Those who urinate frequently at night have an increased risk of premature death, studies say

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Men and women who wake up frequently at night to urinate have an increased risk of premature death independent of the risk from disorders, such as an enlarged prostate, that are known to cause increased nighttime urination, researchers said Sunday. The risk is highest for young men and women, then declines with advancing age but still remains elevated, two groups reported at a San Francisco meeting of the American Urological Assn. The findings suggest that there may be other as-yet-unknown disorders that cause such nighttime urination, formally known as nocturia.

In one study, epidemiologist Varant Kupelian of the New England Research Institutes in Watertown, Mass., and his colleagues studied data from the Third National Health and Nutrition Examination Survey, conducted from 1988 to 1994, and linked the information to death certificates in the National Death Index. Their analysis included a sample of 15,988 men and women over the age of 20.

They found that the overall incidence of nocturia, defined as two or more episodes per night, was 15.5% among men and 20.9% among women. For the whole group, taking into account such confounding factors as an enlarged prostate, they found that nocturia was associated with a 49% increased risk of premature death in men and a 32% increased risk in women. Men between the ages of 20 and 49 had 2.56 times the normal risk, while women in that age group had a 10% increase. The highest-risk group among women was for ages 50 to 64, a 56% increase.

There is no clear explanation for the finding, Kupelian said at a news conference. ‘Chronic sleep loss adversely affects metabolic and endocrine function. Nocturia may be a marker of impending morbidity, such as cardiovascular disease or diabetes. Nocturia may also be a marker of overall health.’

In the second study, researchers at the Tohoku University School of Medicine in Sendai, Japan, studied 788 men and women age 70 and older in an urban district of northern Japan. Controlling for other variables, they found that the risk of death increased with the number of times a person rose during the night, with those rising four or more times having 3.6 times the normal risk.

The data show that the relationship between nocturia and premature mortality does not only affect the elderly, said Dr. Tomas L. Griebling, a spokesman for the urology association. People who suffer from the disorder at any age should alert their physician to the problem, he said.

-- Thomas H. Maugh II