Psychometric Evaluation of PROMIS Sexual Function and Satisfaction Measures in a Longitudinal Population-Based Cohort of Men With Localized Prostate Cancer

Abstract

Background: There are multiple treatment options for men with localized prostate cancer that provide similar curative efficacy but differ in their impact on sexual functioning.

Aim: To evaluate the psychometric properties of the Patient-Reported Outcomes Measurement Information System (PROMIS) Sexual Function and Satisfaction (SexFS) measures, including items from versions 1 and 2 of the short forms.

Methods: A population-based cohort of men across North Carolina completed surveys via phone interviews at baseline (prior to treatment) and at 3, 12, and 24 months after cancer treatment initiation. Surveys included the PROMIS SexFS domains of interest in sexual activity, erectile function, orgasm, and satisfaction and the Prostate Cancer Symptom Indices. Analyses included descriptive statistics, assessment of structural validity using confirmatory factor analysis and item response theory, tests for differential item functioning, assessment of convergent validity using correlations, and evaluation of responsiveness of the PROMIS SexFS measures over time. We hypothesized that men undergoing surgery (prostatectomy) would report the poorest sexual function at the 3-month survey.

Results: Sample size varied by assessment point and ranged from 332‒939 men, consisting of 30% non-white men, and 30% of the sample had a high school degree or less. The items within the PROMIS orgasm domain did not form a unidimensional scale. PROMIS measures of interest in sexual activity, erectile function, and satisfaction were unidimensional and highly correlated with related Prostate Cancer Symptom Indices measures (eg, erectile function, r = 0.84‒0.95). Erectile function in the surgery group declined more at 3 months compared to the no-surgery group (2 points); this difference narrowed at 12 and 24 months after surgery, as the surgery group recovered over time. Results were similar for PROMIS Interest in Sexual Activity and PROMIS Satisfaction scales.

Clinical implications: The PROMIS SexFS measures may be used to identify effective interventions to treat sexual dysfunction and monitor sexual functioning in men with prostate cancer over time.

Strength & limitations: This study was limited to men living in North Carolina who could self-report their health-related quality of life in English. However, this study was able to include more men from vulnerable populations by allowing them to self-report over the phone.

Conclusion: This study provided strong support for use of the PROMIS SexFS (version 2) measures in men with localized prostate cancer to assess sexual interest, erectile function, and satisfaction over time. Reeve BB, Wang M, Weinfurt K, et al. Psychometric Evaluation of PROMIS Sexual Function and Satisfaction Measures in a Longitudinal Population-Based Cohort of Men With Localized Prostate Cancer. J Sex Med 2018;15:1792-1810.

Keywords: Erectile Function; Interest in Sexual Activity; Satisfaction With Sex.

Conflict of interest statement

Conflict of interest: The authors declare that they have no conflict of interest.

Copyright © 2018 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1.

Example Path Diagram for a Longitudinal Two-Group IRT Model. θ¯* = latent mean estimate σ*2 = latent variance estimate S∗ = specific factors (fixed to standard normal) that capture item autocorrelations.

Figure 2.

Changes of Factor Means (by Surgery Groups) Over Time for Three PROMIS SexFS Domains. Within each domain, the metric is defined by fixing the no-surgery group at baseline as standard normal. Vertical bars represent 95% confidence intervals for the corresponding mean estimates.