Internal Validity in ED Quantification

Posted on June 24th, 2014 by admin

ED Measurement with Canadian viagra pharmacy

Perhaps the single most important factor in ED outcomes study is the ED measurement tool utilized. Quantitative comparison of ED outcomes is severely undermined by the number of established and newly developing (sometimes self-invented) ED measurement tools available to researchers of which not all are specifically defined to address ED. An optimal measurement tool is one that has literature-documented validity and reliability. The use of nonvalidated instruments has been repeatedly shown to overestimate EF.

The Sexual Health Inventory for Men (SHIM) is a five item subscale within the International Index of Erectile Function (IIEF) (its domains include erectile function, orgasmic function, sexual desire, intercourse satisfaction and over-all sexual satisfaction) pertaining to ED and was developed to determine the severity and presence of erectile dysfunction. The five items focus on erections (4 items) and intercourse satisfaction (1 item) and are measured on a 5-point Likert scale ranging from very low to very high. Beside its excellent sensitivity, specificity, reliability, and validity, the SHIM can differentiate among the levels of severity of erectile dysfunction using specified cutoffs (surprisingly under-utilized in the literature and sometimes researchers specify their own cutoffs): no ED (³22), mild (17–21), moderate (8–16), and severe ED (£7). One shortcoming of the SHIM is that it asks about a time period of “over the last 6 months.” Alternatively, the IIEF-6 and the entire IIEF, in general, use a time period of over the last 4 weeks. This time period is more appropriate when assessing erectile function more often (every 3 months) which is common when assessing ED in the immediate post treatment period.

The IIEF-6 and SHIM thus have only minor differences, both yielding robust, reliable data with a high predictive correlation.

When assessing change in ED status after CAP treatment, outcomes can be reported as shifting between ED severities, not as a dichotomous (yes/no) ED variable. A common dichotomous question for ED studies is the ability to achieve penetrative intercourse. There is intrinsic appeal in single item ED assessment tools for convenience, and may be collected in addition to IIEF-related information, but these have proven inferior in quantifying ED. The SHIM has been utilized in over 50 research studies examining prevalence, treatment efficacy, as inclusion criteria, and/or correlation studies since it was initially validated in 1999. Not surprisingly, many authors, as well as the American Brachytherapy Society and the American Urological Association recommend the use of the validated and reliable SHIM or IIEF-5 for the evaluation of erectile dysfunction.

Posted in Erectile Dysfunction | Leave a comment

Comments are closed