Obstetrics & Gynecology:
Forecasting the Prevalence of Pelvic Floor Disorders in U.S. Women: 2010 to 2050
Wu, Jennifer M. MD, MPH; Hundley, Andrew F. MD; Fulton, Rebekah G. BS; Myers, Evan R. MD, MPH
From the Department of Obstetrics and Gynecology, Duke University, Durham, North Carolina; and the Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio.
Presented at the 30th annual meeting of the American Urogynecologic Society, September 24-26, 2009, Hollywood, Florida.
Corresponding author: Jennifer M. Wu, MD, MPH, Duke University Medical Center, Box 3192, 236 Baker House, Trent Drive, Durham, NC 27710; e-mail: email@example.com.
Financial Disclosure Dr. Wu has received a research grant (#GA90001Y5) from Pfizer, Inc. (New York, NY) for a research project involving assessing the quality of life associated with overactive bladder. The other authors did not report any potential conflicts of interest.
OBJECTIVES: To estimate the number of women who will have symptomatic pelvic floor disorders in the United States from 2010 to 2050.
METHODS: We used population projections from the U.S. Census Bureau from 2010 to 2050 and published age-specific prevalence estimates for bothersome, symptomatic pelvic floor disorders (urinary incontinence [UI], fecal incontinence, and pelvic organ prolapse [POP]) from the 2005 National Health and Nutrition Examination Survey. We abstracted data regarding the number of women aged 20 years or older in 20-year age groups. We assumed that the age-specific prevalences for these disorders and the population distribution of risk factors remained unchanged thru 2050. We also conducted sensitivity analyses that varied both the prevalence estimates and the population projections.
RESULTS: 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 UI will increase 55% from 18.3 million to 28.4 million. For fecal incontinence, the number of affected women will increase 59% from 10.6 to 16.8 million, and the number of women with POP will increase 46% from 3.3 to 4.9 million. The highest projections for 2050 estimate that 58.2 million women will have at least one pelvic floor disorder, with 41.3 million with UI, 25.3 million with fecal incontinence, and 9.2 million with POP.
CONCLUSION: The prevalence of pelvic floor disorders will increase substantially given the changing demographics in the United States. This increase has important implications for public health and the field of gynecology.
LEVEL OF EVIDENCE: III
Pelvic floor disorders, including urinary incontinence (UI), fecal incontinence, and pelvic organ prolapse (POP), represent a major public health issue in the United States.1 Women with these disorders suffer physical and emotional distress, and the economic effect of these disorders on the health care system is substantial.2,3 Recent data from the 2005-2006 National Health and Nutrition Examination Survey (NHANES) found that approximately 24% of adult women have symptoms of at least one pelvic floor disorder.4 This proportion increased with age: 39% of women aged 60 to 79 years and 50% of women aged 80 years or older suffered from at least one disorder.
Several studies have shown that the prevalence of pelvic floor disorders increases with age.5–8 Age is an important risk factor to consider, especially given the changing demographics in the United States. In 2008, there were 38.6 million Americans aged 65 years and older, and our elderly population will more than double to 88.5 million by 2050.9 Similarly, the 85-and-older segment of the population will triple from 5.4 million to 19 million between 2008 and 2050. In addition, among those 65 years and older, women greatly outnumber men. In 2000, there were 6.2 million more elderly women compared with elderly men.10 This disparity increases with age: the percentage of women increases from 54% among those aged 65-69 years to 69% of 85-89 year olds and 80% of 95-99 year olds.10
Recognizing that the U.S. population is aging and that there is a higher percentage of elderly women compared with elderly men, pelvic floor disorders will affect a substantial and increasing proportion of women over the next several decades. Although many observers casually make this claim, we do not have data on the actual number of women who will be affected. These estimates will provide invaluable information on the future demand for care, which correlates to the future need for trained providers to care for these women. Furthermore, this information is vital to policy makers because these projections will reflect the future public health burden of pelvic floor disorders and underscore the importance of research funding to study the etiology, prevention, and treatment of these conditions. For these reasons, the objective of this study was to estimate the future prevalence of pelvic floor disorders using the U.S. Census Bureau population projections from 2010 to 2050.11
MATERIALS AND METHODS
To derive projections for the number of American women with bothersome pelvic floor disorders, we used the prevalence rate estimates from the Pelvic Floor Disorders Network (PFDN) NHANES publication4 and applied these estimates to the U.S. Census Bureau population projections. The National Health and Nutrition Examination Survey is a cross-sectional, national health survey by the National Centers for Health Statistics at the Centers for Disease Control and Prevention, which surveys a representative sample of civilian, noninstitutionalized individuals using a complex, stratified cluster design.12 We used these prevalence data because they are the only published national estimates for all three major pelvic disorders.
