Overactive bladder: current understanding and future issues

Authors

  • I Milsom

    Corresponding author
    1. Department of Obstetrics and Gynecology, Sahlgrenska Academy at Göteborg University and Sahlgrenska University Hospital, Göteborg, Sweden
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Prof Ian Milsom, Department of Obstetrics and Gynecology, Sahlgrenska University Hospital/Östra, SE-416 85 Göteborg, Sweden. Email ian.milsom@obgyn.gu.se

Interest in problems related to the control of bladder function, such as urinary leakage and overactive bladder (OAB), has increased in recent years. This increase has resulted from the heightened awareness of the human and social implications of lower urinary tract symptoms for the afflicted individual and in particular, the negative impact on quality of life as well as for society in terms of healthcare costs.1 As such, there is a growing demand for an improvement in the understanding and management of bladder control problems. During the 1990s, the OAB, in particular, became the focus of much ongoing research as a result of the limitations of current therapies for this condition.

Definition of the OAB syndrome

The term overactive bladder appeared in the International Continence Society Standardisation of Terminology report from 1988 where it was described as a chronic condition defined urodynamically as detrusor overactivity, and characterised by involuntary bladder contractions during the filling phase of the micturition cycle.2 Later, OAB was also considered as a clinical diagnosis and was suggested to comprise the symptoms of frequency (>8 micturitions/24 hours), urgency and urge incontinence, occurring either singly or in combination which could not be explained by metabolic (e.g. diabetes) or local pathological factors (e.g. urinary tract infection, stones, interstitial cystitis).3,4

In clinical practice, empirical diagnoses are often used as the basis for initial management after assessing the individuals’ lower urinary tract symptoms, physical findings and the results of urinalysis, and other indicated investigations. Thus, the International Continence Society in its Standardisation of Terminology report from 2002 defined the OAB syndrome as urgency with or without urge incontinence, usually with frequency and nocturia.5 These symptom combinations are suggestive of urodynamically demonstrable destrusor overactivity, but can be due to other forms of urethro-vesical dysfunction. The term overactive bladder can be used if there is no proven infection or other obvious pathology.5

In the current International Continence Society (ICS) definition of the OAB syndrome,5 urgency is an obligatory component. This is in line with current opinion6 regarding the importance of urgency as the driving force behind the other components, frequency, nocturia, and incontinence, which are also mentioned in the definition (Figure 1). Urgency is, however, difficult to measure and in many of the clinical trials assessing the pharmacological treatment of the OAB syndrome, micturition frequency has often been used as the primary endpoint as it is easier to quantify.

Figure 1.

Urgency drives the other symptoms of the overactive bladder syndrome. Adapted from Chapple, et al. The role of urinary urgency and its measurement in the overactive bladder symptom syndrome: current concepts and future prospects. BJU Int 2005;95:335–340.6

The OAB—how common is it?

Population studies have previously focussed almost exclusively on urinary incontinence, and there is a wealth of information available in the literature regarding urinary incontinence.7–12 There are at present only a few population-based studies that have assessed the prevalence of OAB.13–15

The prevalence of OAB symptoms was estimated in a large European study involving more than 16 000 individuals.13 Data were collected using a population-based survey (conducted by telephone or face-to-face interview) of men and women aged ≥40 years, selected from the general population in France, Germany, Italy, Spain, Sweden, and the UK using a random, stratified approach. The main outcome measures were prevalence of urinary frequency (>8 micturitions/24 hours), urgency and urge incontinence; proportion of participants who had sought medical advice for OAB symptoms; and current or previous therapy received for these symptoms. The overall prevalence of OAB symptoms in this population of men and women aged ≥40 years was 16.6%. About 79% of the respondents with OAB symptoms had experienced symptoms for at least 1 year and 49% for 3 years. Sixty-seven percent of the women and 65% of the men with OAB symptoms reported that their symptoms had an impact on daily living. The prevalence of OAB symptoms increased with age in both men and women. OAB symptoms were relatively more common in younger women compared with men, while the opposite was found for the older age groups where symptoms were more common in men compared with women. However, when comparing the total population of men and women, there was little difference in the overall prevalence reported in women and men. There were relatively small differences in prevalence between the different countries studied as illustrated in Figure 2, which describes the results grouped according to nationality and sex.

Figure 2.

Prevalence of overactive bladder symptoms in a random sample of the total population aged ≥40 years from six European countries. Adapted from Milsom, et al. How widespread are the symptoms of an overactive bladder and how are they managed? A population-based prevalence study. BJU Int 2001;87:760–766.13

If the prevalence figures obtained in this population-based study are extrapolated to the total population of men and women aged ≥40 years resident in the six countries under investigation, then there will be a total of 22 million men and women with OAB symptoms (Figure 3).

Figure 3.

