Epidemiology
Female pelvic floor disorders include urinary incontinence, pelvic organ prolapse, and anal incontinence. These conditions can have a significant impact on a woman’s functioning and quality of life and are associated with limitations that can negatively impact a woman’s wellness and health. With the aging population, female pelvic floor disorders are a significant issue from both an individual and public health perspective. This chapter reviews the epidemiology, risk factors, and the psychosocial impact of these conditions.
Urinary Incontinence
In general, urinary incontinence can be characterized by the presence of specific symptoms, frequency of urine leakage, severity of leakage, degree of bother to the woman, and type of incontinence. Prevalence and incidence rates can vary widely depending on the definition used, as well as measurement and survey methods and population differences.
Prevalence
Prevalence rates reflect the total number of cases of disease in the population at a given time. For urinary incontinence, definitions used in the literature range from using the presence of leakage (yes/no) to using the frequency of leakage (daily, weekly, monthly, ever) to using symptom bother to determine prevalence. Therefore, it is important to qualify what specific definition was used when reporting prevalence and incidence rates.
A review of 21 studies by found the average prevalence of any incontinence for older women was 34%, and 12% for daily incontinence. For middle-aged and younger adults, the average prevalence of any incontinence was slightly lower at 25% in the same study. analyzed the National Health and Nutrition Examination Survey (NHANES) and used a more strict definition, defining incontinence as “at least weekly leakage or monthly leakage more than drops.” Based on this definition, the authors reported a prevalence of 15.7%. Also using NHANES data, reported a prevalence of 51% when incontinence was defined as any positive response. Table 7.1 summarizes the prevalence of urinary incontinence based on age group and varying definitions.
| Author | Definition Used | Prevalence (%) |
|---|---|---|
| All Ages | ||
| At least weekly leakage or monthly leakage more than drops | 15.7 | |
| Any leakage | 51.1 | |
| Middle Ages | ||
| (ages 40-59) | At least weekly leakage or monthly leakage more than drops | 17.2 |
| (ages 42-52) | At least monthly incontinence | 46.7 |
| (ages 40-59) | Any urine loss | 13.7 |
| Older Ages | ||
| (ages 60 and older) | At least weekly leakage or monthly leakage more than drops | 23.3-31.7 |
| (ages 60 and older) | Any urine loss | 20 |
Prevalence rates also vary based on symptom severity. Again using NHANES data, reported that the prevalence of any urinary incontinence in women aged 50 to 59 was 19.9% for “mild” incontinence, 16.5% for “moderate” incontinence, and 25% for “severe” incontinence. Variable prevalence rates were also seen in other age groups based on symptoms severity.
The type of urinary incontinence is also important when considering the prevalence of the condition ( Fig. 7.1 ). The prevalence of stress urinary incontinence ranges from 33% to 54%, urge urinary incontinence ranges from 12% to 16%, and mixed urinary incontinence ranges from 19% to 50% in populations reporting any incontinence. Similar data are available from multiple countries documenting that these conditions are highly prevalent worldwide.
Incidence, Remission, Improvement, and Progression
Urinary incontinence is a dynamic condition and symptoms may wax and wane. Incidence rates reflect the number of new cases of disease in the population during a specified period of time. The average one-year incidence ranges from 6.9% to 11.1% in the United States in women younger than 55 years ( ). The rate is higher in older women, estimated to be 13.8% over 1 year in women 54 to 79 years of age. Remission, improvement, and progression data are more limited. Reported 1-year remission rates range from 4.6% to 9.1% ( ). Improvement rates range from 4.5% to 16% over 1 year and one study estimated that symptom progression rate is 16%.
Urinary Incontinence during Pregnancy and Postpartum
Stress urinary incontinence is common during pregnancy with a prevalence ranging from 40% to 59%. In general, the severity may worsen throughout pregnancy. In postpartum women, stress urinary incontinence will resolve in many, and the prevalence is estimated to range from 15% to 30% ( ). In longitudinal studies, the cumulative incidence rate of urinary incontinence is estimated to be approximately 39% ( ). Up to 26% of women who reported urinary incontinence during pregnancy will have persistent leakage in the postpartum period; the majority will have resolution. Of those with persistent leakage, 47% will report moderate to severe symptoms.
