The Persistency Index: a novel screening tool for identifying myofascial pelvic floor dysfunction in patients seeking care for lower urinary tract symptoms

Abstract

Background: Patients with myofascial pelvic floor dysfunction often present with lower urinary tract symptoms, such as urinary frequency, urgency, and bladder pressure. Often confused with other lower urinary tract disorders, this constellation of symptoms, recently termed myofascial urinary frequency syndrome, is distinct from other lower urinary tract symptoms and optimally responds to pelvic floor physical therapy. A detailed pelvic floor myofascial examination performed by a skilled provider is currently the only method to identify myofascial urinary frequency syndrome. Despite a high influence on quality of life, low awareness of this condition combined with no objective diagnostic testing leads to the frequent misdiagnosis or underdiagnosis of myofascial urinary frequency syndrome.

Objective: This study aimed to develop a screening measure to identify patients with myofascial urinary frequency syndrome (bothersome lower urinary tract symptoms secondary to myofascial pelvic floor dysfunction) from patient-reported symptoms.

Study design: A population of patients with isolated myofascial urinary frequency syndrome was identified by provider diagnosis from a tertiary urology practice and verified by standardized pelvic floor myofascial examination and perineal surface pelvic floor electromyography. Least Angle Shrinkage and Selection Operator was used to identify candidate features from the Overactive Bladder Questionnaire, Female Genitourinary Pain Index, and Pelvic Floor Distress Index predictive of myofascial urinary frequency syndrome in a pooled population also containing subjects with overactive bladder (n=42), interstitial cystitis/bladder pain syndrome (n=51), and asymptomatic controls (n=54) (derivation cohort). A simple, summated score of the most discriminatory questions using the original scaling of the Pelvic Floor Distress Index 5 (0-4) and Genitourinary Pain Index 5 (0-5) and modified scaling of Female Genitourinary Pain Index 2b (0-3) had an area under the curve of 0.75. As myofascial urinary frequency syndrome was more prevalent in younger subjects, the inclusion of an age penalty (3 points added if under the age of 50 years) improved the area under the curve to 0.8. This score was defined as the Persistency Index (possible score of 0-15). The Youden Index was used to identify the optimal cut point Persistency Index score for maximizing sensitivity and specificity.

Results: Using a development cohort of 215 subjects, the severity (Pelvic Floor Distress Index 5) and persistent nature (Female Genitourinary Pain Index 5) of the sensation of incomplete bladder emptying and dyspareunia (Female Genitourinary Pain Index 2b) were the most discriminatory characteristics of the myofascial urinary frequency syndrome group, which were combined with age to create the Persistency Index. The Persistency Index performed well in a validation cohort of 719 patients with various lower urinary tract symptoms, including overactive bladder (n=285), interstitial cystitis/bladder pain syndrome (n=53), myofascial urinary frequency syndrome (n=111), controls (n=209), and unknown diagnoses (n=61), exhibiting an area under the curve of 0.74. A Persistency Index score ≥7 accurately identified patients with myofascial urinary frequency syndrome from an unselected population of individuals with lower urinary tract symptoms with 80% sensitivity and 61% specificity. A combination of the Persistency Index with the previously defined Bladder Pain Composite Index and Urge Incontinence Composite Index separated a population of women seeking care for lower urinary tract symptoms into groups consistent with overactive bladder, interstitial cystitis/bladder pain syndrome, and myofascial urinary frequency syndrome phenotypes with an overall diagnostic accuracy of 82%.

Conclusion: Our study recommends a novel screening method for patients presenting with lower urinary tract symptoms to identify patients with myofascial urinary frequency syndrome. As telemedicine becomes more common, this index provides a way of screening for myofascial urinary frequency syndrome and initiating pelvic floor physical therapy even before a confirmatory pelvic examination.

Keywords: benign urological conditions; interstitial cystitis; lower urinary tract symptoms; nomogram; overactive bladder; persistency.