For the 2005-2006 cohort of NHANES, 1,961 nonpregnant women aged 20 years or older were included in the PFDN analysis.4 In this study, UI was defined as moderate to severe incontinence based on the two-item, validated Sandvik severity index, which correlates well with incontinence frequency on bladder diaries and incontinence amount on pad weights. This severity index is based on frequency (less than once per month, a few times a month, a few times a week, or every day and/or night) and the amount of leakage (drops, small splashes, or more). Each item has a numeric value, and the value for frequency (1-4) is multiplied by the value for amount (1-3), resulting in an index value of 1 to 12. A score of at least 3 indicates moderate to severe incontinence.13 Fecal incontinence was defined as at least monthly leakage of solid, liquid, or mucous stool using a fecal-incontinence severity index, which accounts for type and frequency. Flatal incontinence was not included in the definition because it is not as bothersome.4 Pelvic organ prolapse was defined as a positive response to the question, “Do you experience bulging or something falling out you can see or feel in the vaginal area?” In the PFDN study, nonpregnant women aged 20 years or older were included. The prevalence rates for each pelvic floor disorder were reported by age using four 20-year age groups (20-39, 40-59, 60-79, and 80 or older).
The U.S. Census Bureau population projections were used to determine the projections for pelvic floor disorders.11 The population projections through 2050 are based on a set of assumptions regarding fertility, mortality, and net immigration.14 For each year, projections are available by age, sex, and race/ethnicity. Population projections based on the middle series are based on middle estimates for all three parameters: fertility rate, life expectancy, and net immigration.15 The middle series predicts that the total population will grow from 310.2 million in 2010 to 439.0 million in 2050. Projections based on the lowest series assume the lowest estimates for fertility rate, life expectancy, and net immigration and suggests a total population of 291.4 million in 2010 to 313.5 million in 2050.16 In contrast, the highest series assumes the highest estimates for all three parameters and predicts the population will grow from 310.9 million in 2010 to 552.8 million in 2050.
This study was exempt from institutional review board review because only publicly available data were analyzed.
For the primary set of projections for pelvic floor disorders, we multiplied the U.S. Census Bureau’s sex- and age-specific population projections by prevalence rates for each pelvic floor disorder by age subgroups (20-39, 40-59, 60-79, and 80 or older). We also calculated the projections for the number of adult women who will have at least one pelvic floor disorder. For the primary outcome, which we will refer to as the “base-case” results, we used the baseline prevalence rates and the middle series of population projections from the U.S. Census Bureau.
Because we cannot be absolutely certain how prevalence rates or population numbers may change over the next 40 years, we conducted two sets of sensitivity analyses. For the first set of sensitivity analyses, we used the low 95% confidence interval estimates from the PFDN NHANES study and then multiplied these prevalence rates with the lowest series of population projections. We will refer to these results as the “best-case scenario” because these results reflect the lowest number of women who will be affected in the future. For the second set of sensitivity analyses, we used the high 95% confidence interval estimates and the highest series of population projections. We will refer to these results as the “worst-case scenario” because these estimates represent the highest number of women who may develop pelvic floor disorders over the next several decades.
The number of American women with pelvic floor disorders will increase substantially from 2010 to 2050 (Table 1). The number of women with UI will increase 55% from 18.3 million in 2010 to 28.4 million in 2050 (Fig. 1). For fecal incontinence, the number of affected women will increase by 59% from 10.6 to 16.8 million (Fig. 2); the number of women with POP will increase 46% from 3.3 to 4.9 million from 2010 to 2050 (Fig. 3). The number of women with at least one pelvic floor disorder will increase from 28.1 million to 43.8 million (Fig. 4). The overall prevalence rates increase each decade given the growing elderly population and the higher prevalence of these conditions in older women (Table 1).
The best- and worst-case scenarios for each pelvic floor disorder and for one or more pelvic floor disorders are presented as the low and high estimates in the ranges in Table 1 and by the bars in Figures 1–4. Even with the best-case scenario, which assumes the lowest prevalence estimate with the lowest series of population projections, there is an increase in the number of women with each pelvic floor disorder over the next 40 years (Table 1). Even with this best-case scenario, 29.3 million women will suffer from at least one pelvic floor disorder by 2050.
The worst-case scenario, based on the highest prevalence estimate with the highest series of population projections, shows a substantial increase for each pelvic floor disorder (Table 1). These results indicate that, by 2050, 41.3 million women will have UI, 25.3 million will develop fecal incontinence, and 9.2 million will have POP. Overall, 58.2 million women will have at least one pelvic floor disorder. For perspective, in 2050, the total female population aged 20 years or older will be 167.8 million; thus, one third of the female population will suffer from at least one pelvic floor disorder given this worst-case scenario.
The U.S. population is aging, and by 2050 the elderly population, those 65 years and older, will more than double from 38.7 million in 2008 to 88.5 million. As our population ages, medical conditions such as pelvic floor dysfunction will become increasingly burdensome in terms of reduced quality of life, workforce productivity, and cost to both the individual and the health care system as a whole. Recently, Nygaard et al17 presented the national, population-based prevalence estimates of urinary and fecal incontinence and POP generated from a single collection of source data using NHANES data from 2005-2006. These data were applied to the U.S. Census Bureau’s population projections to quantify the future potential effect of these disorders. Given these data, the disease burden of pelvic floor disorders will increase substantially, and, by 2050, 43.8 million women will suffer from at least one pelvic floor disorder. Because it is possible for prevalence rates and population projections to vary over the coming decades, we also calculated best-case and worst-case scenarios. Even with the best-case scenario, 29.3 million women will have at least one pelvic floor disorder by 2050; in the worst-case scenario, this estimate could be as high as 58.1 million, which represents one third of the projected total adult female population in 2050.
