Nocturia and increased mortality risk

Nocturia significantly increased mortality risk in men and women, according to data from a government health survey.  Overall, awakening more than twice a night to urinate increased mortality risk by 50% in men and by more than 30% among women. Nocturia doubled the mortality risk of people younger than 65, and the effect was independent of comorbidities.

The finding has no clear explanation, but several possibilities exist, Varant Kupelian, PhD, said at the American Urological Association meeting.

“Chronic sleep loss adversely effects metabolic and endocrine function,” said Kupelian, of the New England Research Institutes in Watertown, Mass. “Nocturia may be a marker of impending morbidity, such as cardiovascular disease or diabetes. Nocturia may also be a marker of overall health.”

Nocturia is the most commonly cited reason for awakening by men and women alike. Sleep-interrupting trips to the toilet increase the risk of falls and hip fractures and are associated with certain chronic diseases, including hypertension, diabetes, and cardiovascular disease (CVD), said Kupelian.

At least two studies have shown that nocturia increases mortality risk in older people (BJU Int 1999; 84: 297-301, Am J Cardiol 2006; 98: 1311-1315). Whether the association exists in younger people had not been examined.

To extend the investigation of nocturia and mortality into the general population, Kupelian and colleagues analyzed data from the Third National Health and Nutrition Examination Survey (NHANES III), covering the period 1988 to 1994. The survey included a question about nighttime awakenings to urinate, with responses ranging from 0 to 3 or more.

The analysis comprised an NHANES III sample of 16,000 men and women 20 and older. Median follow-up was 8.8 years, and deaths were ascertained by linking the NHANES III database to the National Death Index.

Overall, 15.5% of men and 20.9% of women reported two or more nightly awakenings to urinate.

Consistent with other studies, the prevalence of nocturia increased with age, ranging from fewer than 5% of men and women 39 and younger to 15% to 20% of people ages 50 to 79, and to more than 20% of men and women 80 or older.

The investigators compared mortality in men and women who had fewer than two episodes of nocturia nightly with those who had two or more episodes. Nocturia increased the mortality hazard by 49% in men (HR 1.49, 95% CI 1.25-1.78, P<0.001) and by 32% in women (HR 1.32, 95% CI 1.14-1.51, P<0.001).

Stratification by age resulted in the unexpected finding of a higher mortality risk in younger people.

Two or more episodes of nocturia more than doubled the hazard in men ages 20 to 49 (HR 2.56, 95% CI 1.32-4.94, P=0.006), whereas women in the same age group had a lower mortality risk (HR 1.10, 95% CI 0.66-1.86).

Among people ages 50 to 64, more frequent nocturia significantly increased the mortality risk in men (HR 1.60, 95% CI 1.06-2.41, P=0.026) and women (HR 1.94, 95% CI 1.27-2.96, P=0.003).

The risk then declined in older individuals but was still increased in men (HR 1.35, 95% CI 1.11-1.63, P=0.003) and women (HR 1.19, 95% CI 1.04-1.37, P=0.012).

Nocturia remained a significant marker of increased mortality risk in an analysis of comorbid conditions. In men and women, more frequent episodes of nocturia had a greater effect on mortality risk in people who did not have cardiovascular disease or diabetes than among people who had either condition, said Kupelian.

Age did not affect the association between nocturia and comorbid conditions. Men and women ages 20 to 64 and 65 or older had a greater mortality risk in the absence of heart disease and diabetes. The only exception was women ages 65 and older, whose mortality risk was lower if they did not have cardiovascular disease.

The study was supported by Ferring Pharmaceuticals.

Disclosure: Kupelian reported no disclosures.

Reference:  Kupelian V et al. “Nocturia and increased mortality risk: Results from the Third National Health and Nutrition Examination Survey” AUA 2010; Abstract 56.