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Second-hand smoke tied to asthma severity

Tue Oct 18, 2005

By David Douglas

NEW YORK (Reuters Health) - Exposure to second-hand tobacco smoke appears to increase asthma severity and might even influence the risk of hospital admission, according to a new report.

"Our study showed that second-hand tobacco smoke can be harmful for adults with asthma," lead investigator Dr. Mark D. Eisner told Reuters Health. "These results provide further justification for banning smoking in public places."

Eisner of the University of California, San Francisco and colleagues note that most previous studies of asthma and passive smoking have relied on self-reported exposure.

In the present study, published in the journal Thorax, the researchers used nicotine badges to measure exposure. The badges trap ambient nicotine in a filter, and gas chromatography is subsequently used to evaluate the content. Hair was sampled for nicotine and its major metabolite cotinine to determine the levels of longer-term exposure.

The badges were used for seven days in 189 subjects who had had a recent asthma hospitalization. A similar group of 138 asthmatics submitted hair samples to determine exposure in the previous three months.

Asthma severity over these time periods was established by telephone interviews.

Most of the subjects were exposed to second-hand smoke, with estimates ranging from 60 percent to 83 percent. The highest levels of recent exposure as determined by the badge were related to greater asthma severity.

Those with the highest levels of nicotine exposure in the previous month appeared to be at greater risk of hospital admission.

In an accompanying editorial, Dr. J. Britton of City Hospital, Nottingham, UK notes that the results are consistent with the "interpretation that individuals with higher levels of passive smoke exposure had more troublesome asthma."

However, "the findings on the risk of hospitalization were perhaps less convincing." This was due to the observational nature of the study and the low participation rate of eligible subjects.

Nevertheless, he concludes that "smoke exposure is likely to be bad for all people with asthma who would be well advised to avoid exposure, as indeed is the case for everyone else."

SOURCE: Thorax, October 2005.


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