Validity and Reliability of a Questionnaire for Evaluating Nocturia, Nocturnal Enuresis and Sleep-Interruptions in an Elderly Population

ObjectivesTo validate a new questionnaire evaluating nocturia, nocturnal enuresis and sleep-interruptions in an elderly population of men and women in Denmark.MethodsThe Nocturia, Nocturnal Enuresis and Sleep-interruption Questionnaire (NNES-Q) emerged from review of the literature and expert consensus. The questionnaire was a subset of a larger questionnaire comprising several domains on health status and voiding. Convergent and discriminatory validity was assessed in an unselected population of 2000 men and 2000 women 60–80 years old. To test reproducibility, 400 respondents were mailed a separate questionnaire 2 weeks apart. A subgroup of men and women with and without nocturia was used for evaluating reliability of number of nocturia episodes.ResultsA total of 2825 (70.6%) filled in the questionnaire. A decrease in health status was correlated with increasing bother (range: −0.25 to −0.36, p < 0.001, Spearman's r). These findings indicate acceptable convergent validity. Significant discriminatory validity was proven in separate groups of symptom severity (p < 0.0001, Kruskal-Wallis test). Median kappa was 0.70 (range 0.58–0.86) indicating substantial agreement in the retest analysis. Number of nocturia episodes in questionnaires correlated with frequency volume charts (Spearman's rho 0.88; p < 0.001).ConclusionThese data support that the NNES-Q has a good discriminatory and convergent validity, and is reliable over time. The NNES-Q may be useful in epidemiological studies and may also have a potential in daily clinical work up in patients with nocturia and nocturnal enuresis.