An important factor that can influence ED study outcomes is the seemingly innocuous definition selected for erectile function. Two identical studies, one with EF defined as the ability to achieve and maintain penile erection sufficient for satisfactory sexual performance, the other as partial erections occasionally sufficient for penetrative intercourse could yield very different results. A cohort study of 260 men revealed 5% reported erections firm enough for intercourse, but 61% reported sexual function as good or very good.
Differences could be further exacerbated if the use of erectile aides such as PDE5I is allowed and documented in one study but not in the other. The National Institute of Health (NIH) identified the definition of erectile dysfunction as the “inability to attain and/or maintain a penile erection sufficient for satisfactory sexual performance” and this definition was subsequently accepted by the World Health Organization and the International Consultation on Urologic Disease. The NIH definition provides an excellent overall definition for researchers and clinicians to utilize as a starting point in explicating a precise operational definition of erectile dysfunction according to the particulars of the situation being explored. Many studies in the literature do not explicate a specific definition of erectile dysfunction and those that did vary greatly in the literature. Examples of imprecision in terminology in the ED literature include terms like “sexual concerns,” statements describing “tumescence,” “impotence,” “loss of potency,” “cannot get erections,” and “difficulty with erections.”
Defining erectile dysfunction in terms of the inability to penetrate and/or have intercourse with the erec- tion may better describe the level of functional rigidity for men who are engaged in a sexual relationship involving intercourse. Despite being more precise, definitions with strict functional rigidity criteria may not apply to sexual relationships in which penetrative intercourse is considered less important (such as some homosexual relationships). Today’s erectile function definitions must specify whether PDE5I or other erectile aides are allowed or excluded.