A NOMOGRAM TO CLASSIFY MEN WITH LOWER URINARY TRACT SYMPTOMS USING URINE FLOW AND NONINVASIVE MEASUREMENT OF BLADDER PRESSURE

Is the time right for a new initiative in mathematical modeling of the lower urinary tract? ICI-RS 2023

INTRODUCTION

A session at the 2023 International Consultation on Incontinence - Research Society (ICI-RS) held in Bristol, UK, focused on the question: Is the time right for a new initiative in mathematical modeling of the lower urinary tract (LUT)? The LUT is a complex system, comprising various synergetic components (i.e., bladder, urethra, neural control), each with its own dynamic functioning and high interindividual variability. This has led to a variety of different types of models for different purposes, each with advantages and disadvantages.

METHODS

When addressing the LUT, the modeling approach should be selected and sized according to the specific purpose, the targeted level of detail, and the available computational resources. Four areas were selected as examples to discuss: utility of nomograms in clinical use, value of fluid mechanical modeling, applications of models to simplify urodynamics, and utility of statistical models.

RESULTS

A brief literature review is provided along with discussion of the merits of different types of models for different applications. Remaining research questions are provided.

CONCLUSIONS

Inadequacies in current (outdated) models of the LUT as well as recent advances in computing power (e.g., quantum computing) and methods (e.g., artificial intelligence/machine learning), would dictate that the answer is an emphatic "Yes, the time is right for a new initiative in mathematical modeling of the LUT."

The diagnostic value of non-invasive methods for diagnosing bladder outlet obstruction in men with lower urinary tract symptoms: A meta-analysis

Purpose

We conducted the first meta-analysis to determine the diagnostic value of non-invasive methods for diagnosing bladder outlet obstruction (BOO) in men with lower urinary tract symptoms (LUTS).

Methods

We searched a range of databases for relevant publications up to June 2022, including PubMed, Embase, Web of Science, and the Cochrane Library. Retrieved studies were then reviewed for eligibility and data were extracted. The risk of bias (RoB) was assessed using the QUADAS-2 tool. We then performed a formal meta-analysis to evaluate the accuracy of various non-invasive methods for diagnosing BOO in men.

Results

We identified 51 eligible studies including 7,897 patients for meta-analysis. The majority of the studies had a low overall RoB. Detrusor wall thickness (DWT) (pooled sensitivity (SSY): 71%; specificity (SPY): 88%; diagnostic odds ratio (DOR): 17.15; area under curve (AUC) 0.87) and the penile cuff test (PCT) (pooled SSY: 87%; SPY: 78%; DOR: 23.54; AUC: 0.88) showed high accuracy for diagnosing BOO. Furthermore, data suggested that DWT had the highest pooled SPY (0.89), DOR (32.58), and AUC (0.90), when using 2 mm as the cut-off.

Conclusion

Of the non-invasive tests tested, DWT and PCT had the highest levels of diagnostic accuracy for diagnosing BOO in men with LUTS. DWT, with a 2 mm cut-off, had the highest level of accuracy. These two methods represent good options as non-invasive tools for evaluating BOO in males.

Use of the penile cuff test to diagnose bladder outlet obstruction: A systematic review and meta-analysis

PURPOSE

Among noninvasive modalities for assessing bladder outlet obstruction (BOO), the penile cuff test (PCT) is the most used in clinical practice. The purpose of this review was to evaluate the performance of PCT in diagnosing and managing BOO.

MATERIALS AND METHODS

PubMed, Scopus, CINAHL, Embase, Cochrane Library, and Web of Science were searched for studies investigating use of PCT for BOO. Studies evaluating diagnostic parameters, inter-observer agreements, or treatment outcomes using PCT were included. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol was followed (PROSPERO ID: CRD42022300047). A proportional meta-analysis was done for diagnostic accuracy proportions. The Egger's and the Begg-Mazumdar rank-correlation tests were used to assess publication bias. Risk of bias was assessed using the Gradings of Recommendations, Assessment, Development, and Evaluations (GRADE) criteria.

RESULTS

Of the 272 articles retrieved, 17 were included in qualitative synthesis and meta-analysis was performed on five studies (comprising 448 patients). Two studies evaluating inter-observer agreement demonstrated 95% agreement and five studies evaluating procedures reported a 66%-80% surgical success rate on obstructed patients using PCT. From the proportional meta-analysis, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 0.85 (95% CI 0.71-0.95) 0.78 (95% CI 0.67-0.87), 0.74 (95% CI 0.52-0.91), and 0.87 (95% CI 0.73-0.96), respectively. Publication bias was noted for PPV but not for sensitivity, specificity, or NPV. Based on the GRADE criteria, there were two low, six moderate, and nine high-quality studies.

CONCLUSIONS

PCT performs sufficiently in diagnosing and managing BOO. However, due to variability in obstruction criteria assessment, more studies comparing diagnostic criteria are warranted.

Comparison of Penile Cuff Test and Conventional Urodynamic Study Prior to Photoselective Vaporization of Prostate for Benign Prostate Hyperplasia Using a 120 W GreenLight High Performance System Laser

Background: We compared the utility of the penile cuff test (PCT) and the conventional urodynamic study (UDS) for the preoperative assessment of patients undergoing scheduled photoselective vaporization of the prostate (PVP) for benign prostate hyperplasia (BPH). Methods: Fifty-nine patients with voiding lower urinary tract symptoms (LUTS) underwent a simultaneous PCT and conventional UDS before PVP. The modified International Continence Society (ICS) nomogram was used to confirm bladder outlet obstruction after measuring maximum urinary flow rate and highest pressure at flow interruption. The PCT and UDS results, in terms of modified ICS nomogram predictions, were compared. Their sensitivities, specificities, and positive and negative predictive values were calculated. Results: Thirty-six patients were diagnosed as obstructed and 23 as non-obstructed/equivocal using the modified ICS nomogram during the PCT. All 36 of the first group were confirmed as obstructed by UDS. Of the 23 diagnosed as non-obstructed/equivocal by the PCT, 14 were confirmed to be non-obstructed by UDS, with nine diagnosed as obstructed. The PCT showed a sensitivity of 80% and a specificity of 100%. The positive and negative predictive values were 100% and 60.9%, respectively. Conclusions: In conclusion, despite our small number of patients, the PCT’s high sensitivity and specificity suggest that it may provide diagnostic information about bladder outlet obstruction before PVP for patients with voiding LUTS. Evidently, the PCT has the potential to be used for some patients as a screening alternative to invasive UDS.

