Objective: To evaluate any differences in the characteristics of primary nocturnal enuresis (PNE) between younger enuretic children and adolescents.
Subjects and methods: In all, 21 000 questionnaires designed to determine the presence or absence of bed-wetting, diurnal incontinence, frequency of wetting, systemic illness, and family history, were sent to children aged 5-19 years from 67 kindergartens, primary schools and secondary schools randomly selected by a computer from different areas in Hong Kong. In addition, questions were asked to evaluate when and how the parents became aware that bed-wetting is a significant medical problem deserving attention in children after the age of 5 years.
Results: Of the 21,000 questionnaires distributed, 16 512 (78.6%) were completed. Among the respondents, 512 children (302 boys, 210 girls) had PNE; of these, 106 (20.7%) also had daytime incontinence. There was a marked reduction in the overall prevalence of PNE with advancing age. At 5 years old, 16.1% of children had PNE (20.7% boys, 10.8% girls; at age 9 and 19 years, 3.14% and 2.2% of children had PNE, respectively. However, this reduction was significantly more apparent among those with mild enuretic symptoms (wet <3 nights/week) than in those with more frequent bed-wetting. Furthermore, younger enuretic children behaved very differently from adolescents and older patients. As age increased there was a significant tendency towards more severe enuretic symptoms. At age 5 years, 14.3% of enuretic children wet 7 nights/week, compared with 48.3% at age 19 years (P < 0.001). In addition, significantly more adolescent boys aged >10 years had daytime urinary incontinence than had enuretic children aged < or = 10 years (32% vs 14.6%, respectively, P < 0.001). Most (89%) parents only became aware that bed-wetting was a significant medical problem deserving attention through material in the mass media over the past 3-4 years.
Conclusions: The present finding suggesting that PNE spontaneously resolves with increasing age probably applies only to those with mild enuretic symptoms. There are significant differences in characteristics between younger enuretic children and older subjects. As age increases there is an increasing proportion of enuretic patients with more severe bed-wetting. Enuretic children aged >10 years and adolescents have significantly more daytime urinary symptoms and incontinence. The previously reported low prevalence of PNE in Hong Kong was probably due to parental indifference to the problem.