Importance of prostate volume and urinary flow rate in prediction of bladder outlet obstruction in men with symptomatic benign prostatic hyperplasia

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1 BPH Importanc of prostat volum and urinary flow rat in prdiction of bladdr outlt obstruction in mn with symptomatic bnign prostatic hyprplasia Darius Trumbckas 1, Daimantas Milonas 1, Mindaugas Jivaltas 1, Aivaras Jonas Matjosaitis 1, Marius Kincius 1, Aivaras Grybas 1, Vytis Kopustinskas 2 1 Clinic of Urology, Lithuanian Univrsity of Halth Scincs, Kaunas, Lithuania 2 Cntr of Statistics, Univrsity of Vytautas Magnus, Kaunas, Lithuania ky words prostat volum» urinary flow rat» bladdr outlt obstruction» bnign prostatic hyprplasia» prssur/flow study Abstract Objctivs. To prdict bladdr outlt obstruction with paramtrs of non-invasiv invstigations for patints with symptomatic bnign prostatic hyprplasia. Patints and mthods. A sampl of 122 mn with modrat to svr lowr urinary tract symptoms suggstiv of bnign prostatic hyprplasia was slctd. Transrctal prostat ultrasound, fr flow masurmnt, and transabdominal ultrasound for rsidual urin wr carrid out togthr with digital rctal xamination for all patints. All patints undrwnt urodynamic prssur/flow tst. Two groups of obstructd (91 patint) and quivocal/unobstructd (31 patint) wr analyd. Probabilistic modl basd on logistic rgrssion was dvlopd for prdiction of obstruction. Rsults. Various paramtrs wr compard in obstructd and non-obstructd/quivocal groups, highlighting important paramtrs for obstruction. Corrlation analysis indicats highr obstruction dpndnc on avrag and pak flow rats and lowr dpndnc on total prostat and transition on volums, transition on indx. Binary logistic rgrssion modl suggsts that avrag flow rat combind with total prostat volum is th bst prdictor of obstruction (83% of corrct prdictions; PPV = 92%; NPV = 52%) in th analyd sampl. Th analyd modl suggsts that pak flow rat could also b almost qually important paramtr instad of avrag flow rat. Conclusions. Th study suggsts that avrag/pak flow rat combind with total prostat volum can b usd for prdiction of obstruction. Th dvlopd probabilistic modl hlps to dtrmin patints who nd invasiv urodynamic tsting for dcision on surgical tratmnt. INTRODUCTION Bnign prostatic nlargmnt (BPE), bladdr outlt obstruction (BOO) and lowr urinary tract symptoms (LUTS) is th basic triad for clinical diagnosis of bnign prostatic hyprplasia (BPH) [1]. BPH is rar in mn youngr than 40, but is prsnt in up to 50% of mn ovr 60 yars of ag and narly 88% by 80 yars of ag [2, 3]. Macroscopic nlargmnt of th gland is found in almost half of mn who hav microscopic BPH. Symptoms causd by BPH and namd LUTS, can b catgorid as obstructiv (voiding) and irritativ (storag). Obstructiv symptoms ar causd by nlargmnt of th physical mass of th gland (static componnt) as wll as ton of smooth muscl of th prostatic stroma (dynamic componnt). Irritativ symptoms ar associatd with th bladdr dysfunction causd by BOO [4]. It has bn stimatd that 25% of mn in thir sixth dcad of lif hav urinary symptoms and objctiv signs of BOO [2]. Howvr, th vidnc for a dirct link btwn BPE, BOO, and LUTS is far from convincing [4, 5]. Th aim of surgical tratmnt for BPH is to rliv or liminat BOO. Most patints with LUTS and an nlargd prostat will bnfit from prostatctomy; howvr, part of thm still xprinc prsistnt storag symptoms [4]. Fiftn to 30% of th patints with BPH do not hav a favorabl outcom aftr transurthral rsction of th prostat (TURP) if symptoms ar considrd [6]. On of th main causs of unfavorabl rsults is absnc of obstruction bfor surgry. Prssur-flow urodynamic studis rmain th most dfinitiv mthod of objctiv documnting BOO. It srvs as th bst instrumnt to find out if th symptoms ar causd by prostatic obstruction or bladdr dysfunction [7]. Proprativ invstigations with prssur-flow study has bn dmonstratd that 20-50% of patints with LUTS had no urodynamic vidnc of obstruction [7-9]. Howvr suitability of urodynamics in assssing BPH is controvrsial in trms of invasivnss, cost, tim consumption, and, both, rproducibility and variability of rsults [7]. Thrfor ths studis still ar not routinly rcommndd in BPH. It