Vorticity in lower urinary tract can be assessed and associates with urinary tract morphology in men

OBJECTIVES

The aim of this study is to develop a method to evaluate the fluid dynamics of urine flow in the lower urinary tract (LUT), especially that of vorticity.

MATERIALS AND METHODS

This investigation included three sub-studies to demonstrate urine flow in the entire LUT. First, we attempted to observe vorticity generation in the urinary bladder during spontaneous voiding using transabdominal color Doppler ultrasonography (CDUS). Second, we performed transrectal CDUS to evaluate the vorticity of urine flow in the prostatic urethra. Patients with prostate cancer were enrolled before robotic surgery and divided into the vorticity and non-vorticity groups based on CDUS findings for comparisons of longitudinal urethral diameter and prostatic urethral angle. Third, the vorticity of the voided urine stream was observed using a high-speed video-camera. Micturition was done in a standing position while synchronously monitored for urine flow using uroflowmetry.

RESULTS

Vorticity formation could be dynamically demonstrated in the urinary bladder and prostatic urethra using CDUS. The prostatic urethral angle of the vorticity group was more than that of the non-vorticity group. High-speed video recording could clearly capture vorticity and spiral shape generation in voided urine. The distance from the external urethral orifice to the first twist changed in accordance with urine flow rate.

CONCLUSIONS

In a series of sub-studies, this investigation proved vorticity generation in the LUT and voided urine. Vorticity was detectable in the LUT and in voided urine using CDUS and a high-speed video-camera. Vorticity generation might be associated with urethral morphology.

The mechanical stop test and isovolumetric detrusor contractile reserve are associated with immediate spontaneous voiding after transurethral resection of prostate

PURPOSE

To identify urodynamic factors associated with the mechanical stop test and immediate spontaneous voiding following transurethral resection of prostate (TURP).

METHODS

We identified 90 men who underwent TURP over a 12-month period. Forty-three (mean age 68 years) underwent urodynamic evaluation prior to TURP. Isovolumetric detrusor contractile pressure (P_iso) was obtained using the mechanical stop test during the voiding phase, and used to calculate detrusor contractile reserve (P_res = P_iso - P_det@Q_max). Primary outcome was spontaneous voiding after TURP.

RESULTS

Preoperative catheter-free spontaneous voiding was present in 63% of men (27/43) with a urodynamic (mean ± SD): Q_max 6.2 ± 2.7 mL/s, P_det@Q_max 102 ± 47 cmH₂O, P_iso 124 ± 49 cmH₂O, P_res 22 ± 16 cmH₂O, bladder outlet obstruction index (BOOI) 90 ± 49, and bladder contractility index (BCI) 132 ± 44. The remaining 16 catheter-dependent men demonstrated a urodynamic (mean ± SD): Q_max 3.6 ± 3.3 mL/s, P_det@Q_max 87 ± 38 cmH₂O, P_iso 99 ± 51 cmH₂O, P_res 10 ± 18 cmH₂O, BOOI 82 ± 36, and BCI 106 ± 48. Following TURP, 67% of men voided spontaneously with their first void trial, and in receiver operator analysis of urodynamic measures (P_det@Q_max, P_iso, P_res, BOOI and BCI), only P_res was significantly associated with immediate spontaneous voiding after TURP (threshold P_res ≥ 9 cmH₂O, AUC = 0.681, p = 0.035).

CONCLUSIONS

In men who underwent TURP, a P_res ≥ 9 cmH₂O was associated with immediate spontaneous voiding and may be easily incorporated into the postoperative pathway.

New Diagnostics for Male Lower Urinary Tract Symptoms

PURPOSE OF REVIEW

Lower urinary tract symptoms (LUTS) is a common constellation of symptoms that affect the aging male population with an astonishing prevalence. New technology and new uses of established technology are being used to help further evaluate LUTS in the male population and help guide treatment options. This review focuses on the developments and future directions in diagnostic modalities for evaluation of male LUTS, focusing on evaluation of both the filling and voiding phases of micturition.

RECENT FINDINGS

New techniques in evaluating the voiding phase include penile cuff test, external pressure sensing condom catheter, ultrasound measurement of detrusor wall thickness, ultrasound measurement of intravesical prostatic protrusion, doppler ultrasound and NIRS technology. Evaluation of the filling phase is still undergoing much development and requires additional validation studies. The techniques undergoing evaluation include sensation meters during UDS, assessing bladder micromotion and wall rhythm, assessing detrusor wall biomechanics, ultrasound measurement of detrusor wall thickness, pelvic doppler ultrasound, as well as functional brain imaging including fNIRS and fMRI.

SUMMARY

The development of novel, non-invasive, diagnostic tools have the potential for better evaluation of LUTS with earlier and enhanced treatments. This will likely improve the quality of life for men with LUTS.

Correlation of tools for objective evaluation of infravesical obstruction of men with lower urinary tract symptoms

Purpose

To identify how the most frequently used parameters in daily clinical practice diagnosing bladder outlet obstruction (BOO) due to benign prostate hyperplasia (BPH) correlate to each other.

Materials and methods

The study included 452 patients with lower urinary tract symptoms (LUTS) of the UNICAMP urology outpatient clinic of LUTS. Inclusion criteria: patients with BOO due to BPH who agreed to participate in the study. Exclusion criteria: patients with urinary tract infection, neurological diseases that compromised the lower urinary tract, prior prostatic surgery, radiotherapy or urethral stenosis. Patient assessment: history, international prostate symptoms score (IPSS), nocturnal quality of life score (NQoL) questionnaires, physical and digital rectal examination (DRE), PSA, transabdominal ultrasound with intravesical prostate protrusion (IPP), post-mictional residue and free uroflowmetry.

Results

There was no strong Spearman correlation among the studied variables. The only moderate correlations occurred between IPSS and NQoL (p <0001; c=0.56) and between IPP and prostate volume (p <0001; c=0.57). Weak correlations between IPP and post-mictional residue (p <0001; c=0.31) and free uroflowmetry (p <0001; c=-0.26); and between IPSS and free uroflowmetry (p <0001, c=-0.21) were observed.

Conclusion

In this study, we found moderate, weak, very weak and absent correlation among the various parameters used in the diagnosis and management of BOO due to BPH. As the value of these tools is variable, the creation of a logical and objective algorithm was not possible and the treatment is based on the interpretation of clinical symptoms.

