Every year, roughly 880 men with urinary symptoms will undergo a simple urine flow test and a bladder ultrasound in their GP surgery, then have a thin catheter fed into their bladder to measure pressure during filling and voiding. The goal is to build a statistical decision tool that tells GPs, from those basic tests alone, whether a man’s problem is an overactive bladder muscle, a blocked outlet, or a weak pump—without needing the invasive catheter test for every patient. Currently, GPs lack a reliable way to distinguish these three conditions without referring men to a specialist for urodynamics, a test that is uncomfortable, costly, and not routinely available in primary care. This leads to misdiagnosis, delayed treatment, and unnecessary referrals. If the tool proves accurate, it could let GPs diagnose and manage most men with lower urinary tract symptoms in the surgery, reserving specialist referral only for complex cases. That would reduce waiting lists, cut NHS costs, and spare thousands of men an invasive procedure each year. The study also compares real-world referral rates from a national database to those guided by the new tool, giving a concrete measure of impact on the health system.
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DESIGN: Diagnostic accuracy study SETTING: Primary care and community. TARGET POPULATION: Men consulting their GP for LUTS. INCLUSION/EXCLUSION CRITERIA: LUTS from a defined list, with infection or prostate cancer judged unlikely. Able to undergo index and reference tests. Men having current or previously planned active treatment for Male LUTS excluded. HEALTH TECHNOLOGIES BEING ASSESSED: Diagnostic statistical decision aid combining variables from simple tests to give diagnosis and treatment recommendation. Reference standard is urodynamics whereby bladder pressure is monitored during bladder filling and voiding by a thin catheter passed into the bladder. MEASUREMENT OF COSTS AND OUTCOMES: Predictive value of index tests used individually or in combination for each of three diagnoses established by the reference test: detrusor overactivity during filling; bladder outlet obstruction during voiding; and detrusor underactivity during voiding, assessed by regression analysis. Diagnostic accuracy validated by measuring sensitivity and specificity for diagnoses established by the reference test reported to standard criteria. Rates of referral from the CPRD dataset will be compared to that from the study population with GPs guided by index and reference test results. Qualitative analysis of interview data to map out future adoption. SAMPLE SIZE: We require 350 men for the model development cohort and 325 for the validation cohort giving a total of 675 men inflated to 880 men to allow for those who do not complete the protocol. For development we specified an event per variable (EPV) rate of five, assumed the lowest prevalent diagnosis to be detrusor underactivity (16%) and 11 variables would be in the model. For this diagnosis a cohort of 350 men would provide 56 events fulfilling the conditions at an EPV of five. DIFFERENCE BETWEEN CURRENT AND PLANNED CARE PATHWAYS: The NICE pathway will be the standard. Study participants will undergo assessment recommended for primary care by NICE. In addition, urine flow rate and residual urine estimation; optional in the NICE pathway and not routine in primary care, will be included. All men in the study will undergo urodynamics as the reference test for diagnostic accuracy; this is a specialist test in the NICE pathway. All results will be given to the GP with the diagnosis and recommended management options to decide on further care. PROJECT TIMETABLE AND RECRUITMENT RATE: We plan a 36-month study with a 6-month set up and pilot phase, a 24-month recruitment window and 6 months for analysis, write up and prototype testing. To collect 675 datasets assuming 20-25% attrition, we will recruit 880 men at a rate of 37 per month. Assuming a 25% consent to participate rate and an incidence of 2 men/practice/month (CPRD 2014) we should include 75 GP practices inflated to 100 to allow for non-recruitment to identify sufficient men. These will be managed through 3 research network hubs. Previous primary care studies led by our trials unit suggest set-up of 100 GP practices over 12 months is feasible. EXPERTISE IN TEAM: We have necessary skills in functional urology including reference test reporting (CH/RP/MD/AB), clinical measurement (MD/AB), test evaluation methodology (JD/JA), statistics (JD/YT), a CTU experienced in conducting primary care studies (KH/ET-J), qualitative methodology (NJ-W, AE), experience in running multi-centre studies in secondary (RP/CH) and primary care (AE/HA/ET-J, primary care leads and input from the user perspective (JR/TS).
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