Sexual Interest and Desire Inventory—Female

Sexual Interest and Desire Inventory—Female

ANITA H. CLAYTON,1 University of Virginia DAVID GOLDMEIER, St Mary’s Hospital, London ROSSELLA E. NAPPI, University of Pavia, Italy

GLEN WUNDERLICH, Boehringer Ingelheim (Canada), Ltd., Burlington, Ontario

DIANE J. LEWIS-D’AGOSTINO AND ROBERT PYKE, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT

The Sexual Interest and Desire Inventory—Female (SIDI- F) is a clinician-administered instrument to quantitatively assess Hypoactive Sexual Desire Disorder (HSDD) severity in women. It is a 17-page instrument available in its entirety at the companion website for this handbook: www. routledge.com/textbooks/9780415801751.

Description

The SIDI-F is a clinician-rated instrument consisting of 13 items (relationship—sexual, receptivity, initiation, desire— frequency, affection, desire—satisfaction, desire—dis- tress, thoughts—positive, erotica, arousal—frequency, arousal ease, arousal continuation, and orgasm), as well as a 5-item diagnostic module. The items in the diagnostic module are for information purposes on common interfering conditions (e.g., fatigue, depression, and pain) and do not contribute to the total score.

The SIDI-F was developed in a collaborative effort by a group of academic sexual dysfunction researchers, pharmaceutical industry professionals, and clinicians. It originally consisted of 17 items but was modified following preliminary testing and item response analysis (Sills et al., 2005).

The resulting “near-final” version, consisting of a 13-item clinician-rated instrument with 30-day recall, was tested for reliability and validity in a two-center North American pilot validation study conducted on 90 women with HSDD, Female Orgasmic Disorder (FOD), or no Female Sexual Dysfunction (FSD; Clayton et al., 2006). The reliability and validity of the final version of the SIDI-F were subsequently established in two multicenter, nontreatment studies, conducted in North America (n = 223) and Europe (n = 254), in women with HSDD (both studies), Female Sexual Arousal Disorder (FSAD; North American study only), or no FSD (both studies; Lewis-D’Agostino et al., 2007; Nappi et al., 2008).

The SIDI-F is designed to assess HSDD severity in adult women, regardless of age, menopausal status, or country. It was validated for use by clinicians trained in FSD, so its use by untrained clinicians to evaluate patients against a normative sample can only be advisory. However, its ease of use and the low level of interpretation required by the clinician are highly compatible with use by all clinicians to monitor changes in symptoms over time with treatment, especially by clinicians experienced in treating FSD.

Response Mode and Timing

Following a brief introduction, the administering clinician progresses through the 13 items of the instrument with the respondent. Each item (written in bold) consists of one or two questions, which are read verbatim by the clinician. Supplementary information (written in plain typeface) is provided to guide more specific probes. Additional questions are asked until the respondent gives a clear answer to which the clinician can assign a specific severity score. The SIDI-F takes approximately 15 minutes to administer.

Scoring

The SIDI-F uses two kinds of ratings: 8 items are rated in terms of symptom intensity only, whereas 5 items are rated in terms of both symptom intensity and frequency. The 5 dual-rated items are arranged in a grid: symptom intensity increases from left to right and symptom frequency increases from top to bottom. The intersection of these points gives the overall severity rating.

Items are rated from 0 to 3, 4, or 5, depending on the item. The total score ranges from 0 to 51, with higher scores indicating greater levels of sexual interest. A total score of 33 or less indicates the presence of HSDD.

Reliability

For all subjects, the Cronbach’s alpha for the SIDI-F was on both day 0 and day 28 in the North American study (N = 223). In the European study (N = 254), the corresponding values were .93 and .92 on day 0 and day 28, respectively.

Test-retest reliability was assessed using the Pearson correlation and intraclass correlation coefficient (ICC). For all subjects, the Pearson correlation and ICC coefficients for the SIDI-F score between day 0 and day 28 were .86 and .85, respectively, in the North American study, and .90, respectively, in the European study (Lewis- D’Agostino et al., 2007; Nappi et al., 2008).

Validity

For discriminant validity, a two-way analysis of covariance, with age categories and country as fixed effects, was used. In the North American study, the SIDI-F score was significantly lower for women diagnosed with HSDD than those diagnosed with FSAD, or with no FSD, at day 0 (p

< .001, for both; Lewis-D’Agostino et al., 2007). In the European study, the SIDI-F score was significantly lower for women diagnosed with HSDD than those with no FSD at day 0 (p < .001; Nappi et al., 2008). Similar findings were seen for women aged 50 years or under and aged over 50 years in both studies. Further, the SIDI-F score showed discriminant validity regardless of menopausal status (both studies), or country (European study only).

Convergent validity was assessed by comparing responses on the SIDI-F to those on the Female Sexual Function Index (FSFI; Meston, 2003; Rosen et al., 2000) and the Changes in Sexual Functioning Questionnaire—Female (CSFQ- F; Clayton, McGarvey, & Clavet, 1997) using Pearson’s correlation. In both studies, the SIDI-F score was highly correlated (all correlations > .60) with FSFI and CSFQ-F total scores in women with HSDD at day 0 (irrespective of age group), demonstrating convergent validity (Lewis- D’Agostino et al., 2007; Nappi et al., 2008).

Divergent validity was assessed by comparing responses on the SIDI-F with those on the Locke-Wallace Marital Adjustment Scale (MAS; Locke & Wallace, 1959) using Pearson’s correlation. In both studies, the SIDI-F score was not highly correlated (.02 and .23 for the two studies) with the MAS score in women with HSDD at day 0 (irrespective of age group), demonstrating divergent validity (Lewis- D’Agostino et al., 2007; Nappi et al., 2008).

Sensitivity to change was assessed retrospectively in the North American and European studies. At study end, the percentage change from baseline in SIDI-F score was sig- nificantly correlated with percentage change in FSFI total and desire domain scores in both studies (p < .0001, for all). Sensitivity to therapeutically induced change was demon- strated in two proof-of-concept trials of an agent to treat HSDD; SIDI-F score was significantly correlated with the Clinical Global Impression of Improvement score (which assesses overall improvement in sexual functioning with study medication throughout the 12-week treatment period in both studies (p < .0001, for all; data on file, Boehringer Ingelheim).

Other Information

The SIDI-F was copyrighted in 2004 by Drs. Anita Clayton, Sandra Leiblum, Kenneth R. Evans, Terrence Sills, Robert Pyke, Rosemary Basson, and R. Taylor Segraves. Use of this instrument by the scientific community is encouraged and free of charge as long as the abovementioned copy- right notice is reproduced and as long as the instrument is not altered or modified without the express written consent of the copyright holders. Inquiries for such consents may be addressed to Dr. Robert Pyke at Boehringer Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Rd, Ridgefield, CT 06877; [email protected]

Address correspondence to Anita Clayton, University of Virginia Health System, Department of Psychiatric Medicine, 2955 Ivy Road, Northridge Suite 210, Charlottesville, VA 22903; e-mail: [email protected]

References

This measure may be viewed in its entirety at the companion website for this book: http://www.routledge.com/textbooks/9780415801751