Development and validation of a clinical nomogram predicting bladder outlet obstruction via routine clinical parameters in men with refractory nonneurogenic lower urinary tract symptoms

We aimed to develop and validate a clinical nomogram predicting bladder outlet obstruction (BOO) solely using routine clinical parameters in men with refractory nonneurogenic lower urinary tract symptoms (LUTS). A total of 750 eligible patients ≥50 years of age who had previously not responded (International Prostate Symptom Score [IPSS] improvement <4 points) to at least three different kinds of LUTS medications (including a-blocker) for the last 6 months were evaluated as subcohorts for nomogram development (n = 570) and for split-sample validation (n = 180). BOO was defined as Abrams–Griffiths number ≥40, or 20–39.9 with a slope of linear passive urethral resistance ratio >2 cmH₂O ml⁻¹ s⁻¹. A stepwise multivariable logistic regression analysis was conducted to determine the predictors of BOO, and b-coefficients of the final model were selected to create a clinical nomogram. The final multivariable logistic regression model showed that age, IPSS, maximum urinary flow rate, postvoid residual volume, total prostate volume, and transitional zone index were significant for predicting BOO; these candidates were used to develop the final nomogram. The discrimination performance of the nomogram was 88.3% (95% CI: 82.7%–93.0%, P < 0.001), and the nomogram was reasonably well-fitted to the ideal line of the calibration plot. Independent split-sample validation revealed 80.9% (95% CI: 75.5%–84.4%, P < 0.001) accuracy. The proposed BOO nomogram based solely on routine clinical parameters was accurate and validated properly. This nomogram may be useful in determining further treatment, primarily focused on prostatic surgery for BOO, without impeding the detection of possible BOO in men with LUTS that is refractory to empirical medications.

Can the Penile Cuff Test Predict the Outcome of Holmium Laser Enucleation of the Prostate for Benign Prostatic Obstruction?

OBJECTIVE

To determine whether the penile cuff test can predict surgical outcomes prior to Holmium laser enucleation of the prostate for benign prostatic obstruction.

METHODS

Men scheduled to undergo Holmium laser enucleation of the prostate were enrolled in this study, and all patients underwent the penile cuff test prior to and 3 months after surgery. Patients were categorized as obstructed, nonobstructed, or uncertain by nomogram. Surgical outcomes were assessed by evaluating changes in their international prostate symptom score, quality of life index, and maximum flow rate preoperatively and 3 months postoperatively. The proportion of patients with good outcomes was compared among nomogram-classified groups, and postoperative changes in position on the nomogram were assessed.

RESULTS

A total of 125 patients were analyzed. After surgery, the overall treatment efficacy and symptomatic treatment efficacy were not different between obstructed and nonobstructed patients. However, the maximum flow rate and quality of life score were significantly higher after surgery in obstructed patients compared to nonobstructed patients. After surgery, 75.7% of patients with obstruction and 63.6% of patients categorized as uncertain for obstruction transitioned to the nonobstructed group, while 77.3% of nonobstructed patients remained in the nonobstructed group.

CONCLUSION

The penile cuff test can be used in patients with bladder outlet obstruction to predict good functional outcome and improved quality of life following treatment with Holmium laser enucleation. After Holmium laser enucleation of the prostate, the majority of patients were classified as nonobstructed.

Minimally invasive measurement of vesical pressure for diagnosis of infravesical obstruction

AIMS

This study was focused on the clinical test of an improved and portable version of a previously described urethral connector (UC), designed for minimally invasive measurement of vesical pressure and diagnosis of infravesical obstruction in men.

METHODS

The conventional pressure-flow study (PFS) and the test with the new version of UC were applied to individuals reporting lower urinary tract symptoms (LUTS), who were then classified as obstructed or non-obstructed/equivocal based on the bladder outlet obstruction index (BOOI) from PFS data. Two-way analysis of variance was used to compare the values of urine flow rate and vesical pressure between methods and diagnoses.

RESULTS

Vesical pressure and urine flow values were not significantly different between methods (P > 0.05), while the former was greater in the group classified as obstructed.

CONCLUSION

The present results showed that the UC test can support the diagnosis of infravesical obstruction in a comparable way as that of the conventional urodynamic method, however with the advantages of simplicity and minimal invasiveness, having thus the potential to be an alternative method for long term follow-up of individuals reporting LUTS.

Male bladder outlet obstruction: Time to re-evaluate the definition and reconsider our diagnostic pathway? ICI-RS 2015

The diagnosis of bladder outlet obstruction (BOO) in the male is dependent on measurements of pressure and flow made during urodynamic studies. The procedure of urodynamics and the indices used to delineate BOO are well standardized largely as a result of the work of the International Continence Society. The clinical utility of the diagnosis of BOO is however, less well defined and there are several shortcomings and gaps in the currently available medical literature. Consequently the International Consultation on Incontinence Research Society (ICI-RS) held a think tank session in 2015 entitled "Male bladder outlet obstruction: Time to re-evaluate the definition and reconsider our diagnostic pathway?" This manuscript details the discussions that took place within that think tank setting out the pros and cons of the current definition of BOO and exploring alternative clinical tests (alone or in combination) which may be useful in the future investigation of male patients with lower urinary tract symptoms. The think tank panel concluded that pressure-flow studies remain the diagnostic gold-standard for BOO although there is still a lack of high quality evidence. Newer, less invasive, investigations have shown promise in terms of diagnostic accuracy for BOO but similar criticisms can be levelled against these tests. Therefore, the think tank suggests further research with regard to these alternative indicators to determine their clinical utility.

Systematic Review of the Performance of Noninvasive Tests in Diagnosing Bladder Outlet Obstruction in Men with Lower Urinary Tract Symptoms

CONTEXT

Several noninvasive tests have been developed for diagnosing bladder outlet obstruction (BOO) in men to avoid the burden and morbidity associated with invasive urodynamics. The diagnostic accuracy of these tests, however, remains uncertain.

OBJECTIVE

To systematically review available evidence regarding the diagnostic accuracy of noninvasive tests in diagnosing BOO in men with lower urinary tract symptoms (LUTS) using a pressure-flow study as the reference standard.

EVIDENCE ACQUISITION

The EMBASE, MEDLINE, Cochrane Database of Systematic Reviews, Cochrane Central, Google Scholar, and WHO International Clinical Trials Registry Platform Search Portal databases were searched up to May 18, 2016. All studies reporting diagnostic accuracy for noninvasive tests for BOO or detrusor underactivity in men with LUTS compared to pressure-flow studies were included. Two reviewers independently screened all articles, searched the reference lists of retrieved articles, and performed the data extraction. The quality of evidence and risk of bias were assessed using the QUADAS-2 tool.

