Characteristics of primary nocturnal enuresis in adults: an epidemiological study


C.K. Yeung, Division of Paediatric Surgery, Department of Surgery, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China.



To evaluate the prevalence and characteristics of primary nocturnal enuresis (PNE) in adults in Hong Kong, as there are currently limited epidemiological data in adults.


After a telephone survey, 8534 respondents (3996 males and 4538 females) aged 16–40 years were selected for the study and stratified in age groups. The questionnaire used comprised two parts; the first started with questions mainly about the general demographic background to decrease the sensitivity of the study and to establish rapport. The second part was conducted through an automated telephone interview service, with the questions being asked by recorded messages and the respondents then keying in their responses with no need to converse with an interviewer. This part included questions about enuretic symptoms and a subjective assessment of social and psychological effects of bedwetting, and measurements of the individual's self-esteem (Rosenberg Self-esteem Scale) and depression (The Centre for Epidemiological Studies Depression Scale).


Of the 8534 subjects interviewed, 196 had PNE, giving an overall prevalence of 2.3% (2.7% males and 2.0% females); of these 196, 36 (18.4%) also had daytime urinary incontinence. Hence, 1.9% of adults (2.2% males and 1.7% females) had monosymptomatic PNE. Of these, 53% wet > 3 nights/week and 26% wet every night. Prevalence rates remained relatively stable among different age groups, with no apparent trend of a reduction with age. Compared with nonenuretic normal controls, significantly fewer enuretics reached tertiary education (33.4% vs 17.8%, P < 0.01). Bedwetters had a significantly higher incidence of depression and lower self-esteem, and a higher incidence of sleep disturbances than the control group. Among bedwetters, 32–40% felt that there was some effect on their choice of job, work performance and social activities, whilst 23% felt the condition affected their family life and in making friends of either sex. However, there was no significant difference in the marital status. Interestingly, only 34.5% of females and half of males used various methods before bedtime to prevent bedwetting.


Overall, 2.3% of Hong Kong adults aged 16–40 years have persistent PNE. Unlike PNE in early childhood the prevalence remained relatively unchanged with age, suggesting that enuretic symptoms persisting into adulthood are probably less likely to resolve with time. Also, significantly more patients had more severe enuretic symptoms. These findings therefore highlight the possibility that PNE in adults may represent a more pronounced form of the condition, and with a more serious social and psychological effect on affected individuals. Further work is needed to evaluate the pathogenesis and management strategy.


(primary) nocturnal enuresis


Self-Esteem Scale


Center for Epidemiologic Studies and Depression (Scale).


Primary nocturnal enuresis (PNE), or bed-wetting, is a very common clinical and a significant social problem in most western countries. From published epidemiological studies it was apparent that although the values vary among different countries the overall prevalence of PNE remains relatively constant irrespective of geographical location. It has been estimated that 20–25% of children by age 4 years and 10% of children by age 7 years are frequent bedwetters [1–5]. In general the prevalence decreases with increasing age. The traditional concept is that most cases are caused by a developmental immaturity of voiding control. Hence many parents and medical practitioners have adopted an expectant or observational approach, assuming that the problem is harmless and will mostly spontaneously resolve as the child ages.

A recent epidemiological study of 21 000 children (aged 5–19 years) in Hong Kong revealed that at 7 years old 10.9% of boys and 9.4% of girls still experience bedwetting [6]. Although the overall prevalence decreased as children became older the proportion of frequent or severe bedwetters who wet > 3 nights/week progressively increased with age. This suggested that the frequent bedwetters might have a significantly higher chance of persistent enuretic symptoms in later life [6]. As persistent enuretic symptoms into adult life may be associated with underlying bladder dysfunction that would require treatment, a more detailed evaluation of the epidemiology and characteristics of nocturnal enuresis in adults is indicated. Thus the aim of the present study was to identify the prevalence of NE in young adults, and to assess any adverse effects of the disorder on the socio-economic and psychological status of affected individuals.