The magnitude of these projections has important implications for both individuals and society. In 2008, the National Institutes of Health highlighted the public-health effect of pelvic floor disorders with a State of the Science conference on the prevention of fecal and urinary incontinence in adults. The final conference statement outlined the burden of incontinence on individuals and their caretakers and the associated economic costs.18 Those with UI and fecal incontinence are embarrassed and feel shame, and their lives are disrupted by these accidents. Women with prolapse similarly suffer from pelvic discomfort as well as bladder and bowel dysfunction, and the reduced quality of life secondary to these pelvic floor disorders has been well-documented.19,20 In addition to affecting individuals, incontinence requires additional amounts of both informal (unpaid assistance from family members or friends) and formal (paid assistance) caregiving.18 Ultimately, the costs of incontinence, which includes supplies, treatment, caregiving, and the complications from incontinence, are significant. Estimates for the cost of UI alone totaled $20 billion in 2000,3 which does not account for direct and indirect costs resulting from fecal incontinence and prolapse.
Given our projections, the number of women seeking treatment for their pelvic floor disorder also will increase substantially. Our findings reflect those of Luber et al,21 which applied data regarding the number of consultations for pelvic floor disorders in the Kaiser Southern California system to population projections in 2000 compared with 2030. They concluded that the number of national consultations in 2000 was 618,165 and that this would increase to 954,397 in 2030, an increase of 45% during a time period when the population is projected to expand only 22%. In terms of treatment, women have the option of behavioral therapy, other nonsurgical options, or surgery. Currently, the lifetime risk of undergoing a single operation for incontinence or prolapse by age 80 is 11.1%.22 Estimates show that, annually in the United States, approximately 80,000, 220,000,23 and 3,50024 surgeries are performed for UI, POP, and fecal incontinence, respectively; these figures likely will increase given the projected numbers of women with these disorders in the coming decades. Unfortunately, these surgeries are associated with morbidity, especially in the elderly. Sung et al reports a higher mortality risk with each successive decade when comparing women older than 60 years with those younger than 60.25 In addition, recurrence of disease is common, with almost 30% of women requiring a repeat procedure.22 Given the effect on quality of life, the economic costs, and the implications of treatment for these women, pelvic floor disorders will become an even greater public health issue over the next 40 years.
The strengths of this study include that we used the best available data. We incorporated prevalence rates from national estimates based on NHANES and the U.S. Census Bureau projections. We also employed methodology similar to previous population projection analyses.26,27 Furthermore, to account for uncertainties in the prevalence rates as well as the population projections from the U.S. Census Bureau, we conducted sensitivity analyses that varied both of these. Thus, we were able to present both the best-case and the worst-case scenarios, which are illustrated by the range bars in Figures 1–4.
As with other population-projection studies, there are limitations to our analysis. First, the prevalence rates for each pelvic floor disorder were assumed to remain constant over the course of the next four decades. It is possible that changes in risk factors, such as obesity, smoking, and vaginal deliveries, could affect prevalence rates. In addition, changes in the racial and ethnic composition of our population could affect prevalence. For example, the Hispanic population is projected to triple from 47 million to 133 million from 2008 to 2050.9 However, at this time, we have very limited data regarding racial- or ethnic-specific prevalence rates. Because prevalence may not be that stable, low and high 95% confidence-interval estimates were used in sensitivity analyses to understand how changes in prevalence would affect the projections. Regardless of whether there is an over- or underestimation of actual prevalence rates in the future, the overall trend clearly demonstrates an increasing number of women who will be affected by pelvic floor dysfunction.
Finally, we must realize that these data should be seen as a call to action. Studies such as this merely elucidate the presence of a problematic trend—in this case the expectation that a rapidly growing segment of our population will struggle with urinary incontinence, fecal incontinence, and POP in the coming years. Based on these estimates, nearly 44 million women will suffer from at least one pelvic floor disorder by 2050. The direct and indirect costs of these issues to society and the effect on women’s quality of life are well-documented. We also need to ensure that there are enough providers who are specifically trained to care for these women. Furthermore, these findings also should help to prioritize research that explores the etiologies of these disorders, thereby aiding in the identification of high-risk groups. The ability to identify women at high risk would be valuable in determining which women may want to avoid particular risk factors and which women would benefit most from preventive interventions and specific treatment recommendations. The magnitude of women who will be affected by pelvic floor disorders also underscores the importance of developing effective prevention and treatment strategies through the support of research funding. Advances in both prevention and treatment of pelvic floor disorders will help to reduce the estimated public health burden of these diseases on our society in the future.
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© 2009 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.
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