DG DISPATCH - EFNS
By Alice Goodman Special to DG News
LISBON, PORTUGAL -- Sept. 9, 1999 -- Cigarette smoking has been implicated in multiple sclerosis (MS), according to a large retrospective review presented at the Fourth Congress of the European Federation of Neurological Scientists.
"Cigarette smoking is not considered to be a risk factor for MS, but previous epidemiologic studies have been small and inconclusive," explained lead author Miguel Hernan, MD, department of epidemiology, Harvard School of Public Health, Boston.
The study analysed the association between the incidence of MS and cigarette smoking in two cohorts of large U.S. studies of women -- The Nurses Health Study (NHS), which included 121,700 women between the ages of 30 and 55 at baseline when enrolled in 1976; and HS-Part II, which included 116,671 women aged 25 to 42 years at baseline in 1989.
The study identified 312 definite or probable cases of MS that developed between 1976 and 1994 in NHS-Part I and between 1989 and 1995 in NHS-Part II. Compared to women who never smoked, the relative risk (RR) of MS was 1.6 among current smokers and 1.2 among past smokers (95 percent confidence intervals), after adjusting for age, geographical latitude and ancestry (all putative risk factors).
Moreover, the RR increased significantly with cumulative exposure to cigarettes -- a relative risk of 1.1 for women who smoked one to nine pack years, 1.5 for those who smoked 10-24 pack years, and 1.7 for those who smoked more than 25 pack years.
"If confirmed, these findings could provide new insights into the etiology
and prevention of MS," Dr. Hernan said.