PROJECT SUMMARY/ABSTRACT While the overactive bladder (OAB) is a well-researched and common urologic condition, its apparent opposite, the underactive bladder (UAB), remains neglected and poorly understood. UAB is increasingly recognized as a likely cause of lower urinary tract symptoms (LUTS), is commonly encountered in clinical practice, and severely impacts a patient's quality of life. If undiagnosed and untreated, UAB can lead to significant morbidity and may be life threatening. Epidemiologic research is considered a necessary step towards development of promising treatment modalities, but the present state of this research has been characterized as ?rudimentary?. The underlying pathophysiology of UAB remains poorly understood and its objective characterization uncertain. To begin to fill knowledge gaps surrounding UAB we propose research with two logically related phases: During Phase l we will complete focused statistical/epidemiologic analyses which cost-efficiently employ data from a large internationally respected urologic cohort study?the Boston Area Community Health (BACH) survey. These analyses will focus on the hypothesized and pathophysiologically plausible association of a range of potential risk factors with suspected symptomatic UAB: data on numerous factors are already available and grouped into conceptually distinct domains (socio-demographic, anthropometric/life events, nutrition, comorbidities, surgical interventions and medications). Because of likely gender-specific phenotypes we will consider symptomatic UAB separately in women and men. We will also examine unmet UAB need, how UAB overlaps with other urologic symptoms and whether UAB is predictive of (a sentinel event for) subsequent disease. Phase ll logically follows with the construction and clinical validation of a brief self- administered multidimensional UAB risk assessment tool, which will integrate clinically informative factors from both phases. Scale development and validation have been planned in detail and include item development and cognitive testing, and formal psychometric assessment, including scoring guidelines and validated diagnostic cutpoints for UAB. Upon completion of both phases (epidemiologic analyses and validated UAB screener development) we will publish results in top tier professional journals (to gain scientific acceptability) and present results at major clinical meetings (to gain clinical acceptability). In the age of online health information seeking, patient empowerment and shared decision making, this evidence-based tool will provide at-risk UAB patients useful information to trigger primary care providers and urologists towards more appropriate diagnosis and effective management of UAB. The tool will also provide a means to cost-efficiently prescreen potentially eligible UAB patients for future RCTs of promising interventions.