Costs
The financial burden of urinary incontinence and overactive bladder syndrome is significant and includes direct and indirect costs. Direct costs include costs to the patient for routine care (absorbent products, laundry), medical visits, and treatments. Indirect costs include loss of productivity and costs of paid or unpaid caregivers, which are more difficult to measure ( Table 7.2 ). Many studies support that the largest cost item associated with urinary incontinence for both community-dwelling women as well as those in nursing homes remains routine care and supplies, with only a minimal proportion of the costs going to evaluation and treatment. Although most studies evaluate the direct costs due to accessibility of data, the economic impact of indirect costs should not be underemphasized.
| Type of Cost | Examples |
|---|---|
| Direct Costs | |
| Diagnostic and evaluation costs | Physician consultation and evaluation, laboratory, diagnostic procedures |
| Treatment costs | Surgery, medication, pelvic/behavioral therapy |
| Routine care costs | Nursing labor, supplies, laundry |
| Rehabilitation costs | Nursing, supplies |
| Incontinence consequence costs | Skin breakdowns, urinary tract infections, falls, nursing home/assisted living care |
| Indirect Costs | |
| Costs of unpaid caregivers | Time, loss of work |
| Loss of productivity | Missed time from work for diagnosis/treatment, missed time from work due to morbidity |
A study by estimated that the annual direct cost of urinary incontinence for women was $12.4 billion (2001 U.S. dollars) and the largest cost category was routine care (70% of costs), followed by nursing home admissions (14%), treatment (9%), complications (6%), and diagnosis and evaluation (1%). Medicare spending on incontinence treatment continues to increase dramatically. For Medicare beneficiaries aged 65 and older, used multiple national databases and reported that the expenditures for inpatient and outpatient medical care doubled from $128 million in 1992 to $234 million in 1998. They also estimated that 23% of incontinent women missed an average of 28.7 h of work due to inpatient and outpatient care associated with urinary incontinence treatment.
At the individual level, annual routine costs alone are estimated to be $250 to $900 per woman in 2005 ( ). Direct costs for incontinence management increase significantly with greater incontinence frequency. evaluated the impact of incontinence improvement on incontinence-associated costs and found that the mean cost for an individual decreased by 23% for each decrease of seven incontinence episodes per week. Because most of the cost associated with incontinence care is out of pocket, patients assume great financial responsibility in managing this condition.
Pelvic Organ Prolapse
Similar to incontinence, definitions for pelvic organ prolapse are also variable. The International Continence Society (ICS) defines prolapse as the descent of one or more of the anterior vaginal wall, posterior vaginal wall, and the apex of the vagina or vault. Most epidemiologic studies define prolapse based on either physical examination findings or patient symptom report.
Prevalence, Incidence, Remission, and Progression
Most population-based surveys define prolapse based solely on patient symptoms, commonly defined as an affirmative response to seeing/feeling a vaginal bulge. Using this definition, the prevalence of prolapse symptoms ranges from 2.9% to 8% in the United States ( ). These studies did not include physical examination information. Additional studies from the Women’s Health Initiative (WHI) including U.S. women aged 50 to 79 years found the prevalence of any degree of prolapse based on examination alone of grades 1 to 3 prolapse to be 41.1% ( ). Table 7.3 presents the estimated prevalence of prolapse based on physical examination for various compartments. These studies did not include patient symptom information. Prevalence estimates based on exam findings alone are higher compared to those based on symptom reports alone.
| Study | Definition of Prolapse | Prevalence |
|---|---|---|
| Exam only | Stage 0 = 24% | |
| Stage 1 = 38% | ||
| Stage 2 = 35% | ||
| Stage 3 = 2% | ||
| Exam only | Any prolapse = 41.1% | |
| Cystocele = 34.3% | ||
| Uterine = 14.2% | ||
| Rectocele = 18.6% | ||
| Exam only | Cystocele = 24.6% | |
| Uterine = 3.8% | ||
| Rectocele = 12.9% | ||
| Symptoms only | 5.70% | |
| Symptoms only | 2.90% | |
| Symptoms only | 11.40% |
Data are limited for the incidence and remission of pelvic organ prolapse. Based on the WHI data, incidence of grades 1 to 3 prolapse are estimated to be 9.3/100 women-years for cystocele, 5.7/100 women-years for rectocele, and 1.5/100 women-years for uterine prolapse. The remission rates are estimated to be up to 9%, with cystocele having higher remission rates than rectocele. Prolapse progression ranged from 1.9% for uterine prolapse, to 9.5% for cystocele, and 14% for rectocele. Older, parous women are more likely to develop new or progressive prolapse than to regress. Progression and resolution appear to be dependent on baseline severity of prolapse.
After pregnancy and delivery, 31% of women have stage II prolapse. After delivery, 14% to 15% of women have prolapse at or below the hymen and 5% have this after cesarean delivery.
