Public smoking ban slashes heart attacks

15:30 01 April 03 NewScientist.com news service

A six-month ban on smoking in all public places slashed the number of heart attacks in a US town by almost a half, a new study has revealed.

The researchers attribute the dramatic drop to the "near elimination" of harmful effects of "second-hand" smoke - passive smoking. A smoke-free environment also encourages smokers to reduce smoking or quit altogether, the team adds.

Statistician Stanton Glantz, at the University of California, San Francisco, and colleagues studied diagnoses of heart attacks in the town of Helena, Montana, where the ban was imposed.

"This striking finding suggests that protecting people from toxins in second-hand smoke not only makes life more pleasant, it immediately starts saving lives," Glantz says. The researchers claim the study is the first to show that smoke-free policies rapidly reduce heart attacks, as well as having long-term benefits.

"This clearly shows the great need for controls on smoking in public places," says Amanda Sandford of UK pressure group Action on Smoking and Health. "Passive smoking is a killer. The public certainly underestimates the impact of passive smoking on the heart."

Small dose, large impact

The smoking ban in Helena was introduced in June 2002 but was suspended after six months because of a legal challenge. Glantz and researchers at St Peter's Community Hospital in Helena compared the hospital charts of heart attack patients admitted from the smoke-free town with those from neighbouring areas, as well as with records from Helena in the four years before the ban.

During an average six-month period, heart attack admissions to the hospital had averaged just under seven per month. But this fell to less than four a month during the smoking ban.

The study suggests that although second-hand smoke delivers only a small dose of harmful chemicals, it appears to have a very heavy impact on health. This paradox has puzzled scientists before, says Robert West, an expert on smoking cessation at St George's Medical School, London, "but there are now plausible mechanisms for this".

Immediate and acute

The risk of lung cancer rises steadily with the amount of tobacco a person smokes, he notes, but the risk of heart attack shows a non-linear relationship. Recent studies have shown "there is an immediate and acute effect of passive smoke exposure as a particulate pollutant," West told New Scientist.

The mechanism for this effect is likely to be that the inhaled smoke stimulates the immediate production of macrophages - white blood cells that "clean up the system".

But these break down and lead to the production of blood clotting agents. "So if someone is teetering on the brink of a heart attack, this clotting is likely to tip them over," says West.

Sandford notes that many public smoking bans are becoming more common. New York banned smoking from 30 March, and the Republic of Ireland will introduce a ban on smoking in the workplace - including pubs and restaurants - from January 2004.

The study was presented on Tuesday at the American College of Cardiology's annual meeting in Chicago


Shaoni Bhattacharya

Low Testosterone Affects Many Men With Coronary Disease


By Stephen Pincock

GLASGOW (Reuters Health) Mar 25 - Around 50% of men with coronary heart disease have low levels of testosterone that could have contributed to the development of the disease, British researchers reported on Tuesday.

At the British Endocrine Societies' 22nd joint meeting, Professor T. Hugh Jones from the University of Sheffield Medical School reported data from a study of 831 men with significant coronary disease, defined as either 70% coronary artery stenosis or 50% stenosis of the main stem artery. Men with active inflammation were excluded because this is known to lower testosterone levels.

Total testosterone and bioavailable testosterone levels were measured prior to elective coronary angiograms, Professor Jones told Reuters Health.

Previous research has linked low testosterone levels to dyslipidemia, hypertension, insulin resistance, obesity and a prothrombotic state, but the scale of the problem has not been established.

"We took this on because nobody had done anything about it for years. And what we've shown is that men with coronary heart disease have got lower testosterone levels than men with clean coronary arteries," Professor Jones said.

The study showed that 23.4% of these men had either total testosterone or bioactive testosterone levels in the hypogonadal range--less than 7.5 nmol/L. There was also a group whose total levels were in the bottom of the normal range, between 7.5 and 12 nmol/L, suggesting the amount of the hormone circulating in their blood had dropped from higher levels.

"If you include those in the analysis, 52.9% are testosterone deficient," Professor Jones said. "This is really quite a large number of potential people who may need testosterone replacement."

About 17% or 18% of the general population of men would be expected to have low testosterone levels, the researcher said.

Obese men and men with hypertension were more likely to have low testosterone levels, and as expected the prevalence of the condition was higher in older men.

"A lot of these men should be on testosterone replacement if they want it," Professor Jones said, adding that his group and others have shown that this treatment can improve heart disease symptoms. "Obviously they would need to be evaluated individually."

He noted that hormone replacement therapy for men is "isn't very widespread at the moment," although that seems to be changing. Testosterone can be delivered via weekly muscle injections, pellets injected into the abdomen or patches.

A testosterone gel that is available in the US is soon to be launched in the UK.

Epstein-Barr Virus Linked to Multiple Sclerosis

Laurie Barclay, MD

March 25, 2003 — Epstein-Barr virus (EBV) is associated with increased risk of multiple sclerosis (MS), according to the results of a large, nested, case-control study published in the March 26 issue of The Journal of the American Medical Association.

"The baseline geometric mean serum antibody titers to EBV were consistently higher among individuals who later developed MS than among their matched controls," write Lynn I. Levin, PhD, MPH, from the U.S. Army Physical Disability Agency in Washington, D.C., and colleagues. "Similarly strong positive associations between EBV antibodies and risk of MS were already present in samples collected five or more years before MS onset."

Using the Department of Defense Serum Repository of blood samples collected between 1988 and 2000 from more than 3 million U.S. military personnel, the investigators identified 83 individuals granted temporary or permanent disability because of MS. Two controls for each of these cases were matched by age, sex, race, ethnicity, and dates of blood sample collection. The mean length of time between blood collection and onset of MS was four years.

The strongest predictors of MS were serum levels of IgG antibodies to EBV viral capsid antigen (VCA) or nuclear antigen (EBNA) complex. Rising levels of these antibodies correlated linearly with increasing risk of MS. Compared with those in the group of lowest VCA titers (/= 2,560) was 19.7 (95% confidence interval [CI], 2.2 - 174; P for trend = .004). Compared with those who had EBNA complex titers /= 1,280 was 33.9 (95% CI, 4.1 - 283; P for trend <.001.

Samples collected five years or more before MS onset also showed strong positive associations between EBV antibodies and risk of MS. No relationship was detected between cytomegalovirus antibodies and risk of MS.

According to the authors, these findings suggest that "the increased antibody response to EBV occurs early in relation to the pathological process that leads to demyelination and clinical disease," and that "there is a long lag time between infection with EBV and occurrence of MS.... These results support a role for EBV in the etiology of MS."

JAMA. 2003;289:1533-1536

Reviewed by Gary D. Vogin, MD