Hypothesis / aims of study
Urodynamic grading of bladder outflow obstruction for elderly male with prostate enlargement is (ICS) standardized since 1997.(1) A clinical disease specific nomogram is available to graphically display the pressure flow relation.(2) This nomogram has been the basis for the ICS bladder outflow obstruction index (BOOI) and the ICS bladder contraction index (BCI). Elderly men with symptoms of lower urinary tract dysfunction (LUTS) have a significant chance that bladder outflow obstruction (BOO) is the cause. The growing prostate creates a slowly increasing resistance to the outflow tract, however the resistance is not exactly proportional to the size of the prostate. On the other hand, a reduced flowrate may be caused by an underactive detrusor contraction. Both, flowrate (including PVR) and prostate size have an intermediate sensitivity and specificity with regard to the gold standard diagnosis. Guidelines support the management of LUTS on the basis of subjective expression and interpretation of symptoms plus flowrate maximum. Urodynamic testing is avoided in practice for many reasons and therefore maximum free flowrate is commonly used as the predominant (or only) objective test to grade the dysfunction responsible for the symptoms. We have therefore precisely studied flowrate in comparison with pressure flow outcome and have explored the consequences of diagnosis, on the basis of flowrate, or on urodynamics in nearly 2500 men.
Study design, materials and methods
We analysed 2459 men >45 year with LUTS. All these -consecutive- patients were referred and had bothering symptoms. Urodynamic pressure flow test was done after ICS standard cystometry and in the patients preferred position. We have not excluded measurements, but patients without free flow before urodynamics were not included. Pressure flow result is shown per linearized passive urethral resistance class (LinPURR) and per nomogram contraction class. Free flow study was produced by all included patients just before the cystometry. Not always representative (as reported by the patient), nevertheless all results (with volume over 50mL) were included, to present the most naturalistic set of patients.
The graphs show (upper left) that for the total group of patients absence of BOO (combining OBS grade 0 1 and 2, vertical) with reduced contractility (combining very weak and weak contraction classes) was present in 37.7% of patients. In 34% of all patients contraction was normal or strong, without BOO (< OBS 3). BOO was confirmed in 28.7% of all these men combined with weak contractility in 4.7%. BOO was severe (grade OBS 5 or 6) in 3.3% of the patients. If flowrate was <10mL/s (in 457 men), again, 38.7% of men had no BOO and weak contraction, and 22% of these men had no BOO and normal contraction. 39.2% of these men had BOO; 5.8% in combination with weak contraction and for 6.8% the BOO was graded severe. In the group with flowrate >14mL/s (338 men) only 3 had severe grade of BOO (1%) and 85.6% of these men had no BOO and 56.2% had normal contractility.
Interpretation of results
Flowrate is reduced in patients with BOO. Patients with a flowrate above 14mL/s rarely (14.4%) have BOO, which is virtually never high graded (1%). If the flowrate is <14mL/s roughly 35% of the patients has BOO and underactive detrusor. Of all patients with symptoms and flowrate 28,7% has BOO grade 3 or higher. If BOO grade >3 is taken as the threshold to advise surgical des-obstruction, only 3,3% of all patients would be advised positive for this. 71% of all patients would profit from conservative measures (with low intensity follow up) because no BOO is responsible for their symptoms, however >50% of these men without BOO has underactive detrusor, for whom no specific treatment is available. A proportion of men will have storage dysfunction (uncovered by the urodynamic testing), this is however not included in this analysis (that mimics the usual guideline practice advise). 25,5% of all men could safely continue, or start with specific medical treatment based on a moderate grade of BOO.
Conservative or medical management is usually safe and effective in elderly men with LUTD. However many men want reconfirmation of this when the treatment has been based on symptoms only (has been given ex-juvantibus). They persist anxiety and bother about their symptoms and ask for referral. Objective urodynamic stratification is the golden standard tool to diagnose the dysfunction and urologists are able to use this. ICS has been instrumental to develop the tools and techniques. As stated above: Many men can be reassured and may continue with conservative measures of medication on the basis of urodynamic grading of the dysfunction. Guidelines advise to consider des-obstruction for patients with persisting symptoms and reduced flowrate on the basis of indirect evidence, urodynamics would confirm this individually in around 30% of patients based on an objective measure.