The Association Between Public Smoking Policy, Weather and Myocardial Infarction Incidence in Hong Kong

Goggins, W.B.

Background: Several studies from Europe and the United States have reported sharp drops in the incidence of acute myocardial infarction (AMI) following the introduction of smoking bans for public places in various cities. In addition some studies have reported that daily AMI hospitalization rates are associated with meteorological conditions, particularly temperature. Hong Kong banned smoking in restaurants, workplaces and outdoor public areas in 2007 and in bars and karaokes in mid-2009. In this study we examine whether AMI hospitalization rates dropped following introduction of the public smoking bans in Hong Kong and also whether daily AMI hospitalizations are influenced by meteorological conditions.

Methods: Data on all public hospital AMI admissions from Hong Kong were collected from 2000-2009 were collected. Generalized additive Poisson regression models were used to model the association between time trend, seasonality and meteorological variables and daily AMI admissions.

Results: The mean number of daily AMI admissions was 13.6. Before the introduction of the first smoking ban there was no consistent long-term trend in AMI hospitalization which first rose from 2001-2003, then declined until 2006. Hospitalizations rose slightly in 2007 and then sharply beginning in late 2008. Neither phase of the smoking ban was accompanied by a notable drop in hospitalizations. In terms of seasonality hospitalizations peaked December-February and were lowest from May-October. Colder temperatures were associated with more AMI hospitalization with an approximate 4% increase in hospitalization being associated with a 1C lower mean temperature over the previous 21 days. Higher humidity was modestly associated with fewer hospitalizations.

Discussion: Unlike previous studies our study did not find a sharp drop in AMI hospitalizations following the introduction of a public smoking ban. Other factors may influence long-term trends in AMI. Further observation of the AMI hospitalization rates in the future is necessary.