Usefulness of nocturia as a mortality risk factor for coronary heart disease among persons born in 1920 or 1921

Abstract

Cardiovascular events are clustered in the morning hours, after increases in blood pressure and heart rate that accompany awakening and arising. Similar hemodynamic changes occur during the night after nocturnal awakening and getting up. Such changes are common among older patients who have nocturia frequently and rise to urinate. We tested the hypothesis that nocturia may be associated with increased mortality in a population sample of 456 subjects born from 1920 to 1921, examined in 1990, and followed for total mortality until 2002. At baseline, they were questioned about nocturia (> or =2 times at night) as part of a detailed questionnaire and examination. Twelve-year survival was significantly lower (61% vs 72%, p = 0.0206) among subjects reporting nocturia (n = 160, 64% men) compared with those without nocturia (n = 296, 50% men). After accounting for numerous confounders, a proportional hazard model determined the mortality hazard ratio (HR) for nocturia alone to be 0.89 (95% confidence interval [CI] 0.55 to 1.43). The interaction between nocturia and previous coronary heart disease (CHD) was highly significant (p <0.0001), with an interaction variable HR of 2.16 (95% CI 1.01 to 4.61). Survival of patients who had CHD with nocturia (n = 54) versus those without nocturia (n = 65) was 44% versus 66% (p = 0.0201). Among patients with CHD, the mortality HR for nocturia was 2.11 (95% CI 1.16 to 4.00). In conclusion, nocturia is a significant independent predictor of mortality among 70-year-old patients with known CHD and thus warrants special attention.