Given the expectation that up to 1–1.5% of young adults in Hong Kong are likely to have NE, and that information from 100 enuretic patients would generate sufficient data for statistical analyses, 13 086 telephone calls were made and the respondents stratified by their age group. Telephone numbers were chosen randomly from the current telephone directory of Hong Kong. Trained interviewers called households between 18.00 and 22.00 hours during weekdays and weekends of the study period, to avoid over-representation of housewives. An unanswered call was attempted at least three times before the telephone number was defined as invalid. Data were collected from only one respondent in each household. If there was more than one eligible potential respondent in the same household the one whose birthday was closest to the date of the interview was interviewed. For those selected respondents who were not at home at least two follow-up calls were made. Subjects were stratified by age into five groups: 16–20, 21–25, 26–30, 31–35 and 36–40 years.

A two-part telephone questioning process was used; the first part (Part I) which contained less sensitive questions was administered by the interviewer. This was important to facilitate the subsequent asking of more sensitive questions. The respondents were told that the second part (Part II) would address some more sensitive questions that were pre-recorded in a computerized phone system, the ‘Infoline service’, which is a popular and widely used telecommunication service offered in Hong Kong for public-opinion polling. Respondents only needed to key in their responses after listening to the pre-recorded questions. Those who agreed to enter the second part of the interview were connected to the automated ‘Infoline service’ by the interviewers. Interviewers left the line once the connection was made.

Part I of the study questioned subjects about their sleeping habits, UTIs and demographic details; Part II questioned about the details of the bedwetting problems, if any. To identify bladder symptoms during the day subjects were also asked about urinary symptoms, including voiding frequency, imperative urgency and incontinence. In addition, their self-esteem and the level of depressive symptoms were also assessed using the Self-Esteem Scale (SES) and Center for Epidemiologic Studies and Depression Scale (CES-D), respectively [7,8]. These elicit information about any possible effects of NE on personal life. Both the SES and CES-D have been used widely to measure psychological well-being, and validated locally in Chinese populations [9–13]. Subjects were also questioned about their knowledge of a family history of bladder control problems.


From our pilot epidemiological studies of PNE in school children, it was estimated that 1.0–1.5% of young adults in Hong Kong aged 16–40 years would be enuretic [6,14], requiring ≈ 13 000 telephone calls to obtain at least 100 subjects for analysis. The control group (normal subjects) was compared with the bedwetting group using a t-test for self-esteem, depression and sleeping habits. A logistic regression analysis, using age group as the independent and NE as the dependent variable (binary) was also applied, presenting relevant odd ratios and their respective 95% CIs, with P < 0.05 considered to indicate statistical significance.


Of the 13086 subjects contacted, 4552 refused immediately to participate in the study when the interviewers stated it was a telephone interview. Among the 8534 subjects (3996 males and 4538 females) who were successfully interviewed, 196 had PNE, giving an overall prevalence of 2.3% (2.7% males and 2.0% females). Thirty-six of the 196 bedwetters (18.4%) also had daytime urinary incontinence. Thus 1.9% of the sample (2.2% males and 1.7% females) had monosymptomatic PNE. Table 1 shows that the prevalence of isolated NE varied little among the different age groups. A logistic regression analysis also showed no effect of increasing age on the resolution of enuretic symptoms. Knowledge of a family member who had experienced NE after adolescence was reported in 13.1% of subjects, the symptom being more common in a sibling than a parent. Enuretic symptoms in these adult subjects were in general more severe than those in children. Of those with NE, 53% wet > 3 nights/week and 26% wet every night. Prevalence rates remained relatively stable among the different age groups with no apparent trend of a reduction with age.

Table 1.  Prevalence of monosymptomatic PNE in adults in Hong Kong with age, education and sleep disturbance
GroupPrevalence, %
  • *

    A, cannot fall asleep; B, wake-up in middle of night; C, wake-up early; D, insomnia.