EVIDENCE SYNTHESIS

The search yielded 2774 potentially relevant reports. After screening titles and abstracts, 53 reports were retrieved for full-text screening, of which 42 (recruiting a total of 4444 patients) were eligible. Overall, the results were predominantly based on findings from nonrandomised experimental studies and, within the limits of such study designs, the quality of evidence was typically moderate across the literature. Differences in noninvasive test threshold values and variations in the urodynamic definition of BOO between studies limited the comparability of the data. Detrusor wall thickness (median sensitivity 82%, specificity 92%), near-infrared spectroscopy (median sensitivity 85%, specificity 87%), and the penile cuff test (median sensitivity 88%, specificity 75%) were all found to have high sensitivity and specificity in diagnosing BOO. Uroflowmetry with a maximum flow rate of <10ml/s was reported to have lower median sensitivity and specificity of 68% and 70%, respectively. Intravesical prostatic protrusion of >10mm was reported to have similar diagnostic accuracy, with median sensitivity of 68% and specificity of 75%.

CONCLUSIONS

According to the literature, a number of noninvasive tests have high sensitivity and specificity in diagnosing BOO in men. However, although the majority of studies have a low overall risk of bias, the available evidence is limited by heterogeneity. While several tests have shown promising results regarding noninvasive assessment of BOO, invasive urodynamics remain the gold standard.

PATIENT SUMMARY

Urodynamics is an accurate but potentially uncomfortable test for patients in diagnosing bladder problems such as obstruction. We performed a thorough and comprehensive review of the literature to determine if there were less uncomfortable but equally effective alternatives to urodynamics for diagnosing bladder problems. We found that some simple tests appear to be promising, although they are not as accurate. Further research is needed before these tests are routinely used in place of urodynamics.

Urodynamics for Prostate Surgery Trial; Randomised Evaluation of Assessment Methods (UPSTREAM) for diagnosis and management of bladder outlet obstruction in men: study protocol for a randomised controlled trial

Background

Lower urinary tract symptoms (LUTS) comprise storage symptoms, voiding symptoms and post-voiding symptoms. Prevalence and severity of LUTS increase with age and the progressive increase in the aged population group has emphasised the importance to our society of appropriate and effective management of male LUTS. Identification of causal mechanisms is needed to optimise treatment and uroflowmetry is the simplest non-invasive test of voiding function. Invasive urodynamics can evaluate storage function and voiding function; however, there is currently insufficient evidence to support urodynamics becoming part of routine practice in the clinical evaluation of male LUTS.

Design

A 2-arm trial, set in urology departments of at least 26 National Health Service (NHS) hospitals in the United Kingdom (UK), randomising men with bothersome LUTS for whom surgeons would consider offering surgery, between a care pathway based on urodynamic tests with invasive multichannel cystometry and a care pathway based on non-invasive routine tests. The aim of the trial is to determine whether a care pathway not including invasive urodynamics is no worse for men in terms of symptom outcome than one in which it is included, at 18 months after randomisation. This primary clinical outcome will be measured with the International Prostate Symptom Score (IPSS). We will also establish whether inclusion of invasive urodynamics reduces rates of bladder outlet surgery as a main secondary outcome.

Discussion

The general population has an increased life-expectancy and, as men get older, their prostates enlarge and potentially cause benign prostatic obstruction (BPO) which often requires surgery. Furthermore, voiding symptoms become increasingly prevalent, some of which may not be due to BPO. Therefore, as the population ages, more operations will be considered to relieve BPO, some of which may not actually be appropriate. Hence, there is sustained interest in the diagnostic pathway and this trial could improve the chances of an accurate diagnosis and reduce overall numbers of surgical interventions for BPO in the NHS. The morbidity, and therapy costs, of testing must be weighed against the cost saving of surgery reduction.

Trial registration

Controlled-trials.com - ISRCTN56164274 (confirmed registration: 8 April 2014).

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-1087-1) contains supplementary material, which is available to authorized users.

The role of noninvasive penile cuff test in patients with bladder outlet obstruction

PURPOSE

The aim of this study was to compare the penile cuff test (PCT) and standard pressure-flow study (PFS) in patients with bladder outlet obstruction.

MATERIALS AND METHODS

A total of 58 male patients with moderate to severe lower urinary tract symptoms (LUTS) were selected. Seven patients were excluded; thus, 51 patients were finally enrolled. Each of the patients underwent a PCT and a subsequent PFS. The sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and likelihood ratio were calculated. Chi-square and Fisher exact test were used to evaluate relationships between PCT results and maximal urine flow (Qmax); a p<0.05 was considered statistically significant.

RESULTS

The mean (±standard deviation) age of the study group was 65.5±10.4 years. Overall, by use of the PCT, 24 patients were diagnosed as being obstructed and 27 patients as unobstructed. At the subsequent PFS, 16 of the 24 patients diagnosed as obstructed by the PCT were confirmed to be obstructed, 4 were diagnosed as unobstructed, and the remaining 4 patients appeared equivocal. Of the 27 patients shown to be unobstructed by the PCT, 25 were confirmed to not be obstructed by PFS, with 13 equivocal and 12 unobstructed. Two patients were diagnosed as being obstructed. For detecting obstruction, the PCT showed an SE of 88.9% and an SP of 75.7%. The PPV was 66.7% and the NPV was 93%.

CONCLUSIONS

The PCT is a beneficial test for evaluating patients with LUTS. In particular, this instrument has an acceptable ability to reject obstruction caused by benign prostatic hyperplasia.

Correlation between penile cuff test and pressure-flow study in patients candidates for trans-urethral resection of prostate

Background

Aim of this study was to make a comparison between penile cuff test (PCT) and standard pressure-flow study (PFS) in the preoperative evaluation of patients candidates for trans-urethral resection of prostate (TURP) for benign prostatic obstruction (BPO).

Methods

We enrolled male patients with lower urinary tract symptoms candidates for TURP. Each of them underwent a PCT and a subsequent PFS. A statistical analysis was performed: sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), likelihood ratio and ratio of corrected classified were calculated. Fisher exact test was used to evaluate relationships between PCT and maximal urine flow (Q_max): a p-value < 0.05 was considered statistically significant.

Results

We enrolled 48 consecutive patients. Overall, at PCT 31 patients were diagnosed as obstructed and 17 patients as unobstructed. At the subsequent PFS, 21 out of 31 patients diagnosed as obstructed at PCT were confirmed to be obstructed; one was diagnosed as unobstructed; the remaining 9 patients appeared as equivocal. Concerning the 17 patients unobstructed at PCT, all of them were confirmed not to be obstructed at PFS, with 10 equivocal and 7 unobstructed. The rate of correctly classified patients at PCT was 79% (95%-CI 65%-90%). About detecting obstructed patients, PCT showed a SE of 100% and a SP of 63%. The PPV was 68%, while the NPV was 100%.

