Epidemiology can be divided into two distinct categories—descriptive and analytic. Descriptive epidemiology gives prevalence and incidence data that allow an understanding of individuals who sustain or have sustained a disorder, the characteristics of the population, the age and other population characteristic differences in rates of the disorder, and the number of new cases within a given time. The physician can determine how many people have the disorder in any given population and the age and status category that affect the condition. Public health efforts can be directed toward problem solving and marketing populations defined for products or treatment modalities. Incidence data also help identify populations that are at a greater risk for the problem. Analytic epidemiology, which involves an analysis of risk factors for the disorder, provides data for developing preventive medicine strategies.

The occurrence rate of erectile dysfunction is expressed in two different ways—prevalence and incidence. Prevalence describes the number of people who have the disorder at a given time and can be characterized further as current or lifetime. Usually, the duration is expressed as the number of patients affected per year. Incidence refers to the number of new cases of a disorder occurring in a specific population during a discrete period of time. Incidence data necessarily come from longitudinal studies as opposed to cross-sectional studies and help sort out confounding effects of or on the disorder. In the published literature, many more articles describe the prevalence versus the incidence of erectile dysfunction.

Incidence and prevalence data can come from two different types of populations. The first population represents persons seen for the disorder in a hospital, clinic, or office. These patients may have another specific disorder or disease, such as diabetes mellitus, and are found to have the disorder to be studied, or they may be part of a general patient group that the particular physician or clinic sees. Reports from these types of populations offer the opportunity to collect and publish data from carefully monitored physiologic and biologic tests, physical examinations, and case histories, offering a window for understanding complex etiologies and courses of a particular dysfunction. Until recently, these types of reports were the more commonly published in the peer-reviewed scientific literature; however, such studies offer little insight into the problem as it affects the population at large.

The other population source includes persons in community-based samples who are screened for the disorder by questionnaires or other methods such as direct interviews. Boyle<sup>3 Boyle P. Epidemiology of erectile dysfunction. Textbook of Erectile Dysfunction Oxford: Ibis Medical Media (1999).  15

Cliquez ici pour aller à la section Références</sup> cautions that the data obtained from self-reports should be suspect, especially for disorders associated with social stigmatism. Some members of the population studied may not consider a disorder to be a problem for them even though they, in fact, sustain it. Erectile dysfunction can be such a disorder. Community studies define the potential number of patients sustaining the disorder who might benefit from treatment. To be valid, the community sample should be representative of the population studied, with social, cultural, and health status data available. Although there are numerous population studies in the literature, few have used contemporary probability-based sampling strategies, including a key study by Kinsey published in the late 1940s.<sup>9 Gebhard P.H., Johnson A.B. The Kinsey Data: Marginal Tabulations of the 1938–1963 Interviews Conducted by the Institute for Sex Research Philadelphia: WB Saunders (1979).  125

Cliquez ici pour aller à la section Références, 13 Kinsey A.C., Pomeroy W.B., Martin C.E.   Sexual Behavior in the Human Male Philadelphia: WB Saunders (1948). 

Cliquez ici pour aller à la section Références</sup> The more recent studies are discussed in this article to define the incidence and prevalence of erectile dysfunction. The reader is referred to more extensive reviews of epidemiologic data from all sources.<sup>3 Boyle P. Epidemiology of erectile dysfunction. Textbook of Erectile Dysfunction Oxford: Ibis Medical Media (1999).  15

Cliquez ici pour aller à la section Références, 17 Lewis R.W., McKinlay J., Laumann E. , et al. Epidemiology and natural history of erectile dysfunction: Risk factors including iatrogenic and aging. Proceedings of First International Consultation on Erectile Dysfunction Plymouth, UK: Health Publication (1998).  1-33

Cliquez ici pour aller à la section Références, 27 Spector I.P., Carey M.P. Incidence and prevalence of the sexual dysfunctions: A critical review of the empirical literature Arch Sex Behav 1990 ;  19 : 389  [cross-ref]

Cliquez ici pour aller à la section Références</sup>