through sustained implementation. Strengthening enforcement, expanding smoke-free areas, and integrating complementary public health interventions-such as smoking cessation support and stricter outdoor smoking regulations-could enhance the long-term effectiveness of tobacco control policies. These findings highlight the need for continuous evaluation and policy refinement to maximize public health benefits and reduce the overall burden of COPD in urban populations.