BackgroundClinical evaluation of male lower urinary tract symptoms (MLUTS) in secondary care uses a range of assessments. It is unknown how MLUTS evaluation influences outcome of therapy recommendations and choice, notably urodynamics (UDS; filling cystometry and pressure flow studies). ObjectiveTo report participants’ sociodemographic and clinical characteristics, and initial diagnostic findings of the Urodynamics for Prostate Surgery Trial; Randomised Evaluation of Assessment Methods (UPSTREAM). UPSTREAM is a randomised controlled trial evaluating whether symptoms are noninferior and surgery rates are lower if UDS is included. Design, setting, and participantsA total of 820 men (≥18 yr of age) seeking treatment for bothersome LUTS were recruited from 26 National Health Service hospital urology departments. InterventionCare pathway based on routine, noninvasive tests (control) or routine care plus UDS (intervention arm). Outcome measurements and statistical analysisThe primary outcome is International Prostate Symptom Score (IPSS) and the key secondary outcome is surgery rates 18 mo after randomisation. International Consultation on Incontinence Questionnaires were captured for MLUTS, sexual function, and UDS satisfaction. Baseline clinical and patient-reported outcome measures (PROMs), and UDS findings were informally compared between arms. Trends across age groups for urinary and sexual PROMs were evaluated with a Cuzick’s test, and questionnaire items were compared using Pearson’s correlation coefficient. Results and limitationsStorage LUTS, notably nocturia, and impaired sexual function are prominent in men being assessed for surgery. Sociodemographic and clinical evaluations were similar between arms. Overall mean IPSS and quality of life scores were 18.94 and 4.13, respectively. Trends were found across age groups, with older men suffering from higher rates of incontinence, nocturia, and erectile dysfunction, and younger men suffering from increased daytime frequency and voiding symptoms. Men undergoing UDS testing expressed high satisfaction with the procedure. ConclusionsMen being considered for surgery have additional clinical features that may affect treatment decision making and outcomes, notably storage LUTS and impaired sexual function. Patient summaryWe describe initial assessment findings from a large clinical study of the treatment pathway for men suffering with bothersome urinary symptoms who were referred to hospital for further treatment, potentially including surgery. We report the patient characteristics and diagnostic test results, including symptom questionnaires, bladder diaries, flow rate tests, and urodynamics.