Prof. Ian Milsom, Department of Obstetrics and Gynaecology, Sahlgrenska University Hospital, S-416 85 Göteborg, Sweden. e-mail: email@example.com
Objective To determine the prevalence of chronic and debilitating symptoms of the overactive bladder, defined here as the presence of chronic frequency, urgency and urge incontinence (either alone or in any combination), and presumed to be caused by involuntary detrusor contractions.
Subjects and methods Data were collected using a population-based survey (conducted by telephone or direct interview) of men and women aged 40 years, selected from the general population in France, Germany, Italy, Spain, Sweden and the United Kingdom, using a random stratified approach. The main outcome measures were: prevalence of urinary frequency (> 8 micturitions/24 h), urgency and urge incontinence; the proportion of participants who had sought medical advice for symptoms of an overactive bladder; and current or previous therapy received for these symptoms.
Results In all, 16 776 interviews were conducted in the six European countries. The overall prevalence of overactive bladder symptoms in individuals aged 40 years was 16.6%. Frequency (85%) was the most commonly reported symptom, followed by urgency (54%) and urge incontinence (36%). The prevalence of overactive bladder symptoms increased with advancing age. Overall, 60% of respondents with symptoms had consulted a doctor but only 27% were currently receiving treatment.
Conclusion Symptoms of an overactive bladder, of which frequency and urgency are as bothersome as urge incontinence, are highly prevalent in the general population. However, only a few affected individuals currently receive treatment. Taken together, such findings indicate that there is considerable scope for improvement in terms of how physicians diagnose and treat this condition.
Interest in problems of bladder control, e.g. urinary leakage and the overactive bladder, has increased in recent years. This increase has resulted from the heightened awareness of the detrimental effect of LUTS on quality of life, and the activities of the WHO-sponsored First International Consultation on Incontinence . As such, there is a growing demand for the improved management of bladder control problems. In particular, the overactive bladder has become the focus of much ongoing research as a result of the limitations of current therapies for this condition. The overactive bladder is a symptomatic diagnosis and has been defined as comprising the symptoms of frequency (> 8 micturitions/24 h), urgency and urge incontinence, occurring either singly or in combination, which are not explained by metabolic (e.g. diabetes) or local pathological factors (e.g. UTI, stones, interstitial cystitis) [2,3]. Patients with an overactive bladder include those with and without a possible neurological cause for their symptoms. The overactive bladder is a chronic condition defined urodynamically as detrusor overactivity, and characterized by involuntary bladder contractions during the filling phase of the micturition cycle . The involuntary contractions result in reduced functional bladder capacity and unpredictable, troublesome symptoms.
Symptoms suggestive of an overactive bladder often profoundly compromise quality of life [5–7]. The subjective effect of this condition has been objectively measured using the MOS Short-Form 36 generic quality-of-life instrument . These studies showed that patients with bladder overactivity have significantly lower scores in most domains of this instrument than has a normal population. Furthermore, even when comorbidity is controlled for, the quality of life of those with an overactive bladder remains considerably impaired . It is not only episodes of leakage that affect well-being; indeed, frequency and urgency also have considerable detrimental effects on daily activities. Constant worry about when urgency may occur results in the development of elaborate coping mechanisms to enable patients to manage their condition (e.g. voiding frequently in an effort to avoid leakage episodes, mapping out the location of toilets, drinking less, or the use of incontinence pads). It is not difficult to appreciate how these troublesome symptoms may disrupt people's daily lives and occupations. Despite the detrimental effect of these symptoms on quality of life , many affected individuals fail to report this condition to their physicians, and often endure the inconvenience and unpleasantness of symptoms for many years. This may be because they are embarrassed or possibly because of the mistaken opinion that effective treatment is not available. Although the health costs for managing people with an overactive bladder are currently unknown, it is reasonable to assume that they are high, as previous studies report that urinary incontinence alone accounts for ≈ 2% of healthcare costs in Sweden and in the USA [8,9].
To date, there has been no large population-based study to assess the prevalence of the overactive bladder. The large studies conducted have focused on urinary incontinence as a whole [10–15]. Therefore, the aim of this study was to determine the population-based prevalence of overactive bladder symptoms among men and women aged 40 years from six European countries. The level of treatment-seeking and current or previous forms of management received by individuals with these symptoms was also investigated.
