International Index of Erectile Function (IIEF)

Abstract

The International Index of Erectile Function (IIEF) is the definitive, multidimensional self-report scale designed for the comprehensive assessment of male sexual function. Introduced in 1997, the IIEF is globally recognized as the gold standard clinical and research instrument for diagnosing and quantifying the severity of Erectile Dysfunction (ED). The full 15-item version provides quantitative scores across five core domains critical to sexual health: Erectile Function, Orgasmic Function, Sexual Desire, Intercourse Satisfaction, and Overall Satisfaction. Its widespread adoption ensures reliable evaluation of treatment efficacy across various clinical and pharmacological studies.

Keywords

Erectile Dysfunction, IIEF, Sexual function, Quality of life, Urology, Psychometrics, Male sexual health, Intercourse satisfaction, Orgasmic function, Clinical trials, Libido.

Authors

Rosen, R. C., Riley, A., Wagner, G., Osterloh, I. H., Kirkpatrick, J., Mishra, A.

Purpose

The primary purpose of the International Index of Erectile Function (IIEF) is to establish a standardized and validated metric for the clinical assessment of male sexual capability, with a specific focus on identifying the presence and severity of Erectile Dysfunction. Clinically, the IIEF is indispensable for initial diagnosis, guiding appropriate treatment selection (whether pharmacological, surgical, or psychological), and rigorously monitoring patient response to these interventions over time. Its structured scoring system allows clinicians to move beyond subjective reporting to objective quantification of functional improvement.

Beyond its clinical utility, the IIEF is extensively employed in large-scale pharmaceutical and academic clinical trials investigating novel treatments for ED. Its multidimensional design allows researchers to capture granular data on specific facets of sexual health, providing a comprehensive view of changes in function rather than relying solely on a binary measure of treatment success or failure. The scale’s robust psychometric properties ensure that data collected across different studies and populations are reliable and comparable.

Construct

The IIEF is designed to measure the complex construct of male sexual function, which is conceptualized not as a monolithic entity but as a multidimensional phenomenon encompassing both physiological readiness and psychological satisfaction. This approach ensures that the assessment captures the holistic experience of sexual activity, moving beyond simple physical capacity to include emotional and relational components essential for overall sexual health.

The scale systematically assesses five distinct domains, each reflecting a critical component of satisfactory sexual activity:

• Erectile Function (EF): This domain measures the critical ability to achieve and maintain an erection adequate for satisfactory sexual intercourse. It is frequently utilized as the primary outcome measure in treatment studies.
• Orgasmic Function (OF): This assesses the frequency of ejaculation and the subjective quality or feeling of orgasm experienced by the respondent.
• Sexual Desire (SD): This reflects the respondent’s libido, measuring the frequency and intensity of sexual desire experienced over the recall period.
• Intercourse Satisfaction (IS): This evaluates the degree of personal satisfaction derived specifically from sexual intercourse, considering factors like frequency of attempts and overall personal enjoyment.
• Overall Satisfaction (OS): This captures the patient’s general satisfaction with their total sex life and the quality of their sexual relationship with a partner.

Validity

The International Index of Erectile Function exhibits high levels of construct, content, and criterion validity, firmly establishing its status as a definitive and trustworthy measure of male sexual health. Construct validity is substantiated by the scale’s consistent and robust factor structure, which reliably confirms the existence of the five hypothesized domains across numerous diverse populations and languages worldwide. This structural integrity ensures the scale measures what it intends to measure.

Furthermore, strong Criterion validity supports the IIEF’s diagnostic utility. Scores derived from the scale correlate highly with clinical diagnoses of ED severity as determined by experienced physicians. Crucially, the IIEF demonstrates high sensitivity to change, effectively tracking improvements or deterioration following effective treatments, such as the administration of phosphodiesterase type 5 inhibitors. This sensitivity allows the scale to successfully differentiate between men suffering from varying degrees of ED and healthy controls.

