WASHINGTON Glaucoma drugs appear to reduce the likelihood of death among patients using them compared with those patients receiving no treatment but it is not clear why, U.S. researchers said on Monday.
A four-year study involving more than 21,000 Americans found an association between all types of glaucoma medications and a lower death rate, the researchers wrote in the journal Archives of Ophthalmology.
"Our main finding were that people who filled at least one 30-day prescription for a medication had a 74 percent reduced hazard of death as compared to those who received no medications," Dr. Joshua Stein of the University of Michigan, who led the study, said in a telephone interview.
"Then we looked at different types of medications, different combinations of drugs and numbers of medications and we showed that for the various classes of medications this protective effect seemed to hold true," said Stein.
He said researchers do not know why patients using these drugs may live longer than those who do not, but one possibility may be the medications themselves.
"Certain classes of medications that can lower blood pressure, which is a risk factor for heart attacks and strokes, are helpful in people who have irregular heart rates. Other medications are useful in patients who have congestive heart failure," he said.
It could also be that people who go to their eye doctors regularly for glaucoma treatment may just be more health conscious and others may have limited access to health care, Stein said.
He said more research is needed to determine what is behind the association because the findings may have important clinical implications.
"If we know that certain classes of medication that we're prescribing may be increasing or decreasing one's risk of death then it may influence which types of medications we would want to describe to patients," he said.
Glaucoma, which damages the optic nerve, is the second leading cause of blindness and the No. 1 cause of blindness among African Americans, according to the World Health Organization.
A team at Johns Hopkins University in Baltimore projected in 2006 that there will be will be 60.5 million people with glaucoma by this year, increasing to 79.6 million by 2020.
Stein and colleagues studied billing records of 21,506 patients in a managed health care network in Michigan between 2003 and 2007, keeping track of all the medications prescribed.
Half were diagnosed with one or more types of glaucoma; the rest did not yet have nerve damage but were being monitored for glaucoma. The patients ranged in age from 40 to 60.
During the study, 6,049 people filled one or more prescriptions for a glaucoma medication and 2,021 had glaucoma surgery," the researchers wrote. They said 237 people died during the four-year study period.
(Editing by Maggie Fox and Cynthia Osterman)