Subjects and methods
The survey was carried out by the Sifo/Gallup network in France, Germany, Italy, Spain, Sweden and the UK. Interviews were conducted by telephone, except in Spain, where direct interviews were conducted because of the lower proportion of households having a telephone. A random sample was obtained by a stratified approach based on geographical variables, using information from current telephone number listings or electoral census data (Spain). At least 300 individuals with overactive bladder symptoms were interviewed in each country.
The questionnaire involved a two-stage screening procedure, which first identified individuals with bladder control problems and then characterized the nature of the urinary condition. To minimize bias, the first step was conducted within the context of questions on the occurrence of common health complaints during the previous 12 months. Words such as ‘very frequently’, ‘often’ and ‘several’ were specifically used to define the duration and severity of symptoms. This first step specifically excluded individuals whose only urinary complaint was UTI. Those who reported urinating very frequently during the day, waking up several times at night because of the need to urinate, often feeling a strong need to urinate, or experiencing urinary leakage, proceeded to the next screening stage. In these individuals, detailed symptomatology was determined using a series of key defining questions (Table 1). Symptoms attributable to an overactive bladder were identified by positive responses to specific questions on frequency, urgency and urge incontinence. Frequency caused by an overactive bladder was arbitrarily defined as > 8 micturitions/24 h, given that the normal voiding frequency in healthy individuals is typically ≈ 6 micturitions/24 h [16,17]. For nocturia, the working definition of ‘Have to get up twice or more at night to urinate’ is based on the acceptance that the need to get up once at night to void is normal for older individuals . Although respondents could have more than one overactive bladder symptom, they were only classified once as having an overactive bladder. Positive responses only to voiding symptoms suggestive of stress incontinence, prostatic obstruction, or the occurrence of UTI resulted in exclusion from further investigation.
Table 1. Key defining questions
Urinate > 8 times during the day Have to get up ≥ twice at night to urinate
Have a strong urge to go to the toilet to urinate with no advance warning Have to hurry to get to the toilet in time to urinate
Have to keep running to the toilet to urinate
Am unable to get to the bathroom in time to urinate Have wetting accidents at night while asleep Have a sudden and uncontrolled loss of urine Leak urine during the day without being able to control it
Leak urine while sneezing or laughing Leak urine when exercising or bending over Leak urine when lifting or pulling a heavy object
Even when I feel like I have to urinate I have trouble getting the stream started Have a weak stream when I urinate Experience some dribbling after urinating
Respondents aged 40 years with overactive bladder only or mixed symptomatology were included in this prevalence study. Only those respondents aged 40–74 years were asked further questions about the duration of their symptoms, treatment-seeking, current or previous treatment, and the influence of the disorder on their daily life (given that the interview process proved too lengthy for those aged 75 years in pilot studies). No remuneration was given for participating in the survey.
The same questionnaire was used according to standardized techniques in all countries and was verified for consistency of meaning by back-translation into English. The acceptability and comprehension of the questionnaire was investigated in small pilot studies in Sweden (n = 50) and the UK (n = 25). The final questionnaire was tested in fewer interviews in each country before the main survey was commenced. Data were post-stratified in each country, to match the age and gender distribution. The combined database of the six countries was weighted so that the number of interviews reflected the population size in each country.
The characteristics of the interviewed population (16 776 subjects) are described in Table 2 and the incidence of overactive bladder symptoms in Table 3; ≈ 19% of all respondents reported current bladder symptoms. Overall, symptoms (i.e. frequency, urgency, urge incontinence, alone or in any combination) suggestive of an overactive bladder were reported by 16.6% of respondents, the vast majority (79%) of whom had had their symptoms for at least 1 year and 49% had for > 3 years. The long duration of > 1 year is indicative of symptoms being caused by a chronic condition. Frequency (85%) was the most commonly reported symptom among those with an overactive bladder, followed by urgency (54%) and urge incontinence (36%). The prevalence of individual symptoms occurring alone was small, as was the prevalence of respondents with all the symptoms of an overactive bladder (Fig. 1). The prevalence of overactive bladder symptoms varied among the sample populations of the six European countries studied, ranging from 12% among French and Italian respondents to 22% in the Spanish survey.
