Montana law shows public health impact
MIs [Heart Attacks] Plummet After Smoking Ban
Mitchel L. Zoler
CHICAGO — A ban on smoking in public places in Helena, Montana, led to an immediate 60% drop in the incidence of myocardial infarctions [heart attacks].
The surprising finding was observable because of a unique geographic and health care situation—all heart disease patients from Helena and two other surrounding communities are treated at a single hospital. The study involved an analysis by residence of all MI [heart attack] cases treated at that hospital over a 4-year period. The two communities surrounding Helena did not have a smoking ban and did not show evidence of any changes in the incidence of MI.
“As far as we can tell, this is the first study of its kind,” said Dr. Richard P. Sargent, a family physician in Helena, who presented the findings at the annual meeting of the American College of Cardiology. To be convincing, the findings need to be duplicated in another study in a different location with a smoking ban.
“This is a wonderful study with potentially great public health implications,” Dr. Guy S. Reeder, a cardiologist at the Mayo Clinic in Rochester, Minnesota, commented at the meeting.
Dr. Sargent urged publicizing the findings “so that people understand that second-hand smoke has an immediate effect on heart disease.” Tobacco smoke in the air can trigger immediate changes in platelet aggregation and vasoconstriction. A few hours of smoke exposure also can increase the risk of arrhythmias.
The study was possible because of a sweeping ordinance passed in Helena on June 4, 2002, that went into effect the following day. The law banned smoking in all workplaces, restaurants, bars, casinos, bowling alleys, and all other indoor public areas in the town, which has a population of about 28,000 people. Compliance was good, with 4 of 118 restaurants and bars having consistent violations during the following 6 months.
A traffic ticket-like citation was given to people who violated the ordinance. This enforcement system, suspended on Dec. 3, 2002, was challenged because the scheme did not allow for a jury trial. As of April 2003, enforcement remained suspended pending the outcome of this challenge.
But the 6 months of active enforcement, from June through December, allowed Dr. Sargent and his associates to assess the impact of a substantial cutback in second-hand smoke on public health. They reviewed the number of patients with myocardial infarctions admitted to Helena's only cardiology facility, at St. Peter's Community Hospital, during the 6 months of the smoking ban as well as during the 4 years before the ordinance went into effect. Because Helena and its surrounding three counties are geographically isolated, essentially all patients with myocardial infarctions that occurred in this region would have been treated at this hospital.
The researchers focused on patients with a primary diagnosis of myocardial infarction, as well as those with a secondary diagnosis that reflected an incident infarction, such as cardiac arrest. Patients with a true secondary myocardial infarction, such as those who had an infarction following surgery, were excluded.
Patients were counted as having their myocardial infarction in Helena if they were residents of the town, or if they had spent a night in a hotel or had eaten at least one meal in Helena immediately before their myocardial infarction. Patients who came from areas surrounding Helena, where the smoking ordinance was not in effect, served as a geographic control group.
The analysis showed that during the 4 years before the ordinance, an average of six to seven Helena residents or visitors had a myocardial infarction each month. Once the ordinance went into effect, this rate immediately dropped to an average of two or three myocardial infarctions a month. This decline of 60%, about four events per month, was statistically significant, Dr. Sargent reported. In addition, there was no detectable change in the incidence of myocardial infarctions among people who lived or ate outside of Helena.
Preliminary analysis of myocardial infarction rates after enforcement of the ordinance stopped last December suggests that the incidence of events has rebounded to the level seen before the ordinance passed.