The prevalence of overactive bladder symptoms in six European countries. Adapted from Milsom, et al. How widespread are the symptoms of an overactive bladder and how are they managed? A population-based prevalence study. BJU Int 2001;87:760–766.13

The prevalence of OAB symptoms has also been assessed in a large population-based survey from the USA. The National Overactive Bladder Evaluation (NOBLE) was designed to assess the prevalence and burden of OAB in the USA. A sample of 5204 adults ≥18 years and representative of the US population by sex, age, and geographical region was assessed.14 The overall prevalence of OAB was similar between men (16.0%) and women (16.9%) and was quite similar to the results reported earlier from Europe.13Figure 4 illustrates the prevalence of OAB grouped according to age and sex in both the European study and the NOBLE study from the USA. The impact of OAB symptoms on quality of life was assessed in a subset of the participants from the NOBLE study. In individuals who reported OAB symptoms, these symptoms had a clinically significant negative effect on quality of life, quality of sleep, and mental health.

Figure 4.

The prevalence of overactive bladder in Europe and the United States. Adapted after data from Milsom, et al. How widespread are the symptoms of an overactive bladder and how are they managed? A population-based prevalence study. BJU Int 2001;87:760–766.13 and Stewart, et al. Prevalence and burden of overactive bladder in the United States. World J Urol 2003;20:327–336.14

The prevalence of OAB was recently studied in a subgroup of women attending a health-screening programme in Sweden.15 Women aged 50–59 years (n= 10 766) were invited to participate and 6917 (64%) responded and attended the screening programme. A total of 3000 women from this health-screening programme (1500 reported urinary incontinence and 1500 did not report urinary incontinence) were specifically questioned about the occurrence of OAB symptoms. The prevalence of OAB symptoms was found to be 46.9% in the group of 50–59-year-old women who reported urinary incontinence and 16.7% in the continent group.

Impact of OAB symptoms on employment, social interactions, and emotional wellbeing

Symptoms suggestive of an OAB often have a profound negative influence on quality of life.14,16–18 The subjective impact of this condition has been objectively measured using the MOS Short-Form 36 generic quality-of-life instrument.17 These studies have shown that people with bladder overactivity have significantly lower scores in most domains of this instrument compared with the normal population. Furthermore, even when comorbidity is controlled for, the quality of life of those with OAB is still considerably impaired.17 It is not only episodes of leakage that affect wellbeing but also urgency and frequency have considerable detrimental effects on daily activities. Constant worry about when urgency is going to strike results in the development of elaborate coping mechanisms to enable people 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 see how these troublesome symptoms may disrupt people’s daily lives and occupations. Despite the negative impact of these symptoms on quality of life,16 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 due to embarrassment or possibly because of the mistaken opinion that effective treatment is not available. People with OAB often try to compensate for their abnormal urinary symptoms by adopting coping behaviours to avoid the feeling of urgency and potential urinary leakage.

The database containing the cross-sectional, population-based survey of people aged 40–64 years in France, Germany, Italy, Spain, Sweden, and the UK (n= 11 521) has been used to evaluate the impact of OAB symptoms on employment, emotional wellbeing, and symptom bother among incontinent versus continent men and women.19 OAB symptoms were identified by a positive response to any question related to urgency, frequency, urge incontinence, or nocturia, which was in accordance with the OAB definition at the time of the survey (Figure 5). Those with complaints indicative of urinary tract infection, stress incontinence or prostatic obstruction were excluded. Respondents were asked questions about the impact that their symptoms had on their emotional wellbeing, social interactions, and productivity at home and at work.

Figure 5.

OAB symptom perception grouped according to gender. Adapted from Irwin et al. Impact of overactive bladder symptoms on employment, social interactions and emotional well-being in six European countries. BJU Int 2006;97:96–100.19

Of those with OAB, approximately 32% reported that having these symptoms made them feel depressed, and 28% reported feeling very stressed. When OAB symptoms were stratified by OAB with incontinence (OAB+) or OAB with no incontinence (OAB−), there were statistically significant differences in reported feelings of emotional stress (OAB+ 36.4% versus OAB− 19.6%) and depression (OAB+ 39.8% versus OAB− 23.3%) (Figure 6). Participants with OAB+ were significantly more likely than those with OAB− to express worry about having accidents and concern about participating in activities away from home because of their bladder symptoms.

Figure 6.

Impact of OAB symptoms on employment grouped according to gender and presence of OAB incontinence symptoms. Percentages are weighted. P < 0.05 for men with OAB with incontinence in each scenario except ‘changed jobs or terminated’. Adapted from Irwin, et al. Impact of overactive bladder symptoms on employment, social interactions and emotional well-being in six European countries. BJU Int 2006;97:96–100.19

In addition, those with OAB+ were significantly more likely to report that these bladder symptoms were a source of great concern and made them feel uncomfortable in social situations compared with those with OAB−. Men were significantly more likely than women to report OAB+ having an impact on their daily work life, including worry about interrupting meetings, impact on decisions about work location and hours, and voluntary termination or early retirement. This effect was primarily in men reporting OAB+. Thus, in conclusion, the study showed that OAB symptoms had a significant effect on the emotional wellbeing and productivity of those affected, both at home and at work.