Costs
The direct cost of pelvic organ prolapse surgery in 1997 was estimated to be $1012 million based on national average Medicare reimbursement. Physician services accounted for 29% and hospitalization accounted for 71% ( ). There are few data on the indirect costs or direct patient costs of pelvic organ prolapse.
Anal Incontinence
Prevalence, Incidence, and Remission
Anal incontinence includes the involuntary passage of gas, mucus, liquid, or solid stool. The prevalence and epidemiology of anal incontinence has been poorly documented, and many women are too embarrassed to report the condition. Most epidemiologic studies define anal incontinence as any involuntary leakage of stool. Depending on the definition used, the prevalence of fecal incontinence in U.S. women ranges from 2.2% to 24%. When defined as any leakage in the past year, the prevalence is estimated to be approximately 24% ( ). When defined more frequently as at least monthly leakage, the prevalence is estimated to be approximately 9% ( ).
estimated the prevalence of different types and frequencies of fecal incontinence in noninstitutionalized U.S. women using NHANES data. The overall prevalence of fecal incontinence within the past month was 8.9%, and increased with age from 2.6% in 20 to 29-year-olds to 15.3% in women 70 years and older. The most common type of incontinence was with watery/liquid stool (>20%), followed by hard and normal stool (approximately 9% for both). Fifty-one percent of women reported leakage of gas in the past month and 21% reported at least daily leakage of gas.
Data regarding the incidence, regression, and progression of anal incontinence are extremely limited. estimated the incidence and remission of fecal incontinence in Medicare beneficiaries. Defining fecal incontinence as any loss of bowel control during the previous year, the incidence rate at four years was approximately 18% in women and the remission rate was 57%. The overall incidence rate for the development of more severe fecal incontinence, defined as monthly or greater incontinence, was 6.3%.
Anal Incontinence during Pregnancy and Postpartum
During pregnancy, up to 10% of women present with anal incontinence, and the cumulative incidence rate is estimated to be 10.3% ( ). Of the women reporting anal incontinence during pregnancy, 29.7% reported persistent anal incontinence postpartum.
Costs
reported the average lifetime cost to be approximately $17,166 per patient for treatment, follow-up, physician evaluation, and costs for protective materials in 1996, and average surgical costs were $8555 per procedure. estimated the hospital cost of inpatient surgery alone for female fecal incontinence to be $6000 per surgical admission in 2003, totaling $24.5 million spent on hospital costs for surgery alone that year. This estimate did not include direct costs of physician services or any indirect costs.
Coexisting Pelvic Floor Disorders
Pelvic floor disorders often coexist in the same woman. In community-dwelling women, 23.7% report symptoms of one or more pelvic floor disorders. By specific condition, the co-occurrence of having at least one other pelvic floor disorder is 80% in women with stress incontinence or overactive bladder, 69% with pelvic organ prolapse, and 48% with anal incontinence. Fifty-six percent of women report both stress incontinence and overactive bladder, 58% report both stress incontinence and anal incontinence, 56% report overactive bladder and anal incontinence, and 29% report pelvic organ prolapse and any incontinence ( ).
Future Projections
It is projected that future demands for ambulatory care and surgical treatment for female pelvic floor disorders will increase. estimated the increase in number of women who will be affected by pelvic floor disorders through 2050 using NHANES prevalence rates and U.S. Census Bureau projections. Using these methods, the authors estimated that the number of American women with at least one pelvic floor disorder will increase from 28.1 million in 2010 to 43.8 million in 2050. During this time period, the number of women with urinary incontinence will increase 55% from 18.3 million to 28.4 million. Fecal incontinence will increase 59% from 10.6 million to 16.8 million, and the number of women with prolapse will increase 46% from 3.3 million to 4.9 million. The highest estimated projections for 2050 estimate that 58.2 million women will be affected by at least one pelvic floor disorder.
Using estimated surgical rates in national databases and population projections from the U.S. Census Bureau from 2010 to 2050, project that the total number of women who will undergo stress urinary incontinence surgery will increase almost 50% from 210,700 in 2010 to 310,050 in 2050. Similarly, the total number of women who will undergo prolapse surgery will increase from 166,000 in 2010 to 245,970 in 2050. These estimates assume that the rates of surgery will remain unchanged.
Causes and Prevention of Pelvic Floor Disorders
Causes of pelvic floor disorders are multifactorial, and it is difficult to understand the relative importance of each factor for a specific individual or population. However, it is useful to understand the impact of each factor on the development of pelvic floor disorders to potentially aid in disease prevention.