Reliability

The reliability of the IIEF is considered excellent, a finding supported by rigorous psychometric evaluation across its history. High internal consistency has been consistently reported across all five domains. Measurements, typically reported via Cronbach’s coefficient alpha, generally exceed the acceptable threshold of 0.70, often reaching very high scores, particularly within the six-item Erectile Function domain.

The scale also demonstrates strong Test-retest reliability. This characteristic indicates that the IIEF yields stable and consistent scores when administered repeatedly to patients whose underlying clinical condition has not genuinely changed. This stability is paramount for the IIEF’s application in longitudinal studies and for the precise monitoring of chronic conditions, ensuring that any fluctuations in scores reflect true clinical progression rather than inherent measurement error.

Factor Analysis

The seminal paper detailing the development of the IIEF, published by Rosen et al. in 1997, employed both exploratory and confirmatory factor analysis techniques. This statistical process was crucial for establishing and verifying the hypothesized multidimensional structure of the instrument, confirming that male sexual function is underpinned by five distinct, albeit interrelated, factors.

The factor structure guides the scoring methodology of the 15-item scale. The items are grouped into their respective domains, and scores are summed to produce subscale totals. The defined item loadings and corresponding score ranges are:

• Erectile Function: items 1, 2, 3, 4, 5, 15 (Total score range: 6–30)
• Orgasmic Function: items 9, 10 (Total score range: 2–10)
• Sexual Desire: items 11, 12 (Total score range: 2–10)
• Intercourse Satisfaction: items 6, 7, 8 (Total score range: 3–15)
• Overall Satisfaction: items 13, 14 (Total score range: 2–10)

Instrument

Test Type: Self-report questionnaire, Multidimensional scale

Format: The scale consists of 15 items, primarily utilizing 6-point Likert-type scales. Respondents are asked to reflect on their experiences over a 4-week recall period. Scores are mathematically summed within each specific subdomain.

Language Available: The IIEF has been extensively translated and validated for use in numerous major global languages, including Spanish, German, Chinese, Japanese, and French, ensuring its utility in diverse international research settings.

Population Group: Adult males requiring a standardized assessment of their sexual function, particularly those presenting with symptoms related to erectile difficulties.

Age Group: Typically utilized with adult men, defined as 18 years of age and older.

Population Details: While initially validated on clinical populations diagnosed with or suspected of having Erectile Dysfunction, the scale is also frequently used in general population surveys to establish normative data for male sexual health.

Test Methodology: The IIEF is patient-administered, suitable for either pencil-and-paper completion or electronic survey formats. Scoring involves summing item scores per domain. The resulting score for the Erectile Function domain is often used independently to classify the severity of ED:

• 26-30: No Erectile Dysfunction (ED)
• 22-25: Mild ED
• 17-21: Mild-to-Moderate ED
• 11-16: Moderate ED
• 5-10: Severe ED

Keywords

Erectile Function, Libido, Sexual satisfaction, Psychometrics, Clinical trial outcome measure, Urological assessment, Self-report instrument.

Authors

Author ORCID Identifier: N/A (Information not provided in source.)

Affiliation Email addresses: N/A (Information not provided in source.)

Correspondence Address: N/A (Information not provided in source.)

Permissions & Fee and Test Year

The International Index of Erectile Function (IIEF) was first published in 1997. Given its proprietary nature and frequent use in commercial pharmaceutical research, formal permissions or licensing agreements may be required for its use. Copyright holders, often associated with Pfizer or the original research group, typically regulate usage. Fees may apply, particularly for large-scale commercial or non-academic applications of the instrument.

Reference’s

Rosen, R. C., Riley, A., Wagner, G., Osterloh, I. H., Kirkpatrick, J., & Mishra, A. (1997). The international index of erectile function (IIEF): A multidimensional scale for assessment of erectile dysfunction. Urology, 49, 822-830.