Treatment-seeking behaviour

The level of treatment-seeking and current or previous forms of management received by individuals with these symptoms were also investigated in the population-based European study assessing the prevalence of OAB (Figure 7).13 The respondents with OAB were asked questions about the duration of their symptoms, treatment seeking, and current or previous treatment.

Figure 7.

The prevalence of medical consultation and current medication in the European Overactive bladder Survey. Adapted from data published by Milsom, et al. The influence of age, parity, oral contraception, hysterectomy and the menopause on the prevalence of urinary incontinence in women. BJU Int 2001;87:760–766.13

Sixty percent of the men and women with OAB had consulted a medical practitioner about their symptoms. Furthermore, almost as many respondents with frequency and urgency alone, compared with those suffering from 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. Sixty-two percent of all respondents with OAB 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 nonmedical management strategies, such as protective/absorbent products, physiotherapy or pelvic floor exercises, was twice as frequent in women compared with men.

The economic burden of OAB

Several studies have described the considerable healthcare costs associated with urinary incontinence.1,20–21 Studies have reported that urinary incontinence alone accounts for approximately 2% of healthcare costs in Sweden and in the USA.1,20 In the UK, between £423M and £535M is spent on incontinence or related urinary symptoms per year.22,23 There is, however, at present less information available about the health costs for the management of people suffering from OAB.

The NOBLE database has been used to estimate the economic costs of OAB, including community and nursing home residents, and to compare the costs in male versus female and older versus younger populations.24 The participants in the NOBLE survey were questioned about work loss and OAB-related health consequences in addition to questions about bladder health symptoms and possible treatment. Survey data estimates were combined with year 2000 average cost data to calculate the cost of OAB in the community. Institutional costs were estimated from the costs of urinary incontinence in nursing homes, limited to only those with urge incontinence or mixed incontinence (urge and stress). The estimated total economic cost of OAB was 12.02 billion dollars in 2000, with 9.17 and 2.85 billion dollars incurred in the community and institutions, respectively. Community female and male OAB costs totalled 7.37 and 1.79 billion dollars, respectively. The authors concluded that the total costs of OAB were comparable with those of osteoporosis and gynaecological and breast cancer.

Future needs

The OAB syndrome is a common symptom complex that affects millions of people worldwide, with an increasing prevalence with increased age.13,14 To manage the large population afflicted, it is imperative to provide readily available services for the management of this common condition. At present, a large proportion of sufferers are not seeking treatment, unaware that effective treatment is available and many who do seek treatment do not obtain effective treatment, and many others who commence therapy do not continue treatment because of adverse effects. To effectively manage the large number of sufferers, it is important to be able to manage uncomplicated cases in primary care, and to this end, the development of guidelines to assist general practitioners in the management of OAB symptoms in primary care is important.

Symptoms of an OAB have been shown to have a negative influence on quality of life as well as being a negative factor for society in terms of healthcare costs. Studies have indicated that OAB has a more negative influence on health-related quality of life than diabetes mellitus, hypertension or asthma17 and affects the quality of life of more men and women than depression.13,25 In the USA, the estimated total economic cost of OAB was 12.0 billion dollars in 2000, and the authors concluded that the total costs of OAB were comparable with those of osteoporosis and gynaecological and breast cancer.24

It is therefore not suprising that the pharmaceutical industry has devoted much efforts into the development of new and more effective drug treatments for OAB. Drugs recently developed have been subjected to assessment in randomised clinical trials against placebo or in some cases, in head-to-head comparisons between major competitors on the market.26–33 The primary endpoint in these trials has been frequency of micturition, and only in the most recent trials has more attention been paid to the symptom of urgency and the influence of OAB symptoms on quality of life. To adequately assess different treatment regimens for the treatment of OAB symptoms, it is essential to develop better means of assessing urgency, which is the only obligatory component of the OAB syndrome and is considered to be the driving force behind the other components, frequency, nocturia, and incontinence.

The mean life expectancy of men and women in the developed world is steadily increasing. In many European countries, there will be a substantial increase in the number of men and women aged ≥65 years by the year 2025.34 As OAB symptoms are more prevalent in the elderly, this change in demographics will result in an increased need for healthcare services and an increase in the number of people requiring treatment. Another important factor to consider regarding the future, apart from the numerical increase in the number of elderly men and women is the fact that many men and women of today suffer in silence, accepting their symptoms as a normal part of the ageing process. Increased awareness regarding the availability of effective forms of treatment will probably result in fewer men and women accepting OAB symptoms as they grow older and increase the need for further development of healthcare services.

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