Study type: Prognosis (cohort).

Level of evidence: 2a.

Objective: To investigate, in a population-based study, the association of urinary voiding frequency and daytime wetting or diurnal urinary incontinence (UI) in children aged 6.5 years, to test the hypothesis that children with high or low voiding frequency have increased somatic and psychological risks.

Subjects and methods: Participants were a cohort of > 8000 children enrolled in the population-based Avon Longitudinal Study of Parents and Children, a prospective longitudinal study of an original birth cohort of nearly 14,000 children. Parents completed postal questionnaires asking about diurnal UI, voiding frequency and associated somatic and behavioural signs and symptoms.

Results: In all, 10.4% of children had diurnal UI. Children with diurnal UI had significantly more gastrointestinal, urinary and psychological symptoms than the controls. Of the children with diurnal UI, 35.7% had a voiding frequency of < 5 voids/day, 61.5% 5-9 voids/day and 2.8% > or = 10 voids/day. High voiding frequency was more common in boys, children with frequent diurnal UI and those with combined diurnal and night-time UI, and also in children with nocturia, urgency, hyperactivity and conduct problems. Children with a low voiding frequency needed to be reminded to go to the toilet more often. Fecal incontinence, constipation, stomach 'aches', 'choosy' eating and urinary tract infections were not associated with voiding frequency.

Conclusions: Voiding frequency is an important symptom in children with diurnal UI. The children with high voiding frequencies are especially at risk for associated somatic and behavioural problems.