Conclusions

PCT can be an efficient tool in evaluating patients candidates for TURP. In particular, it showed good reliability in ruling out BPO because of its high NPV, with a high rate of correctly classified patients overall. Further studies on a huger number of patients are needed, including post-operative follow-up as well.

Voiding dysfunction due to detrusor underactivity: an overview

Detrusor underactivity (DUA) is defined as a voiding contraction of reduced strength and/or duration, which prolongs urination and/or prevents complete emptying of the bladder within a 'normal' period of time. This issue is associated with voiding and postmicturition urinary symptoms, and can predispose to urinary infections and acute urinary retention. The aetiology of DUA is influenced by multiple factors, including ageing, bladder outlet obstruction, neurological disease, and autonomic denervation. The true prevalence of this condition remains unknown, as most data come from referral populations. Urodynamic testing is used to diagnose the condition, either by assessing the relationship between bladder pressures and urinary flow, or by interrupting voiding to measure detrusor pressure change under isovolumetric conditions. Current treatments for DUA have poor efficacy and tolerability, and often fail to improve quality of life; muscarinic receptor agonists, in particular, have limited efficacy and frequent adverse effects. Bladder emptying might be achieved through Valsalva straining, and intermittent or indwelling catheterization, although sacral nerve stimulation can reduce dependency on catheterization. Novel stem-cell-based therapies have been attempted; however, new drugs that increase contractility are currently largely conceptual, and the complex pathophysiology of DUA, difficulty achieving organ specificity of treatment, the limited availability of animal models, and the subjective nature of current outcome measures must be addressed to facilitate the development of such agents.

Non-invasive urodynamics predicts outcome prior to surgery for prostatic obstruction

OBJECTIVE

To assess whether the penile cuff non-invasive urodynamic test serves as an effective diagnostic tool for predicting outcomes prior to disobstructive surgery for men presenting with voiding lower urinary tract symptoms. Patients with proven urodynamic obstruction do better after surgery. The current gold standard, invasive pressure-flow studies, imposes cost, resource demand, discomfort and inconvenience to patients.

PATIENTS AND METHODS

Patients undergoing surgery for prostatic obstruction at Palmerston North Hospital had pre-operative non-invasive urodynamics and completed an International Prostate Symptom Score (IPSS). Catheterised patients were excluded. Two months post-operatively they completed a further IPSS score. An improvement of seven or greater was defined as a clinically successful outcome. Results were compared with the outcome predicted by the nomogram supplied with the urodynamic device.

RESULTS

Data was obtained for 62 patients with mean age 70 years (range 49 to 86 years; SD 9 years). Follow-up was complete for all patients. Thirty-eight patients underwent transurethral resection and 24 holmium laser enucleation of the prostate. Mean IPSS score was 21 (range 5 to 35; SD 6) pre-operatively and 11 (range 1 to 31; SD 9) post-operatively. Thirty-five patients were predicted obstructed and 27 not obstructed. 94% of those predicted obstructed had a successful outcome (p < 0.01). 70% predicted as not obstructed did not have a successful outcome after surgery (p < 0.01).

CONCLUSION

The penile cuff test is an exciting adjunct in the decision to proceed to surgery for prostatic obstruction. Patients predicted to be obstructed have an excellent likelihood of a good surgical outcome, yet 30% of those shown not to be obstructed will still do well. Whilst numbers in our study are small, outcomes compare favourably with published results on invasive urodynamic methods.

The role of uroflowmetry in the assessment and management of men with lower urinary tract symptoms – revisiting the evidence

Uroflowmetry is variably used for the assessment of men with lower urinary tract symptoms (LUTS). There is discrepancy in practice guidelines regarding recommendations for use of uroflowmetry in the initial assessment of men with LUTS. To explain this discrepancy, we systematically reviewed relevant literature to detail currently available evidence and identify evidence gaps requiring further research. PubMED, EMBASE and Medline literature databases were searched for the period between January 1970 and July 2012 to identify articles pertaining to uroflowmetry and outcomes of treatment for men with LUTS. We identified 30 studies for inclusion – none of which had a randomised design. The majority of the studies were prospective or retrospective cohort studies with some cross-sectional and observational reports. The methodology of measurement and reporting urine flow rate has been standardised by reports from the International Continence Society. The current available literature on the reproducibility of urine flow rate is inconclusive and suggests that there may be variability between measurements for a number of different reasons and that repeated tests could be of value clinically. There is also general agreement that a Qmax cut-off of 10 ml/s−1 is suggestive of bladder outlet obstruction. Despite guideline recommendations, there remains a lack of high-quality evidence from studies with robust design to fully ascertain the clinical utility of uroflowmetry and its place in the care pathway for men with LUTS. Future well-designed studies should focus on this evidence gap.

The evidence for urodynamic investigation of patients with symptoms of urinary incontinence

Urodynamic studies are the gold standard to objectively diagnose dysfunction of the lower urinary tract. The widely available evidence for the clinical relevance is, however, fragmented. This article summarizes the published knowledge supporting the use of urodynamic studies in urinary incontinence in female, male and frail patients, as well as patients with relevant neurological disease. Five technological innovations are discussed briefly. Standard urodynamic cystometry can, on the basis of a solid body of evidence, objectively unveil the entire function of the lower urinary tract in all patients with urinary incontinence, regardless of the patients' perception of (ab-)normality of signs and or symptoms.

Urodynamic studies in adults: AUA/SUFU guideline

PURPOSE

The authors of this guideline reviewed the literature regarding use of urodynamic testing in common lower urinary tract symptoms. The findings are intended to assist clinicians in the appropriate selection of urodynamic tests, following an evaluation and symptom characterization.

MATERIALS AND METHODS

A systematic review of the literature using the MEDLINE® and EMBASE databases (searched from 1/1/90 to 3/10/11) was conducted to identify peer-reviewed publications relevant to using urodynamic tests for diagnosis, determining prognosis, guiding clinical management decisions and improving patient outcomes in patients with various urologic conditions. The review yielded an evidence base of 393 studies after application of inclusion/exclusion criteria. These publications were used to create the evidence basis for characterizing the statements presented in the guideline as Standards, Recommendations or Options. When sufficient evidence existed, the body of evidence for a particular treatment was assigned a strength rating of A (high), B (moderate) or C (low). In the absence of sufficient evidence, additional information is provided as Clinical Principles and Expert Opinion.

RESULTS

The evidence-based guideline statements are provided for diagnosis and overall management of common LUTS conditions.

CONCLUSIONS

The Panel recognizes that each patient presenting with LUTS is unique. This Guideline is intended to serve as a tool facilitating the most effective utilization of urodynamic testing as part of a comprehensive evaluation of patients presenting with LUTS.