Table 2. Characteristics of the 16 776 subjects interviewed
Completed higher education
Don't know/no answer
Unmarried, living with parents
Unmarried, own household
Other/don't know/no answer
Sick leave over a long time
Other/don't know/no answer
Table 3. Prevalence of overactive bladder symptoms in a random sample of the total population aged ≥ 40 years from six European countries
The prevalence of overactive bladder and of all three symptoms (i.e. frequency, urgency and urge incontinence) increased with advancing age (Table 4), and was equally apparent in both men and women (Table 3). There were only minor differences between the sexes in the overall prevalence of an overactive bladder and its symptoms. Thus, the overall prevalence of frequency was ≈ 14% in both men and women; urgency also showed comparable prevalence irrespective of gender. The exception was urge incontinence, which was more prevalent among women than men.
Table 4. Prevalence (%) of overactive bladder symptoms, grouped according to age and gender, in a random sample of 16 776 subjects aged ≥ 40 years from six European countries
Men (n = 7048)
Women (n = 9728)
The number of people aged 40 years with presumed overactive bladder symptoms in the six European countries investigated was estimated based on an extrapolation of the results obtained from this European survey (Table 3). Extrapolation (based on the total population size of each 5-year age group in each country) indicated a total of 22.18 million individuals with overactive bladder symptoms in these six European countries.
In all, 65% of men and 67% of women with an overactive bladder reported that their symptoms had an effect on daily living. Of those individuals aged 40–74 years with an overactive bladder, 60% had consulted a medical practitioner about their symptoms (Fig. 2). Furthermore, almost as many respondents with frequency and urgency alone, compared with those having leakage, had sought help (59% and 66%, respectively). For both men and women, the most common reason given for not seeking help was the belief that no effective treatment was available (61% and 56%, respectively). Only 27% of those who had consulted a doctor were currently taking medication, and a further 27% had tried medication but had stopped taking it. Of all respondents, 62% with overactive bladder symptoms had used coping strategies to manage their symptoms, such as modifying fluid intake or always knowing the location of the toilet. However, only 47% were currently using these methods. Current or previous use of non-medical management strategies, e.g. protective/absorbent products, physiotherapy or pelvic floor exercises, was twice as frequent in women than in men.
The overactive bladder has traditionally been diagnosed on the basis of urodynamic investigation [4,19]. However, the application of such techniques is impractical in large epidemiological studies of the general population. In addition, there is a growing body of opinion in favour of a broader, symptom-based definition of the overactive bladder, encompassing frequency, urgency and urge incontinence occurring in the absence of metabolic or local pathological factors explaining these symptoms [2,3,15]. While clinical experience has shown that these symptoms are highly prevalent, no specific studies investigating the prevalence of bladder overactivity have been published.
The current study is the largest of its kind and the first to report population-based prevalence rates of overactive bladder symptoms. Using a symptom-based approach to diagnosis, the results indicate that overactive bladder symptoms are highly prevalent, occurring in 16.6% of the European population surveyed and estimated to affect a total of 22.18 million individuals in these countries. Importantly, this survey also shows that it is not only the elderly who suffer from the debilitating symptoms of the overactive bladder. Indeed, 43% of respondents with symptoms of this condition were aged 40–64 years. However, it has to be considered that other possible causes of involuntary bladder contractions may have contributed to the prevalence findings, as urodynamic assessments were not used to confirm the underlying cause of these symptoms. In addition, all individuals identified as probably having an overactive bladder in this survey would be candidates for follow-up to exclude possible metabolic or local pathological factors as the reason for their urinary symptoms.
For the purposes of this study an overactive bladder was defined as frequency, urgency and urge incontinence, occurring either singly or in combination, a definition that reflected expert consensus at the time the study was designed. The potential therefore existed for some patients to be experiencing symptoms of frequency alone, which is known to be caused by other reasons than detrusor overactivity . However, in the present survey only 4.5% of respondents had frequency alone. Furthermore, this survey attempted to exclude patients with symptoms caused by acute or transient causes, e.g. UTI. Indeed, the vast majority (79%) of respondents with overactive bladder symptoms had had their symptoms for over a year, and 49% first experienced symptoms > 3 years earlier. In addition, the pattern reported in this paper of the increase in prevalence (in men, increasing slowly up to 69 years, falling slightly, then increasing sharply after 75 years; in women, increasing gradually to 59 years, levelling off between 60 and 69 years, then increasing more dramatically after 70 years) fits closely with that reported in previous studies [10–13,15]. Consequently, the current study presents prevalence data that are as accurate as possible, given the unknown aetiology of this condition and the working definition of the overactive bladder in force at the time the study was designed and conducted.
