Objective: To examine trends in Acute Myocardial Infarction (AMI) hospital admissions in Christchurch, New Zealand before and after the implementation of the New Zealand Smokefree Environments Act 2003 in December 2004.
Methods: Data on AMI hospital admissions to Christchurch Public Hospital were extracted for the period 2003 to 2006. Poisson regression was used to calculate rate ratios by comparing for AMI rates of hospital admissions before (2003/04) and after (2005/06) the introduction of the Smokefree legislation, and to assess whether there was a significant change over time.
Results: The introduction of the smokefree legislation was associated with a 5% reduction in AMI admissions. The 55-74 age group recorded the greatest decrease in admissions (9%) and this figure rose to 13% among never smokers in this group. Reductions were more marked for men. Adding the effects of area deprivation increased the reduction to 21% among 55-74 year olds living in more affluent (quintile 2) areas. Overall however, the statistical association of changing levels of AMI admissions with smoking status and with deprivation was not consistently significant.
Conclusion: At this early stage following the smokefree legislation, there are hints emerging of a positive impact on AMI admissions but these suggestions cannot yet be treated with certainty. Further research could usefully evaluate the longer-term effects of smoking legislation on the prevalence of smoking and exposure to second hand smoke, especially in more deprived urban communities.