[Predictive value of the penile cuff-test for the assessment of bladder outlet obstruction in men]

PURPOSE

To assess the diagnostic performances and the acceptability of the penile cuff test (PCT) which is a non invasive method for the evaluation of bladder outlet obstruction (BOO), in comparison with the pressure flow study (PFS), the actual gold-standard.

MATERIAL

Monocentric prospective study comparing the following subsets: "obstructed", "not obstructed" or "equivocal", deduced from PFS vs PCT, in 30 consecutive patients presenting with lower urinary tract symptoms. For the PCT, a cuff placed around the penis inflated automatically during the micturition, until flow rate interruption. The interruption cuff pressure revealed the isovolumetric bladder pressure (Pcuff-int). The data collected - Pcuff-int and maximum flow rate - were automatically reported on ICS modified nomogram.

RESULTS

With the PFS, 11 patients (39%) were classified "obstructed", six patients (22%) "non-obstructed" and 11 patients (39%) "equivocal". In 61% cases, the patient was classified in the same category by both techniques. The "obstructed positive predictive value" of the PCT was 82% and the "non-obstructed-equivocal negative predictive value" was 88%. The median acceptability visual analogic scale score was 1/10 (0-3) for the PCT whereas it was 5/10 (2-10) for the PFS. This difference was statistically significant (p=0.004).

CONCLUSION

The PCT was a reliable non-invasive tool for the diagnosis of BOO in male, in comparison with PFS. The predictive values of the PCT were relevant and its tolerance was better than PFS.

Correlation between intravesical pressure and prostatic obstruction grade using computational fluid dynamics in benign prostatic hyperplasia

An urodynamic test which measures various physiologic variables during voiding is generally used for accurate diagnosis of a bladder outlet obstruction (BOO) resulting from benign prostatic hyperplasia (BHP). However, this method is difficult to directly apply to all patients because it is an invasive test and many patients suffer from anxiety and embarrassment during the test. Thus, other diagnosis methods such as uroflowmetry and prostatic symptom score are performed to measure the degree of BOO prior to the urodynamic test, and it is necessary to construct a quantitative relationship among the obstruction level, the intravesical pressure, and the uroflow rate. The aim of this paper is to analyse the variation of intravesical pressure as a function of the extent of the obstruction and the uroflow rate from given information on the size of the bladder and the urodynamic test using a computational fluid dynamics approach. In order to analyse the intravesical pressure, a two-dimensional axisymmetric model of the bladder including a narrowed region, i.e. the prostatic obstruction, is created. Then the variation of the intravesical pressure is quantitatively obtained as a function of the magnitude of the uroflow rate and the extent of the obstruction. It is shown that the intravesical pressure significantly increases even for small obstructions and that at large obstructions it can reach values higher than 100 cm H2O, which is a dangerous value. It is shown that the intravesical pressure decreases as the uroflow rate decreases. This study can form the basis of a non-invasive test for the diagnosis of BHP.

The penile cuff test: A clinically useful non-invasive urodynamic investigation to diagnose men with lower urinary tract symptoms

Objectives:

To summarize the development of a novel non-invasive test to categorize voiding dysfunction in men complaining of lower urinary tract symptoms (LUTS) - the penile cuff test.

Methods:

The test involves the controlled inflation of a penile cuff during micturition to interrupt voiding and hence estimate isovolumetric bladder pressure (p_ves.isv). The validity, reliability, and clinical usefulness of the test were determined in a number of studies in men with LUTS.

Results:

The penile cuff test can be successfully performed in over 90% of men with LUTS. The reading of cuff pressure at flow interruption (p_cuff.int) gives a valid and reliable estimate of invasively-measured p_ves.isv and when combined with the reading for maximum flow rate obtained during the test (Q_max) produces an accurate categorization of bladder outlet obstruction (BOO). Use of this categorization prior to treatment allows improved prediction of outcome from prostatectomy.

Conclusion:

The penile cuff test fulfils the criteria as a useful clinical measurement technique applicable to the diagnosis and treatment planning of men with LUTS.

Review of invasive urodynamics and progress towards non-invasive measurements in the assessment of bladder outlet obstruction

OBJECTIVE

This article defines the need for objective measurements to help diagnose the cause of lower urinary tract symptoms (LUTS). It describes the conventional techniques available, mainly invasive, and then summarizes the emerging range of non-invasive measurement techniques.

METHODS

This is a narrative review derived form the clinical and scientific knowledge of the authors together with consideration of selected literature.

RESULTS

Consideration of measured bladder pressure urinary flow rate during voiding in an invasive pressure flow study is considered the gold standard for categorization of bladder outlet obstruction (BOO). The diagnosis is currently made by plotting the detrusor pressure at maximum flow (p(detQmax)) and maximum flow rate (Q(max)) on the nomogram approved by the International Continence Society. This plot will categorize the void as obstructed, equivocal or unobstructed. The invasive and relatively complex nature of this investigation has led to a number of inventive techniques to categorize BOO either by measuring bladder pressure non-invasively or by providing a proxy measure such as bladder weight.

CONCLUSION

Non-invasive methods of diagnosing BOO show great promise and a few have reached the stage of being commercially available. Further studies are however needed to validate the measurement technique and assess their worth in the assessment of men with LUTS.

Executive summary: The International Consultation on Incontinence 2008--Committee on: "Dynamic Testing"; for urinary incontinence and for fecal incontinence. Part 1: Innovations in urodynamic techniques and urodynamic testing for signs and symptoms of urinary incontinence in female patients

AIMS

The members of The International Consultation on Incontinence 2008 (Paris) Committee on Dynamic Testing' provide an executive summary of the chapter 'Dynamic Testing' that discusses (urodynamic) testing methods for patients with signs and or symptoms of urinary incontinence. Testing of patients with signs and or symptoms of faecal incontinence is also discussed.

METHODS

Evidence based and consensus committee report.

RESULTS

The chapter 'Dynamic Testing' is a continuation of previous Consultation-reports added with a new systematic literature search and expert discussion. Conclusions, based on the published evidence and recommendations, based on the integration of evidence with expert experience and discussion are provided separately, for transparency.

CONCLUSION

This first part of a series of three articles summarizes the committees recommendations about the innovations in urodynamic study techniques 'in general', about the test characteristics and normal values of urodynamic studies as well as the assessment of female with signs and or symptoms of incontinence and includes only the most recent and relevant literature references.

