Vulvodynia is not created equally: empirical classification of women with vulvodynia

Abstract

Background

Vulvodynia classification is based on the sensory dimensions of pain and does not include psychological factors associated with the pain experience and treatment outcomes. Previous work has shown that individuals with chronic pain can be classified into subgroups based on pain sensitivity, psychological distress, mood, and symptom severity.

Objective

The aim of this study was to identify distinct subgroups of women with vulvodynia enrolled in the National Vulvodynia Registry. We hypothesized that women with vulvodynia can be clustered into subgroups based on distress and pain sensitivity.

Design

A cross-sectional study.

Methods

We conducted an exploratory hierarchical agglomerative cluster analysis using Ward’s cluster method and squared Euclidean distances to identify unique subgroups based on baseline psychological distress and pain sensitivity. The variables included the catastrophizing subscale of the Coping Strategies Questionnaire, the Beck Depression Inventory, the State Trait Anxiety Index-Trait scale, McGill Pain Questionnaire-Affective subscale, and vulvar and pelvic muscle pressure pain sensitivity.

Subjects

Eight sites enrolled women who presented with vaginal or vulval pain of at least 3-month duration.

Results

Two distinct subgroups, high pain sensitivity with high distress (n=27) and low pain sensitivity with low distress (n=100), emerged from the cluster analysis. Validation indicated that subgroups differed in terms of clinical pain intensity, sensory aspects of pain, and intercourse pain.

Conclusion

Empirical classification indicates that unique subgroups exist in women with vulvodynia. Providers should be aware of the heterogeneity of this condition with respect to pain-related distress and pain sensitivity.

Keywords:

• vulvodynia
• chronic vulvar pain
• pelvic pain
• National Vulvodynia Registry
• classification
• patient subgroups

Acknowledgments

This research was supported by funding from the National Vulvodynia Association and the Patty Brisben Foundation for Women’s Sexual Health and Florida Hospital (Orlando, FL, USA). Methodology developed for the NVR was developed with the help of Dr. Denniz Zolnoun with funding from the National Institutes of Health, K23 HD053631-01: Refining Diagnosis Criteria of Pain Disorder: Vulvar Vestibulitis Syndrome. Dr. Alappattu is supported by the Rehabilitation Research Career Development Program (National Center for Medical and Rehabilitation Research and National Institute for Neurological Disorders and Stroke K12 HD055929).

Disclosure

Dr Jessica Feranec serves on the speaker’s bureau for Exparel® (bupivacaine liposome injectable suspension) produced by Pacira Pharmaceutical Inc. Dr Lamvu serves on the Advisory Board for Daiichi Sankyo Pharmaceuticals and has research funding from Pfizer Grants for Learning and Change. The other authors report no conflicts of interest in this work.