The instrument can be accessed online at several locations, including:

• http://www.seekwellness.com/mens_sexuality/questionnaire.htm
• https://www.researchgate.net/file.PostFileLoader.html?id=55926ccd6225ff5de48b4682&assetKey=AS%3A273804520034308%401442291492243

The original PDF referenced in the source content can be downloaded here: http://dro.deakin.edu.au/eserv/DU:30067449/stefanou-theassociations-2014A.pdf

Items of the International Index of Erectile Function (IIEF)

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

1. Over the past 4 weeks‚ how often were you able to get an erection during sexual activity?

• No sexual activity
• Almost always or always
• Most times (much more than half the time)
• Sometimes (about half the time)
• A few times (much less than half the time)
• Almost never or never

2. Over the past 4 weeks‚ when you had erections with sexual stimulation‚ how often were your erections hard enough for penetration?

• No sexual stimulation
• Almost always or always
• Most times (much more than half the time)
• Sometimes (about half the time)
• A few times (much less than half the time)
• Almost never or never

Questions 3‚ 4 and 5 will ask about erections you may have had during sexual intercourse.

3. Over the past 4 weeks‚ when you attempted sexual intercourse‚ how often were you able to penetrate (enter) your partner?

• Did not attempt intercourse
• Almost always or always
• Most times (much more than half the time)
• Sometimes (about half the time)
• A few times (much less than half the time)
• Almost never or never

4. Over the past 4 weeks‚ during sexual intercourse‚ how often were you able to maintain your erection after you had penetrated (entered) your partner?

• Did not attempt intercourse
• Almost always or always
• Most times (much more than half the time)
• Sometimes (about half the time)
• A few times (much less than half the time)
• Almost never or never

5. Over the past 4 weeks‚ during sexual intercourse‚ how difficult was it to maintain your erection to completion of intercourse?

• Did not attempt intercourse
• Almost always or always
• Most times (much more than half the time)
• Sometimes (about half the time) 0 A few times (much less than half the time)
• Almost never or never

6. Over the past 4 weeks‚ how many times have you attempted sexual intercourse?

• No attempts
• 1-2 attempts
• 3-4 attempts
• 5-6 attempts
• 7-10 attempts
• 11 or more attempts

7. Over the past 4 weeks‚ when you attempted sexual intercourse how often was it satisfactory for you?

• Did not attempt intercourse
• Almost always or always
• Most times (much more than half the time)
• Sometimes (about half the time)
• A few times (much less than half the time)
• Almost never or never

8. Over the past 4 weeks‚ how much have you enjoyed sexual intercourse?

• No intercourse
• Very highly enjoyable
• Highly enjoyable
• Fairly enjoyable
• Not very enjoyable
• Not enjoyable

9. Over the past 4 weeks‚ when you had sexual stimulation or intercourse how often did you ejaculate?

• Did not attempt intercourse
• Almost always or always
• Most times (more than half the time)
• Sometimes (about half the time)
• A few times (much less than half the time)
• Almost never or never

10. Over the past 4 weeks‚ when you had sexual stimulation or intercourse how often did you have the feeling of orgasm or climax (with or without ejaculation)?

• No sexual stimulation or intercourse
• Almost always or always
• Most times (much more than half the time)
• Sometimes (about half the time)
• A few times (much less than half the time)
• Almost never or never

Questions 11 and 12 ask about sexual desire. Let’s define sexual desire as a feeling that may include wanting to have a sexual experience (for example‚ masturbation or intercourse)‚ thinking about ha‎ving sex or feeling frustrated due to a lack of sex.

11. Over the past 4 weeks‚ how often have you felt sexual desire?

• Almost always or always
• Most times (much more than half the time)
• Sometimes (about half the time)
• A few times (much less than half the time)
• Almost never or never

12. Over the past 4 weeks‚ how would you rate your level of sexual desire?

• Very high
• High
• Moderate
• Low
• Very low or none at all

13. Over the past 4 weeks‚ how satisfied

• Very satisfied
• Moderately satisfied
• About equally satisfied and dissatisfied
• Very dissatisfied

14. Over the past 4 weeks‚ how satisfied have you been with your sexual relationship with your partner?

• Very satisfied
• Moderately satisfied
• About equally satisfied and dissatisfied
• Moderately dissatisfied
• Very dissatisfied

15. Over the past 4 weeks‚ how do you rate your confidence that you can get and keep your erection?

• Very high
• High
• Moderate
• Low
• Very low