Interobserver agreement for noninvasive bladder pressure flow recording with penile cuff

PURPOSE

We assessed variability in interpreting noninvasive measurements of bladder pressure and urine flow between experienced and novice users of the penile cuff.

MATERIALS AND METHODS

Urodynamicists at 6 sites were asked to use the penile cuff test as part of clinical assessment in 30 men presenting with lower urinary tract symptoms. After a short training period they measured maximum flow rate and cuff interruption pressure from penile cuff test recordings to enable categorization of bladder outlet obstruction using a nomogram. Similar measurements were then made on the same traces by 2 expert observers from the originating center. Interobserver differences were assessed.

RESULTS

Complete agreement on obstruction categorization was seen in 77% of subjects, which increased to 86% when plots positioned on category boundary lines were allocated to the favored category. The 95% confidence limits of interobserver variability in maximum flow rate and cuff interruption pressure measurements were +/- 1.7 ml per second and +/- 13 cm H(2)O, respectively, although a small number of studies yielded discrepancies between observers that were larger than expected. They arose from complex recordings but were equally likely between experts as between expert and novice. Investigation of the causes suggested in some cases how such discrepancies may be avoided in the future.

CONCLUSIONS

The excellent level of agreement in measurement and categorization after a short training period suggests that introducing the penile cuff test as part of assessment in men with lower urinary tract symptoms would be straightforward.

A novel intraurethral device diagnostic index to classify bladder outlet obstruction in men with lower urinary tract symptoms

Objectives. Using a urethral device at the fossa navicularis, bladder pressure during voiding can be estimated by a minimal invasive technique. This study purposes a new diagnostic index for patients with lower urinary tract symptoms (LUTSs). Methods. Fifty one patients presenting with LUTSs were submitted to a conventional urodynamic and a minimal invasive study. The results obtained through the urethral device and invasive classic urodynamics were compared. The existing bladder outlet obstruction index (BOOI) equation that classifies men with LUTSs was modified to allow minimal invasive measurement of isovolumetric bladder pressure in place of detrusor pressure at maximum urine flow. Accuracy of the new equation for classifying obstruction was then tested in this group of men. Results. The modified equation identified men with obstruction with a positive predictive value of 68% and a negative predictive value of 70%, with an overall accuracy of 70%. Conclusions. The proposed equation can accurately classify over 70% of men without resorting to invasive pressure flow studies. We must now evaluate the usefulness of this classification for the surgical treatment of men with LUTSs.

Urodynamics: what to do and when is it clinically necessary?

The role of urodynamics in the evaluation and treatment of men with lower urinary tract symptoms is not well defined. Symptoms do not correlate very well with urodynamic findings, but patients with prostatic obstruction fare better after ablative prostatic surgery than those with impaired detrusor contractility. The only proven method for distinguishing between the two is urodynamics, ie, the detrusor pressure/uroflow study. This article reviews urodynamic techniques and the literature pertaining to urodynamics, along with their clinical utility in benign prostatic hyperplasia. The role of urodynamics in clinical practice is discussed as well.

Beneficial effects of testosterone administration on symptoms of the lower urinary tract in men with late-onset hypogonadism: a pilot study

INTRODUCTION

Elderly men are bothered by lower urinary tract complaints designated as lower urinary tract symptoms (LUTS). In epidemiological studies LUTS appears strongly associated with erectile dysfunction, and also with metabolic syndrome. LUTS occurs at an age at which plasma testosterone levels decline, in some men to hypogonadal values. Objectives. This pilot study tested whether testosterone administration to elderly men complaining of LUTS and whose plasma testosterone levels are below normal, might alleviate LUTS.

METHODS

Group 1 (n = 10) received treatment with testosterone gel (50 mg) daily for three months; group 2 (n = 20) received treatment with injections of testosterone undecanoate 1000 mg for 26 weeks.

RESULTS

Upon these interventions, plasma testosterone increased to the normal range. Symptoms of LUTS, measured by the International Prostate Symptoms Score, improved significantly, and also scores of the Aging Males' Symptoms scale and international index of erectile function improved. There were no untoward effects on the prostate over this period of time of the study.

CONCLUSION

Testosterone administration improved symptoms of LUTS in men with late-onset hypogonadism. The mechanism of action is as yet not understood, but it may be connected with or parallel with the effects of testosterone on penile tissues in hypogonadal men, such as on nitric oxide and phosphodiesterase.

Categorization of obstruction using noninvasive pressure flow measurements: sensitivity to change following prostatectomy

PURPOSE

We determined whether categorizing men with lower urinary tract symptoms using a noninvasive pressure flow nomogram is sensitive to change following the removal of obstruction.

MATERIALS AND METHODS

A prospective cohort of men undergoing transurethral prostate resection was recruited, of whom 143 (69%) underwent noninvasive pressure flow study using the penile cuff technique before and 4 months following surgery. Cuff pressure required to interrupt voiding, estimated isovolumetric bladder pressure and maximum flow rate were recorded during a single void. Values were plotted on a nomogram categorizing cases as obstructed (upper left quadrant), not obstructed (lower right quadrant) or diagnosis uncertain (upper right and lower left quadrants). Changes in maximum flow rate, cuff pressure required to interrupt voiding and nomogram position following transurethral prostate resection were then analyzed.

RESULTS

Transurethral prostate resection resulted in an improved flow rate for all diagnostic groups, which was highest for obstructed cases with a mean +/- SD increase of 11 +/- 6 ml second(-1) (p <0.01). Men categorized with obstruction and those placed in the upper right quadrant showed significant decreases in cuff pressure required to interrupt voiding following transurethral prostate resection with a mean decrease of -45 +/- 35 and -48 +/- 32 cm H(2)O, respectively (p <0.01). The number of cases classified as not obstructed increased from 28 (19%) preoperatively to 114 (80%) after transurethral prostate resection.

CONCLUSIONS

Sensitivity to change following the removal of obstruction further validates the usefulness of noninvasive measurement of bladder pressure by the penile cuff test and the categorization of obstruction by the noninvasive nomogram. Decreased isovolumetric bladder pressure following transurethral prostate resection may reflect a return to normal detrusor contraction strength.

Evidence-based guidelines for the management of lower urinary tract symptoms related to uncomplicated benign prostatic hyperplasia in Italy: updated summary

BACKGROUND AND SCOPE

Despite the high prevalence and huge socio-economic impact of benign prostatic hyperplasia (BPH) in Italy, no national guidelines have been produced so far. This is a summary of the first Italian guidelines on the diagnosis and treatment of lower urinary tract symptoms (LUTS) related to uncomplicated BPH, prepared by a multidisciplinary panel under the auspices of the Italian Association of Urologists and introduced in Italy in 2003. An update compiled by the authors is also included.