Race
The role of race as a predisposing risk factor for pelvic floor disorders remains unclear. Though some studies report that white women are at increased risk for stress urinary incontinence ( ), symptomatic pelvic organ prolapse ( ), and fecal incontinence ( ) this is not a consistent finding. specifically evaluated urinary incontinence prevalence among major racial and ethnic groups and found that the prevalence of all types of incontinence was highest in Hispanic women (36%), followed by white (30%), black (25%), and Asian (19%) women. also reported that a significantly higher proportion of white women reported stress incontinence compared to black women (39% versus 25%). However, two other studies found no difference in pelvic floor disorders among racial/ethnic groups ( ). A large epidemiologic study assessing fecal incontinence symptoms also found no difference by race ( ).
Differences in physiologic makeup may predispose some racial and ethnic groups to pelvic floor disorders. MRI measurements of bony architecture and soft tissue show that white women have a wider pelvic inlet, wider outlet, and shallower anteroposterior outlet than African American women ( ). When compared to white women, African American women also demonstrated a 29% higher average urethral closure pressure during a maximum pelvic muscle contraction ( ).
Age
There is a significant increase in the prevalence of pelvic floor disorders by age, increasing from 9.7% (95% CI, 7.8%-11.7%) in women aged 20 to 39 years, to 26.5% (95% CI, 23.0%-29.9%) in women aged 40 to 59 years, to 36.8% (95% CI, 32.0%-41.6%) in women aged 60 to 79 years, to 49.7% (95% CI, 40.3%-59.1%) in women aged 80 years or older ( P < 0.001; ). For urinary incontinence, the prevalence increases from 17% to 32% for women aged 40 to 59 years versus women over 80 years of age. reported that for anal incontinence, the prevalence increases from 2.6% at ages 20 to 30 years to 15.3% in people aged 70 years or older.
Familial and Genetic Linkage
Epidemiologic evidence suggests that family history of prolapse is a risk factor for disease, and a meta-analysis including eight studies with over one thousand prolapse patients showed that women with prolapse are more likely to have family members with the same condition when compared to controls ( ). Family based studies have shown there is an autosomal dominant inheritance of pelvic floor disorders. In addition, candidate gene studies, expression studies, and linkage studies have all been suggestive of a genetic contribution to pelvic organ prolapse ( ).
Candidate gene studies have focused on collagen and elastin biosynthesis, extracellular matrix metabolism, and hormone receptors. For example, it is understood that collagen is one of the main constituents of the connective tissue in the pelvic floor, with type I collagen being well organized, and type III collagen being common in loose areolar tissue. In histologic studies, higher levels of type III collagen have been found in pelvic floor connective tissue for women with pelvic organ prolapse ( ). In candidate gene studies, it appears that gene expression of the gene that encodes the chains of type III collagen may be variable and therefore put women at higher risk for pelvic organ prolapse ( ).
Childbirth
Perhaps secondary to increased abdominal pressure and/or connective tissue changes, pregnancy itself has been shown to be a risk factor for pelvic floor disorders. However, the major inciting factor for pelvic floor disorders in parous women is likely childbirth. reported that the proportion of women reporting at least one pelvic floor disorder increased incrementally with parity: 12.8%, 18.4%, 24.6%, and 32.4% for 0, 1, 2, and 3 or more deliveries, respectively ( P < 0.001).
To further evaluate the association between pelvic floor disorders and mode of delivery, conducted a longitudinal cohort study following women for 5 to 10 years from first delivery. When compared with cesarean delivery without labor, spontaneous vaginal birth was associated with higher odds of stress incontinence (OR 2.9 (95% CI, 1.5-5.5)) and prolapse at or beyond the hymen (OR 5.6 (95% CI, 2.2-14.7)). Operative vaginal deliveries and perineal lacerations have also been associated with pelvic floor disorders. reported that women with anal sphincter injuries after vaginal delivery were twice as likely to report postpartum fecal incontinence compared to women without sphincter tears.
Regarding potential mechanisms of injury after vaginal delivery, found that women with prolapse have more frequent defects in the levator ani muscles and generate less vaginal closure force during a maximal contraction than controls. In a study using four-dimensional translabial ultrasound and pelvic exam, it was found that women with levator ani avulsion defects had an increased risk of stage II or higher pelvic organ prolapse ( ). This association was strongest for cystocele (RR 2.3, 95% CI, 2.0-2.7) and uterine prolapse (RR 4.0, 95% CI, 2.5-6.5).
