Background: Patients with myofascial pelvic floor dysfunction often present with lower urinary tract symptoms (LUTS), such as urinary frequency, urge, and bladder pressure. While easily confused with other lower urinary tract disorders, this constellation of symptoms, dubbed myofascial frequency syndrome (MFS) is distinct from other causes of LUTS and responds best to pelvic floor physical therapy. A detailed pelvic floor myofascial exam performed by a skilled provider is currently the only diagnostic method to identify MFS. Despite a high impact on quality of life, low awareness of this condition with the lack of objective diagnostic tests leads to the frequent mis- or under-diagnosis of this population. Objective: To develop a screening measure to identify patients with MFS (bothersome LUTS secondary to myofascial pelvic floor dysfunction) from patient-reported symptoms. Study Design: A homogenous population of patients with MFS was identified by provider diagnosis from a tertiary urogynecology practice and verified by standardized pelvic floor myofascial exam and pelvic floor electromyography. We utilized Least Angle Shrinkage and Selection Operator (LASSO) to identify candidate features from the OAB-q, fGUPI, and PFDI questionnaires predictive of MFS in a pooled population also containing subjects with overactive bladder (OAB, n=42), interstitial cystitis/bladder pain syndrome (IC/BPS, n=51), and asymptomatic controls (n = 54) (Derivation cohort). A simple summated score of the most predictive questions using the original scaling of the PFDI5 (0 to 4) and GUPI5 (0 to 5) and modified scaling of fGUPI2B (0 or 3) had an Area Under the Curve (AUC) of 0.75. As MFS was more prevalent in younger subjects, inclusion of an age penalty (3 points added if under age 50) improved the AUC to 0.8. This score, defined as the Persistency Index (PI) (possible score 0-15), performed well in the evaluation of a Validation cohort of 719 patients with a variety of LUTS, including OAB (n=285), IC/BPS (n=53), MFS (n=111), and unknown diagnoses (n=61), exhibiting a similar AUC of 0.79. Youden’s Index was used to identify the optimal cut point PI score for maximizing sensitivity and specificity. Results: The severity (PFDI5) and persistent nature (fGUPI5) of incomplete bladder emptying as well as dyspareunia (fGUPI2b) were the most discriminatory characteristics of the MFS group, which were combined with age to create the PI. A PI score greater than or equal to 7 accurately identified patients with MFS from an unselected population of individuals with LUTS with 80% sensitivity and 61% specificity (Table 1). Combination of the PI with the previously-defined bladder pain composite index (BPCI) and urge incontinence composite index (UICI) separated a population of women seeking care for LUTS into groups consistent with OAB, IC/BPS, and MFS phenotypes with an overall diagnostic accuracy of 82%. Conclusions: We propose a novel screening method for patients presenting with LUTS complaints to identify patients with myofascial frequency syndrome. As telemedicine becomes more common, this index provides a way of identifying these patients without the need for a detailed pelvic exam.