METHODS

Relevant papers published from 1998 to 2003 (updated to 2006) were identified through a structured literature review and the quality of evidence presented therein was graded according to the Centre for the Evaluation of Effectiveness in Health Administration (CeVEAS) system. Recommendations were based on evidence from the literature, but also on feedback from practitioners and specialists. MAIN FINDINGS/RECOMMENDATIONS: Given the prevalence of BPH, all men aged > or = 50 years of age should be asked about LUTS and informed about disease characteristics and therapeutic options, while sexual function should always be assessed in patients with severe and long-standing LUTS. Initial assessment should include medical history (including drug and co-morbidity history), digital rectal examination, urinalysis, International Prostate Symptom Score-Quality of Life (IPSS-QoL) and a voiding diary, while prostate-specific antigen (PSA) and measurement of prostate volume by suprapubic ultrasonography are indicated in fully informed patients with a life expectancy of > or = 10 years in whom BPH progression could influence treatment choices. QoL considerations should dictate whether to start active treatment. When QoL is not affected by LUTS, watchful waiting is indicated if symptoms are mild, acceptable if they are moderate. When QoL is affected, medical therapy with alpha1-blockers or 5alpha-reductase inhibitors (the latter indicated in patients with increased prostate volume) is appropriate. Combined therapy with alpha1-blockers + 5alpha-reductase inhibitors should only be considered in patients at high risk for progression (prostate volume > 40 mL or PSA > 4 ng/mL), since the incremental cost of combination therapy vs. monotherapy with alpha1-blockers or finasteride is prohibitive. Selection of the type of surgery should be based on the surgeon's experience, the presence of co-morbid conditions and the size of the prostate. Open prostatectomy and transurethral resection of the prostate (TURP) are recommended in patients with acute or chronic retention of urine, and acceptable in obstructed patients with moderate/severe symptoms and worsened QoL. Transurethral incision of the prostate (TUIP) is acceptable when prostate volume is < or = 30 mL. Holmium laser enucleation of the prostate (HoLEP) may be proposed to motivated patients where expert surgeons are available. Transurethral microwave thermotherapy (TUMT) or transurethral needle ablation (TUNA) may be proposed to motivated patients who prefer to avoid surgery and/or do not respond to medical treatment. The possible effects of medical or surgical treatments on sexual function should always be discussed.

CONCLUSIONS

These guidelines are intended to provide a framework for health professionals involved in BPH management in order to facilitate decision-making in all areas and at all levels of healthcare.

Predicting the Outcome of Prostatectomy Using Noninvasive Bladder Pressure and Urine Flow Measurements

OBJECTIVES

To determine whether categorisation of bladder outlet obstruction (BOO) using measurements of bladder pressure and urine flow obtained by a novel noninvasive medical device (the penile cuff test) improves prediction of outcome from endoscopic prostatectomy (TURP).

METHODS

A consecutive cohort of 208 men undergoing TURP following standard assessment in our institution was recruited, and 179 (86%) completed the protocol. Each subject underwent a penile cuff test prior to surgery; outcome was assessed by change in IPSS at 4 mo. The proportion of men with good outcome (>50% reduction in IPSS) was compared according to categorisation by noninvasive bladder pressure and urine flow measurements.

RESULTS

The cuff test was completed by 93% of men with 2% experiencing an adverse event. Men categorised as having BOO by the test (37% of total) had an 87% chance of a good outcome from TURP (p<0.01), whilst of those deemed not obstructed (19% of total) 56% experienced good outcome (p<0.01). For the remaining men not categorised in these two groups, 77% had good outcome, which was identical to the result of the cohort as a whole (77%, p=NS).

CONCLUSIONS

Urodynamic categorisation using measurements obtained by the noninvasive penile cuff test improves prediction of outcome for men with LUTS undergoing TURP. This finding together with the ease and acceptability of the test suggest its suitability for office-based clinical use to assist men and their physicians in the selection for surgical treatment for relief of LUTS.

Primer: using decision analysis to improve clinical decision making in urology

Many clinical decisions in urology involve uncertainty about the course of disease or the effectiveness of treatment. Many decisions also involve trade-offs; for example, an improvement in patient survival at the cost of an increased risk of treatment-related adverse effects. Decision analysis is a formal, quantitative method for systematically comparing the benefits and harms of alternative clinical strategies under circumstances of uncertainty. The basic steps in performing a decision analysis are to define the clinical scenario or problem, identify the clinical strategies to be considered in the decision, enumerate all of the important sequelae of each strategy and their associated probabilities, define the outcome of interest, and assign a value to each possible outcome. Health outcomes can be defined in a number of ways, including quality-adjusted survival. A key aspect of decision analysis is allowing the values of particular health outcomes to vary from patient to patient, depending on individual preferences. Decision analysis has already been used to assess a variety of prevention, screening and treatment decisions in urology, and there is much potential for its future application. Greater incorporation of decision-analytic techniques into urology research and clinical practice might improve decision making, and thereby improve patient outcomes.

Variation in invasive and noninvasive measurements of isovolumetric bladder pressure and categorization of obstruction according to bladder volume

PURPOSE

We developed a noninvasive test that provides an estimate of isovolumetric bladder pressure by measuring the pressure required to interrupt voiding using controlled inflation of a penile cuff. We noted variation in serial measurements obtained during a single void and, therefore, we determined whether this represents variation in detrusor contraction strength, as predicted in previous studies, or measurement error.

MATERIALS AND METHODS

A total of 36 symptomatic men underwent simultaneous invasive and noninvasive pressure flow studies. Corresponding values of isovolumetric bladder pressure and cuff interruption pressure were recorded at each flow interruption and grouped according to bladder volume to calculate measurement error and bias at various points during a void. Individual variation in the 2 measurements across a range of normalized bladder volumes was then examined using ANOVA.

RESULTS

Cuff interruption pressure showed a consistent level of accuracy as an estimate of isovolumetric bladder pressure across a range of volumes. There were similar, statistically significant differences in isovolumetric bladder pressure and cuff interruption pressure recorded at specific volume increments with the highest values seen in the mid range and the lowest seen at lower bladder volumes (each p <0.01). When plotting, the maximum recorded value of cuff interruption pressure in each individual on our proposed noninvasive pressure flow nomogram provided the best diagnostic accuracy for obstruction.

CONCLUSIONS

This study shows that cuff interruption pressure varies in the expected manner with bladder volume and provides a consistent estimate of isovolumetric bladder pressure throughout a void. These data provide important guidance for interpreting noninvasive pressure flow studies and classifying obstruction on the proposed nomogram.