Pelvic floor disorders (PFDs) encompass a variety of symptoms and anatomical changes related to the genitourinary tract. Pelvic organ prolapse (POP), urinary incontinence (UI), and anal incontinence (AI) are the most common PFDs encountered in women. These disorders have a tremendous impact on a woman's quality of life and function, and are associated with considerable healthcare costs. In this chapter, the epidemiology of PFDs will be discussed, focusing on three main topics: (1) prevalence and incidence; (2) nonmodifiable demographic risk factors, including age and race; and (3) economic impact.
Prevalence is defined as the total number of cases in a given population at a specific time divided by the number of individuals at risk for disease in the same population. Incidence, or incidence proportion, is defined as the number of new cases of disease that develop in a given population over a period of time divided by the total number of individuals followed for that same time period. The key distinction between these two epidemiologic concepts is that prevalence refers to all cases of disease while incidence refers to new cases of disease.
Defining Pelvic Floor Disorders
Although the concepts of prevalence and incidence may seem straightforward, rates vary widely based on the disease definition and study population. A major issue with determining the prevalence and incidence of PFDs is that each of these conditions is defined in a variety of ways—for example, POP can be diagnosed based on a physical examination or based on a questionnaire that addresses bothersome symptoms. Similarly, the prevalence of UI may be quite different when it is defined as the occurrence of involuntary leakage of urine in the last year versus the last month. The specific population studied can also impact prevalence and incidence. For example, the prevalence of AI will be different in a study of all adult community-dwelling women versus nursing home residents. In order to make meaningful determinations of prevalence and incidence, it is imperative to understand the disease definition and the population studied. This chapter will exclusively discuss the rates of PFDs in women in the United States.
Methods for measuring UI and overactive bladder (OAB) include the frequency of voids, frequency of incontinence episodes, volume of leakage, degree of bother, pad weight, urodynamic findings, clinically demonstrated leakage, or impact on quality of life. Similarly, for AI, the frequency of incontinence, type of stool and/or flatus lost, degree of bother, and impact on quality of life can also be used. Defining POP is equally varied, as it can be measured by symptoms, including frequency, duration, severity or degree of bother, as well as physical examination. Currently, the majority of research studies on POP rely ...