Constipation
Constipation and straining associated with constipation has been associated with pelvic organ prolapse. Indeed, many providers may counsel patients to avoid constipation and related straining at stool to reduce the risk of prolapse. However, whether the association between constipation and prolapse is causal remains unclear. There are variable definitions of constipation as well as the use of nonspecific definitions for bowel function disorders. In addition, treatments of prolapse, including rectocele repair and sacral colpopexy, have variable results on improving and/or resolving constipation and bowel symptoms.
Obesity
Increased body mass index (BMI) is a risk factor for pelvic floor disorders. Many studies have shown that obesity is a risk factor for urinary incontinence. In addition, several studies have shown that both stress and urge incontinence improve when patients lose weight through lifestyle changes and/or bariatric surgery ( ). In a clinical trial of women randomized to an active weight loss program compared to educational materials, weight loss was associated with improvements in incontinence episodes among overweight and obese women ( ).
A cross-sectional study of postmenopausal women who enrolled in the WHI Hormone Therapy Clinical Trial found an increased risk of prolapse in women with a BMI of 25 or higher ( ). To further understand the longitudinal effects of obesity on prolapse, performed a secondary analysis of the WHI data to evaluate the relationship between change in weight and prolapse progression/regression in postmenopausal women during a 5-year period. They found being overweight or obese was highly associated with the progression of prolapse when compared to women with a healthy BMI. However, weight loss was not associated with prolapse regression.
With regards to anal incontinence, found prevalence rates to be high among morbidly obese women compared to the general population. In looking at the effect of weight loss surgery on fecal incontinence, bariatric surgery in morbidly obese women was associated with a decrease in fecal incontinence (solid or liquid stool) from 19.4% to 9.1% at 6 months and 8.6% at 12 months ( P = 0.018; 95% CI, 2.1-19.4%) ( ).
Smoking
Several studies suggest a positive association between smoking and urinary incontinence. A large population-based study, the Norwegian Epidemiology of Incontinence in the County of Nord-Trøndelag (EPINCONT) study, investigated the association between modifiable lifestyle factors such as smoking and urinary incontinence. In this study both former and current smoking was associated with incontinence, limited to those women who smoked 20 cigarettes a day or who had a 15-year pack history, suggesting a dose-response relationship ( ). The EPINCONT study found that the effect of smoking on incontinence was reduced after adjusting for coughing and dyspnea; however, there was a persistent effect from smoking not mediated by airway disorders.
Menopause/Hormone Replacement Therapy
The female genital tract and the lower urinary tract arise from the same embryologic origin and thus are both sensitive to the effects of sex hormones. Transition to a hypoestrogenic state during menopause leads to changes in the vaginal and urethral mucosa. This could theoretically impact the development of incontinence. reported on a population-based cohort of women who experienced menopausal transition and found no association with the development of urinary incontinence. This is consistent with other epidemiologic studies that have not found an association between the onset of menopause and an increase in urinary incontinence. It is possible that the effects of a hypoestrogenic state may not be apparent in the first few years. In addition, menopause is associated with age, making it difficult to separate any independent effects of hormonal changes and aging.
Although systemic vaginal estrogen was in the past often promoted as beneficial for lower urinary tract symptoms, more recently the role of estrogen has become less clear. In the HERS study, exogenous estrogen and progesterone were associated with worsening incontinence (39% versus 27%, P = 0.001). This was evident by four months of treatment and true for both urge and stress incontinence symptoms ( ). Similarly, in the WHI, found that exogenous hormone therapy increased the risk of all types of urinary incontinence at 1 year in women who were continent at baseline. They found that the risk was highest for stress incontinence (estrogen and progesterone: RR, 1.87 (95% CI, 1.61-2.18); estrogen alone: RR, 2.15 (95% CI, 1.77-2.62)), followed by mixed incontinence (estrogen and progesterone: RR, 1.49 (95% CI, 1.10-2.01); estrogen alone: RR, 1.79 (95% CI, 1.26-2.53)). They also found that menopausal hormone therapy worsened the severity of incontinence among symptomatic women after 1 year.
Recently, The Cochrane Incontinence Review Group summarized all studies up to June 2012 ( ). They concluded that urinary incontinence may be improved with the use of local estrogen treatment, although long-term effects are unknown. Conversely, systemic hormone replacement therapy using conjugated equine estrogen may worsen incontinence. There are too few data to reliably address other aspects of estrogen therapy, such as estrogen type and dose, and no direct evidence comparing routes of administration. The risk of endometrial and breast cancer after long-term use of systemic estrogen suggests that treatment should be for limited periods, especially in those women with an intact uterus.
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