Nocturia frequency, bother, and quality of life: how often is too often? A population-based study in Finland

Nocturia (ie, waking at night to void) is common and disrupts sleep. Traditionally, one nightly episode has been regarded as clinically meaningless, yet the justification for this belief remains weak.

To evaluate the association among frequency of nocturia and bother and health-related quality of life (HRQoL).

In 2003-2004, a survey was mailed to a random sample of 6000 subjects aged 18-79 yr who were identified from the Finnish Population Register Centre (response proportion was 62.4%; 53.7% were females).

HRQoL and bother from nocturia were examined in relation to self-reported nocturia frequency (using the American Urological Association Symptom Index and the Danish Prostatic Symptom Score). Bother from nocturia was assessed on a four-point scale (none, small, moderate, major). HRQoL was measured with the generic 15D instrument on a 0-1 scale with a minimum clinically important difference of 0.03.

Degree of bother increased with nocturia frequency (p<0.01). The most commonly cited degree of bother for those with one, two, and three nightly voids was no bother, small bother, and moderate bother, respectively. The mean age-adjusted 15D score for men (and women) without nocturia was 0.953 (0.950) and 0.925 (0.927) with one void per night, 0.898 (0.890) with two voids per night, and 0.833 (0.840) with three or more voids per night. Statistically significant decreases were found in 15D score and in all 15D dimensions except eating. Although the response rate was high, approximately one third of those contacted did not participate in the study.

At least two voids per night is associated with impaired HRQoL. The majority of people report having bother when the number of nocturia episodes is two and moderate or major bother when the number is three or more. One void per night does not identify subjects with interference from nocturia and, thus, is not a suitable criterion for clinically relevant nocturia.