These data represent the first nationwide, population-based estimates of the 3 primary pelvic floor disorders in women in the United States derived from a single source. Nearly one-quarter of all women and more than one-third of older women reported symptoms of at least 1 pelvic floor disorder. By 2030, more than one-fifth of women will be 65 years or older.8
As the population of older women increases, the national burden related to pelvic floor disorders in terms of health care costs, lost productivity, and decreased quality of life will be substantial. Furthermore, our prevalence estimates are likely underestimates for several reasons: (1) they do not reflect symptoms of women who have undergone successful treatment for pelvic floor disorders; (2) we used conservative definitions; and (3) symptom-based diagnosis underestimates the true prevalence of pelvic organ prolapse diagnosed by physical examination.
Other studies, including data from NHANES in earlier waves,9–13
concluded that between 25% and 75% of women have urinary incontinence, depending on how the condition is defined. Higher rates represent a symptom of occasional leakage, while lower rates are more likely to represent a disease. We limited our definition to those women with moderate to severe leakage to better reflect the population of women more likely to seek treatment.
Similarly, published estimates of the prevalence of fecal incontinence in the community range widely, from 2.2%14
up to 24%.15–18
As with urinary incontinence, differences in prevalence estimates are explained in part by differences in case definition, with some studies including involuntary loss of flatus in the definition and other studies limiting the definition to loss of stool or mucus.
Population-based epidemiological studies of pelvic organ prolapse are rare, despite the fact that it is a common indication for gynecologic surgery in older women. A major impediment to population-based studies is the requirement of an examination to assess vaginal support. Several studies,19–21
including our study, avoided this limitation by screening for prolapse based on the presence of prolapse-related symptoms rather than examination. The symptom most strongly correlated with the presence of advanced pelvic organ prolapse is “seeing” or “feeling” a vaginal bulge.22–25
There is no clear consensus about what level of prolapse represents a variation of normal uterovaginal support and what represents disease, although there is growing consensus that prolapse beyond the hymen is more likely to be clinically significant.22,25
Up to 75% of women presenting for routine gynecological care demonstrate some prolapse, and 3% to 6% have descent beyond the hymen.26,27
The specificity of vaginal bulge symptoms for predicting prolapse beyond the hymen is high in low-prevalence populations (99%–100%); however, the sensitivity is low (16%–35%), because some women with even advanced prolapse deny symptoms.7,25
Thus, prolapse prevalence in studies using symptom-based screening such as this one underestimate the true prevalence of anatomic disease. However, because women typically do not seek care for prolapse until symptoms develop and physicians generally do not offer surgical treatment until symptoms become bothersome, symptom-based prevalence estimates likely represent the best estimate of disease burden on the population.
The finding that both urinary and fecal incontinence increase with age is consistent with the epidemiological literature.28–30
The few studies available show that apical, anterior, and posterior vaginal wall prolapse also increases with advancing age.31–33
The relationship between pelvic floor disorders and age is usually attributed to age-related connective tissue and neuromuscular changes and to comorbidities, such as obesity, pulmonary disease, and diabetes, that occur more commonly among older adults.
Consistent with prior studies, these data demonstrate a significant association between childbirth and pelvic floor disorders. In the Oxford Family Planning Study,33
women with 2 deliveries were substantially more likely to have surgery for prolapse compared with women with no delivery. In a cross-sectional study of Norwegian women, compared with women with no deliveries,34
the effect of 2 or more deliveries on urinary incontinence was greatest in younger women aged 20 to 34 years (relative risk [RR], 2.8; 95% CI, 2.3–3.3), decreased among women aged 35 to 64 years (RR, 2.0; 95% CI, 1.6–2.3), and then, consistent with other literature, was not associated with urinary incontinence in women older than 65 years. The association between fecal incontinence and parity is inconsistent.35,36
However, the fact that more than 1 in 8 nulliparous women in the 2005–2006 NHANES reported at least 1 symptomatic pelvic floor disorder demonstrates the multifactorial nature of these conditions.
In contrast with several other large studies in which white women had a higher prevalence of urinary incontinence and pelvic organ prolapse than did black or Hispanic women,11,37–40
we found no difference in prevalence in comparisons of black, non-Hispanic white, or Hispanic women. We did not categorize urinary incontinence by subtype (stress or urge) in this analysis, which may account for this difference. A recent analysis using earlier NHANES data (2001–2004) found a higher prevalence of stress urinary incontinence in white and Mexican American women than black women, but no differences in other incontinence subtypes.41
Although national hospital discharge statistics show that black women have lower rates of prolapse surgery than white women,41
this difference cannot be attributed to just race. Many factors, including access to care, contribute to the decision to undergo surgery, and therefore to surgical prevalence rates. Because we have no information about treatment for pelvic floor disorders, we cannot comment on whether treatment varies by race/ethnicity in our sample. Although Hispanic women were less likely than white or black women to report fecal incontinence in our study, other studies found no such difference in community-dwelling adults.15,17
Further research is needed to better characterize racial and ethnic variations in pelvic floor disorders and to understand why such differences exist. In addition, although the sample sizes were adequate to describe prevalence rates by demographic characteristics, they were too small to provide meaningful estimates of adjusted risk factors, including the effect of delivery type on pelvic floor disorders. Additional years of data will allow for these analyses.
In conclusion, pelvic floor disorders affect a substantial proportion of women and increase with age. Indeed, in a health maintenance organization, older women generated 10 times the number of consults per 1000 women-years for treatment of pelvic floor disorders than did younger women.42
Given the burden pelvic floor disorders place on US women and the health care system, research is needed to further understand their pathophysiology, prevention, and treatment.