Age, years16–2021–2526–3031–3536–40
All enuretics2.6 2.2 2.1 2.4 2.2
male3.3 2.2 2.2 2.5 2.8
female1.9 2.3 2.1 2.3 1.7
Education<1 ryF1–4F5F6–7> Univ
Enuretics7.734.240.36.6 11.2
Sleep disturbance* ABCD
Enuretics 49.548.945.439.9
Controls 33.127.433.825.8

All urinary symptoms including voiding frequency, imperative urgency and urge incontinence were significantly more common in subjects with NE than in normal controls (Table 2). Overall, 29.6% of those with NE reported increased daytime urinary frequency and the prevalence increased significantly with age. Urinary urgency was reported in 37.2% of subjects with NE. Daytime urinary incontinence was significantly more prevalent in females than males and was reported overall in 18.4% of affected subjects. The prevalence of both urgency and incontinence was unrelated to age, except in those aged 31–35 years, who had greater daytime urinary incontinence than the other age groups.

Table 2.  Urinary symptoms (%) and the odds ratio (OR) in adult enuretics and controls
GroupVoiding frequencyImperative urgencyIncontinence
No13.5/86.51 15.6/84.41 1.5/98.5 1 
M13.3/86.70.9100.14016.6/83.41.0740.2321.3/98.7 1 
F14.4/85.61 15.7/84.31 2.4/97.6 1.859<0.001
Age group, years
16–2011.6/88.41 15.9/84.111.7/98.31  
21–2512.4/87.61.0740.46615.5/84.50.9710.7331.5/98.5 0.9320.784

Compared with normal controls significantly fewer enuretics reached tertiary education (P < 0.01; Table 1), and significantly fewer with NE or urinary incontinence or urinary frequency reached tertiary education. Furthermore, females with enuresis or incontinence or both reported significantly lower educational levels than their male counterparts. Urinary urgency had not shown such gender bias with education.

Poor arousability whilst asleep is considered to be one of the three main variables associated with NE in children; the present results showed that adults who had NE also had significant sleep disturbances (Table 1). Compared with controls, significantly more adult bedwetters had difficulty entering and staying asleep; besides insomnia, many also complained of early awakening.

Using the SES, scores were significantly lower in subjects with NE than in normal controls (P < 0.05). This difference was most marked in single males with NE, who had significantly lower scores than both male controls and female enuretics (Table 3). In addition, evaluating depression with the CES-D showed that all adults reporting NE had significantly higher depression scores than the controls (P < 0.004; Table 3). However, there were no significant gender or marital status differences. Furthermore, a substantial proportion of subjects with NE felt that it had a significant adverse effect on their social life and career. The most marked psychosocial effect of NE related to the choice of job (40.6%), work performance of employment (33.6%), and participation in social activities (32.5%). Interpersonal and family interactions were least adversely affected by NE (making close friends, 24.6%; family life, 23.2%). There were no significant gender differences in psychological effect. Interestingly, only 34.5% of females and 50% of males had used various methods, including seeking medical advice, to ameliorate their enuretic symptoms.

Table 3.  Self-esteem and depression scores in adult enuretics and controls
Mean (sd) scoreNormalEnureticP
  1. Higher scores indicate higher self-esteem and greater depression.

Male 5.83 (0.77) 5.58 (0.83)<0.05
Female 5.93 (0.72) 5.82 (1.00)>0.05
Total 5.89 (0.74) 5.68 (0.91)<0.05
Male34.24 (7.10)37.88 (8.70)<0.02
Female35.44 (7.33)38.78 (10.3)<0.04
Total34.77 (7.22)38.40 (9.61)<0.01


There are relatively few reports about the problem of PNE in adults; a recent study in the Netherlands sampled > 13 000 adults aged 18–64 years and found an overall prevalence of NE of 0.5%[15]. Based on two earlier studies, most reports have cited a prevalence of 0.7–2%[16,17]. Robertson et al.[18] cited an expectation of identifying NE in ≈ 1% of adults, and indeed this value seems to have been widely accepted. Findings from the current study thus alter this expectation dramatically. Indeed, the 2.3% prevalence of NE among young adults in Hong Kong identified in this study was even slightly higher than the 2.1% reported in community-dwelling older adults aged 65–79 years in the USA [19]. Of interest is that the gender analysis of NE in young adults is similar to that found in children, i.e. consistently more males than females. This differs from that in the older populations, where females report significantly more NE than males [19]. This difference can probably be attributed to secondary rather than primary onset of NE in older adults, and has been shown to be associated with other coexisting medical conditions (e.g. congestive cardiac failure) and their treatment [19].

