|Alessandra Pia Porretta: a 21% reduction in STEMI admissions after smoking ban introduced. |
|Jonathan Emberson: ‘Older smokers still do considerably worse than older non-smokers.’ |
Further proof that a policy to ban smoking in public places works effectively in the battle against heart disease has emerged emphatically from a study of hospital admissions for ST elevated MIs in Switzerland’s first region to apply the ban. ‘Our study demonstrated a significant and long-lasting reduction in the incidence of STEMI admissions among the general population of Canton Ticino after the enforcement of a smoking ban,’ said investigator Alessandra Pia Porretta from San Giovanni Hospital, Bellinzona, speaking at a press conference yesterday.
Ticino is one of 26 Swiss cantons and introduced a smoking ban in April 2007. The study firstly compared data on STEMI hospitalisations (codified admissions and discharges) for the three years before the ban (2004-2007) with data for the three years after (2007-2010), and secondly compared the Ticino records with those from the canton of Basel City, where the smoking ban was then not yet introduced.
Results showed an overall statistically significant reduction in STEMI admissions of 21% following the smoking ban. This fall was most marked in the first year after introduction (-23.5% in 2007-2008), and thereafter STEMI incidence has remained roughly the same. The greatest reduction in STEMI admissions was observed in older people: a 27% post-ban decrease in both men and women over 65.
The results from this small canton Switzerland will come as no surprise. A meta-analysis published in Circulation in October last year suggested that the tougher statute, the greater the risk reduction. The investigators found that fully smoke-free laws were associated with a 15% reduction in hospitalisations for acute MI, reflecting similar decreases found in earlier studies.
However, the benefits of quitting smoking, although substantial, may not be as great as found in never-smokers. First, a Japanese study reported at the same press conference showed that short-term cessation does not completely remove endothelial damage caused by smoking.
And the prospective CONFIRM (Coronary CT Evaluation for Clinical Outcomes: An International Multicenter Study) registry of 13,372 patients from nine countries in Europe, North America and East Asia, identified a higher prevalence of severely blocked coronary arteries in both active and past smokers when compared to their never-smoking counterparts. Active and past smokers had a 1.5-fold higher probability of severe stenoses in one and two major heart arteries, and a 2-fold increased probability in all three major heart arteries, when assessed by coronary computed tomographic angiography.
However, this greater prevalence of arterial disease among the quitters was not reflected in greater rates of AMI or death, which remained comparable to those of the never-smokers after two years of follow-up. ‘So it’s never too late to quit,’ said James K. Min of New York-Presbyterian Hospital presenting the results.
Similarly, the Whitehall study of London civil servants has been tracking the health of 7000 older men from 1997 to 2012 and found over the 15-year study period (during which time 5000 of the 7000 men died) deaths in current smokers were about 50% higher than among the never-smokers, mainly because of vascular disease, cancer and respiratory disease. Smokers who survive to 70 still lose on average about four years of life.
Average subsequent life expectancy from age 70 was about 18 years for the men who had never regularly smoked, 16 years for those who had given up smoking before age 70, but only about 14 years for men who were still smoking at age 70. Two-thirds of never smokers, but only half of current smokers, survived from 70 to 85.
Dr Jonathan Emberson, a statistician at the University of Oxford, presenting the data said: ‘This study shows that even if you were to ignore all the deaths caused by smoking before the age of 70, older smokers still do considerably worse than older non-smokers, losing a considerable amount of subsequent lifespan.’
Previous studies have already shown that prolonged cigarette smoking from early adult life is associated with about 10 years loss of life expectancy, with about one quarter of smokers killed by their habit before the age of 70. Stopping at ages 60, 50, 40 or 30 gains back about three, six, nine or even the full ten years.