The variety of definitions used to define bladder control problems, including overactive bladder, has previously made it difficult to compare prevalence data across studies. For example, a meta-analysis of 48 epidemiological studies of urinary incontinence found that prevalence rates vary considerably according to definition . Furthermore, studies were often conducted with no regard to severity, bothersomeness or frequency of symptoms. The current survey questionnaire was specifically phrased to capture symptoms that were considered to be chronic and presumed to be bothersome. Additionally, individuals having symptoms of pure stress incontinence or those suggestive of prostatic obstruction were excluded from the survey, as were those who had UTIs (which are common and transient causes of urinary symptoms). The defining criterion used for urinary frequency (> 8 micturitions/24 h) is somewhat higher than that previously determined for healthy women using a frequency/volume chart (median 5.5 micturitions/24 h) [16,17] and thus gives some indication of the severity of symptoms experienced by individuals included in this survey. Indeed, the vast majority of respondents with overactive bladder symptoms had had their symptoms for over a year, providing further support for the chronic nature of this condition.
The prevalence of overactive bladder symptoms varied among the countries surveyed; the higher values reported in Spain may reflect the method of data collection. In that country, the survey was conducted by direct interview in which respondents may have felt more able to discuss their bladder control problems. Given the low prevalence reported in France and Italy, this method of interview may also be appropriate in these countries. As the precise aetiology of bladder overactivity is unknown, there is no epidemiological evidence to support differences among countries in prevalence rates.
Interestingly, in the current survey the most widely known symptom of the overactive bladder, i.e. urge incontinence, was not the most prevalent. Of those individuals with overactive bladder symptoms, urge incontinence was reported by only 36%. Urinary frequency (i.e. > 8 voids/24 h) was the most common overactive bladder symptom in this population-based sample (85%). This value agrees with previous studies that have reported diurnal frequency to occur in 79–100% of patients with urodynamically verified detrusor overactivity [21,22].
As bladder control problems are common, the questions in this survey were specifically phrased to capture only those symptoms that were chronic and presumed to be troublesome. Moreover, when explicitly asked about the impact of their symptoms, at least 65% of respondents with overactive bladder symptoms reported that their condition adversely affected their daily life. This value is surprisingly high as many individuals with this condition develop coping strategies in an attempt to manage their bladder problems, and may not fully realise the detrimental effect that these symptoms have on their quality of life. These findings clearly indicate that sufferers consider these symptoms to be bothersome and to affect their well-being, complementing earlier reports that the overactive bladder has a profound adverse effect on both subjective and objective measures of quality of life [5–7]. Furthermore, it is not only urinary leakage that respondents find debilitating; frequency and urgency are also considered to be bothersome, because these symptoms are almost as common as urge incontinence as reasons for seeking help.
The consultation rate in the present study was higher than expected (61%), especially considering that, even in the late 1990s (when this study was conducted), many people were still embarrassed by bladder control problems and unwilling to talk about such symptoms. Despite the relatively high rate of consultation, only 27% of those individuals who had sought advice were currently receiving medication. Importantly, of those who did not consult a doctor, many reported that they were unaware that effective treatment was available. Increased public and professional education about the problems of bladder control, and that such problems are treatable or at least manageable, is therefore an important goal for the future .
In summary, this population-based survey confirmed that overactive bladder symptoms are highly prevalent, for which many sufferers appear to have actively sought medical help. Nevertheless, relatively few individuals are currently receiving treatment. In addition to urge incontinence, frequency and urgency are symptoms that should also be taken seriously by physicians as reasons for providing treatment.
This study was funded by the Pharmacia Corporation.
I. Milsom, MD, PhD, Professor of Obstetrics and Gynaecology.
P. Abrams, MD, FRCS, Consultant Urologist.
L. Cardozo, MD, FRCOG, Professor of Urogynaecology.
R.G. Roberts, MD, JD, Professor of Family Medicine.