Findings from the present study further highlight that a significant proportion (53%) of adult enuretics had either moderate or severe forms of enuresis, with wetting > 3 nights/week. This is in considerable contrast with that in children, where most enuretic children have bedwetting episodes less than once per week [1–3,6,20]. It also suggests that PNE in adults may represent a more pronounced and refractory form of the condition that persists from childhood. Results from a recent epidemiological study involving > 20 000 schoolchildren in Hong Kong provide further indirect evidences for this conjecture. The data showed that although the overall prevalence decreased with increasing age, the proportion of patients with severe enuretic symptoms (wetting > 3 nights/week) progressively increased [6]. At age 5 years only 12% of enuretic children wet 7 nights/week, compared with 33% at age 19 (P < 0.01). This suggest that the enuretic children with more severe symptoms might have a significantly higher chance of persistence of NE into adult life [6].

It is now recognized that NE is a heterogeneous disorder with various underlying pathophysiological mechanisms, causing in common a mismatch between nocturnal urine production and bladder capacity during sleep at night, associated with a simultaneous failure of conscious arousal in response to bladder fullness. Recent studies showed that abnormal bladder function, including small bladder capacity, instability during sleep and detrusor hypercontractility caused by BOO, are common among enuretic children with severe refractory symptoms and in whom treatment has failed [15–25]. If our postulation is true that PNE in adults may represent a more pronounced and refractory form of the condition persisting from childhood, then it is possible that many adult enuretic patients may also have some form of bladder dysfunction. Results from the present study showed significantly more urinary symptoms (frequency, urgency and incontinence) suggestive of underlying bladder dysfunction in adults with NE than in controls. Similar findings of urinary symptoms and abnormal bladder function among adult enuretics were reported previously [26–28]. Further study of this group of adults with NE, who in general have more pronounced and persistent symptoms than most affected children, may add to the understanding of the role of bladder dysfunction in the complex pathogenesis of this disorder.

One of the aims of this study was to identify any adverse psychosocial effects of being enuretic as a young adult. Previous studies identified profound psychological and behavioural disorders, poor living conditions and limited life opportunities as being more common among enuretic than nonenuretic children. However, this is the first study to probe educational achievement in adults with NE. Symptoms of NE, incontinence during the day or urinary frequency were all significantly associated with lower educational achievement. However, it remains difficult to confirm whether NE was the direct cause for this finding.

This study also showed that subjects with NE are significantly more likely to have depression. This is similar to the finding in older adults who had secondary onset of NE, as reported by Burgio et al.[19] Self-esteem was also significantly lower in those with NE than in controls. This is not surprising, as similarly low levels of self-esteem were identified in enuretic children [29]. However, once children with NE recovered or responded to treatment self-esteem became normal.

This is the first report to identify significant sleep disturbances in adults with NE; it is likely that there may be a cumulative effect causing fatigue, and an adverse effect on the individual's sense of well-being. Possibly the combination of poor self-esteem, depression and chronic tiredness may contribute to the early discontinuation of education and perceived negative effect of NE on employment and social enjoyment.

In summary, over 2% of adults in Hong Kong have persistent PNE; unlike PNE in early childhood the prevalence remained relatively unchanged with advancing age. This suggests that enuretic symptoms that persist into adulthood are probably less likely to disappear with time, and PNE in adults may represent a more pronounced form of the condition. To date, NE in adults has been poorly investigated and remains a disturbing entity with the potential for profound adverse psychosocial effects. As intervention studies of effective treatment in this population are scarce, the issue of managing adult enuresis warrants further research.


This project was supported by the Health Care and Promotion Fund.