By Andrew M. Seaman
The number of smokers lighting up on hospital grounds has fallen about seven percentage points since 1995, according to a new study.
"It is encouraging that there has been improvement, but it's discouraging that the nicotine replacement therapy has not been able to put more of a dent into this," said the study's lead author Susan Regan, an instructor of medicine at Harvard Medical School in Boston.
The findings reflect the experience of Boston's Massachusetts General Hospital, where past research found that 25 percent of hospitalized smokers reported smoking on the grounds in 1995.
In the new study, which surveyed patients who smoked and were referred to the hospital's tobacco treatment program between 2007 to 2010, the researchers found that the number of smokers lighting up on hospital grounds during their entire stay fell to 18.4 percent.
One explanation for the decline, according to the researchers, is the increased use of nicotine replacement therapy patches, lozenges, gum and inhalers.
They write in the Archives of Internal Medicine that the use of nicotine replacement therapy at the hospital increased more than twelve-fold from 1995 to 2010.
However, they cannot say for certain that the therapy is the reason for the decline.
For example, the new study only included patients in the hospital's tobacco treatment program while the previous study included all patients who smoked. The researchers write that those who refused to take part in the program may have been more likely to sneak a smoke.
Regan told Reuters Health that an overall decline of smoking shouldn't directly influence their findings, because they only looked at the percentage of smokers who lit up.
As for smokers who still smoke while hospitalized, Regan told Reuters Health that some may just not be ready to quit.
"Many smokers are interested in quitting. Some are interested but not ready, and some are just not interested," she said.
In the new study, which followed about 5,400 smokers, the researchers found that certain characteristics were linked to a person being more likely to abstain from smoking, including being over 50 and having heart problems.
The Joint Commission, a nonprofit group that accredits more than 19,000 hospitals and other healthcare facilities, already prohibits U.S. hospitals from allowing smoking in their buildings.
Patients and staff, however, may smoke outside the building, unless the hospital bans that too.
In Massachusetts General's case, the hospital allows people to smoke at two smoking shelters on its property, which is where Regan said smokers most likely lit up.
"I think that if you really want to completely eliminate smoking, you have to make the (hospital) campus smoke free, but you're also going to have to prevent patients from leaving the floor to smoke," said Regan.
But, she added that brings up other questions, including how to not burden already busy nurses.
"There is no easy solution to this, but clearly making the campus smoke free is a step in the right direction," she said.
Dr. Steven Schroeder, who wrote an editorial accompanying the new study, agreed that smoke-free campuses are a good idea.
"There are many hospitals now that are making themselves totally smoke free. You may say that's not fair to the patient, but we can offer them nicotine replacement therapy," said Schroeder, of the University of California, San Francisco.
Regan warns, however, that these results are only based on one hospital, and the conditions it faces may not be the same as others.
"If you did it in a warm weather state, you might find more patients who are more likely to go out and smoke. But we don't know," said Regan.
More from NBCNews.com health: