Declines in Acute Myocardial Infarction After Smoke-Free Laws and Individual Risk Attributable to Secondhand Smoke

Q: What are the key findings of this study?

Strong smoke-free legislation reduced the community rate of acute myocardial infarction hospitalizations at 12 months with a pooled relative risk of 0.83 (95% CI 0.80-0.87).

Q: What is the clinical evidence from this study?

Study design: Meta-Analysis. Population: Acute myocardial infarction (AMI). Intervention: Strong public and workplace smoke-free legislation vs. Pre-legislation period (before implementation of a smoking restriction law). Primary outcome: Ratio of community rates of acute myocardial infarction hospitalization 12 months after versus before implementation of a smoking restriction law (RR 0.83, 95% CI 0.80 to 0.87).

Q: What does this research mean for the field?

Implementation of strong smoke-free legislation reduces community acute myocardial infarction hospitalization rates by 17% at 12 months, with reductions growing over time. Novelty: ClaimNovelty.SYNTHESIS. Consensus alignment: ConsensusAlignment.NEUTRAL.

James Lightwood; Stanton A. Glantz

doi:10.1161/circulationaha.109.870691

September 21, 2009CirculationOpen Access

Declines in Acute Myocardial Infarction After Smoke-Free Laws and Individual Risk Attributable to Secondhand Smoke

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Key result

Smoke-free legislation cuts community acute myocardial infarction hospitalizations ~17% at 12 months.

RR 0.83
95% CI 0.80 to 0.87

Why the study?

Does the implementation of strong public and workplace smoke-free laws reduce community hospital admission rates for acute myocardial infarction consistent with individual risks attributable to secondhand smoke?

Key Points

To determine whether community-level reductions in heart attack rates following smoke-free legislation are consistent with individual risk estimates from secondhand smoke exposure.
Conducted random-effects meta-analyses and meta-regression of community acute myocardial infarction admission rate ratios before and after smoke-free legislation across five countries.
Standardized relative risk estimates to 12 months of follow-up and compared observed community rate ratios against 48 mathematical simulation scenarios of individual risk and exposure.
The unadjusted pooled relative risk of acute myocardial infarction hospitalization was 0.81 (95% CI, 0.78 to 0.85), which standardized to 0.83 (95% CI, 0.80 to 0.87) at 12 months post-implementation.
Duration of follow-up accounted for 76% of between-study variance, with the natural log of relative risk declining by 0.0113 per month (SE 0.002, P<0.0005).
Community heart attack rates dropped by about 15% during the first year and reached a decline of about 36% at 3 years, matching point estimates from 8 of 48 individual risk simulation scenarios.

Study Design

Type

Meta-Analysis

Multicenter

Yes

Structured PICO

Does the implementation of strong public and workplace smoke-free laws reduce community hospital admission rates for acute myocardial infarction consistent with individual risks attributable to secondhand smoke?

P

Population

Community populations across 13 observational studies in North America and Europe evaluated for hospital admissions of acute myocardial infarction before and up to 36 months after implementation of strong smoke-free laws.

E

Exposure

Implementation of strong public and workplace smoke-free restriction laws (100% smoke-free public areas and workplaces)

C

Comparator

Community rates prior to the implementation of the smoking restriction law

O

Outcome

Ratio of community rates of acute myocardial infarction (AMI) hospital admissions after divided by before implementation of a smoking restriction law, standardized to 12 months post-implementationhard clinical

Main Result

Relative Risk: 0.83 (95% CI 0.8–0.87)

Passage of strong smoke-free legislation produces a rapid 17% reduction in community acute myocardial infarction hospitalizations at 1 year that grows with time and aligns mathematically with individual secondhand smoke risk estimates.

Limitations

Lack of biomarker-based (cotinine) levels of general population exposure to secondhand smoke before and after laws went into effect
Lack of reliable data on individual smoking status and cotinine measures at the time of hospital admission for subjects in the included studies
Model did not account for lower secondhand smoke exposure among people who quit smoking following the law or reduced consumption among continuing smokers
Model parameters were treated as independently distributed even though some may covary, and parameter distributions were taken from observational studies subject to bias
Lack of biomarker-based (serum cotinine) levels of general population exposure to secondhand smoke before and after laws went into effect
Lack of reliable data on smoking status or cotinine measures at the time of admission for patients in the included studies
Simulation model did not account for lower secondhand smoke exposure among people who quit smoking following the law or reduced cigarette consumption among continuing smokers
Model parameters were treated as independently distributed despite potential covariance, and were derived from observational studies subject to biases
Some overlap in baseline/case data among four included reports from Pueblo, Colorado and Piedmont, Italy treated as independent observations (though sensitivity analyses dropping overlapping studies showed no noticeable change)

Implication

Strong smoke-free legislation is associated with reduced AMI hospitalizations; extends evidence and confirms consistency with individual secondhand smoke risks.

Abstract

BACKGROUND: The estimated effects of recent pubic and workplace smoking restriction laws suggest that they produce significant declines in community rates of heart attack. The consistency of these declines with existing estimates of the relative risk of heart attack in individuals attributable to passive smoking exposure is poorly understood. The objective is to determine the consistency of estimates of reductions in community rates of heart attacks resulting from smoking restriction laws with estimates of the relative risk of heart disease in individuals exposed to passive smoking. METHODS AND RESULTS: Meta-analyses of existing estimates of declines in community rates were compared with a mathematical model of the relationship between individual risk and community rates. The outcome measure is the ratio of community rates of acute myocardial infarction (after divided by before implementation of a smoking restriction law). There is a significant drop in the rate of acute myocardial infarction hospital admissions associated with the implementation of strong smoke-free legislation. The primary reason for heterogeneity in results of different studies is the duration of follow-up after adoption of the law. The pooled random-effects estimate of the rate of acute myocardial infarction hospitalization 12 months after implementation of the law is 0.83 (95% confidence interval, 0.80 to 0.87), and this benefit grows with time. This drop in admissions is consistent with a range of plausible individual risk and exposure scenarios. CONCLUSIONS: Passage of strong smoke-free legislation produces rapid and substantial benefits in terms of reduced acute myocardial infarctions, and these benefits grow with time.

Discussion

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Cite This Study

Lightwood et al. (2009) conducted a meta-analysis in Acute myocardial infarction (AMI). Strong public and workplace smoke-free legislation vs. Pre-legislation period (before implementation of a smoking restriction law) was evaluated on Ratio of community rates of acute myocardial infarction hospitalization 12 months after versus before implementation of a smoking restriction law (RR 0.83, 95% CI 0.80 to 0.87). Strong smoke-free legislation reduced the community rate of acute myocardial infarction hospitalizations at 12 months with a pooled relative risk of 0.83 (95% CI 0.80-0.87).

synapsesocial.com/papers/6a706f7f78a11c550e0a56e2 https://doi.org/10.1161/circulationaha.109.870691

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Declines in Acute Myocardial Infarction After Smoke-Free Laws and Individual Risk Attributable to Secondhand Smoke

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

Declines in Acute Myocardial Infarction After Smoke-Free Laws and Individual Risk Attributable to Secondhand Smoke

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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