has bn provn that th diagnosis of BOO cannot b mad by symptomatic assssmnt alon [8]. Si of prostat and postvoid rsidual (PVR) of urin ar important in valuation of BPH, but not critical for diagnosis of obstruction. It has bn confirmd by studis that th bst singl prdictor of BOO is urinary flow rat. Approximatly 70% of mn with pak flow rat (Qmax) lss than 15 ml/s ar obstructd [10]. Valu of othr paramtrs of fr flow is mor controvrsial. Rcnt studis show that ultrasound stimatd prostat wight or prostat transition on volum can also prdict obstruction [11, 12]. Bttr prdiction of obstruction using paramtrs of noninvasiv invstigations aimd to improv rsults of BPH surgry is an important topic for mor than two dcads, but thr is no worldwid-accptd modl. Som studis show that prdictability of convntional tsts alon or in combination for BOO is only 60-70% [13]. Th aim of our study was to look for possibly bttr simpl prdictors. 75

2 Darius Trumbckas, Daimantas Milonas, Mindaugas Jivaltas, Aivaras Jonas Matjosaitis, Marius Kincius, Aivaras Grybas, Vytis Kopustinskas MATERIAL AND METHODS Thr wr 122 mn agd yars with modrat to svr LUTS suggstiv for BPH involvd in this prospctiv study during th priod from March 2003 to Dcmbr Prmission for th study was obtaind from th Rgional Ethics Committ. Informd consnt was rcivd from all patints. Only subjcts with Intrnational Prostat Symptom Scor (IPSS) 7 and Qmax in rang 3-20 ml/s in total voidd volum of 120 ml or gratr wr includd. Symptoms wr masurd according IPSS togthr with quality of lif (QoL) qustion. All uroflow tracs wr rviwd by a singl invstigator for corrction of artifacts. Individuals who had undrgon prvious prostat or lowr urinary tract surgry or who had prostat cancr or PSA lvl xcding 10 ng/ml wr xcludd. Carcinoma of th prostat in cas of PSA rang 4 to 10 ng/ml had to b xcludd by prostat biopsy. Patints with bladdr stons, urinary tract infction, and suprapubic drainag as wll as vidnc of nurognic bladdr wr xcludd from th study. Uroflowmtric fr urinary flow masurmnt (Urodyn 1000, Mdtronic) was prformd for flow paramtrs. Prostat si was masurd by transrctal ultrasound (Simns Sonolin SI-250 with prob of MH) valuating total prostat volum (TPV) as wll as transition on volum (TZV). For calculation of prostat volum, th llipsoid formula (0.52 x width x hight x lngth) was usd [14]. Transition on indx (TZI) was calculatd by dividing TZV/TPV. Post void rsidual (PVR) was masurd by transabdominal ultrasound using bladdr masurmnts in transvrs and sagittal plains immdiatly aftr fr flow masurmnt. Evntually all patints undrwnt urodynamic prssur-flow study (Dut Logic, Mdtronic, softwar Dut 8.37, Mdtronic Functional Diagnostics Tabl 1. Charactristics of obstructd and unobstructd/quivocal patints A/S). Bladdr filling with subsqunt prssur-flow study was prformd in rat of 30 ml/min with 37 C salin via transurthral two-channl 7 F urodynamic cathtr. Th tst was rpatd two tims and lowr dgr of obstruction showing data was takn to account. Th Intrnational Continnc Socity (ICS) nomogram was usd for obstruction valuation. According to this nomogram th patints wr classifid into two groups: obstructd (Abrams- Griffiths numbr AG >40) and unobstructd/quivocal (AG 40). Comparing to Schafr nomogram ths groups wr sparatd by lin btwn catgoris two and thr. Urodynamic studis wr prformd and valuatd according ICS rcommndations by on invstigator (DT). Statistical analysis was prformd using SPSS softwar. Man, standard dviation (SD),, mdian, and corrlation cofficints (r) wr calculatd. Significant diffrncs in groups wr analyd by t-tst for indpndnt normally distributd sampls and by Mann-Whitny U tst for non-normally distributd sampls. Th binary logistic rgrssion modl was dvlopd for obstruction probability stimation and idntification of th most important prdictors. A lvl of statistical significanc was chosn to b 95%. RESULTS Thr wr 91 obstructd and 31 unobstructd/quivocal out of 122 tstd patints. Ag of patints was not statistically diffrnt btwn th groups (p = 0.088). Qmax in rang of 4-15 ml/s was dtrmind in 85.3% of patints. Th charactristics of paramtrs for both groups ar summarid in Tabl 1. A statistically significant diffrnc btwn th groups was rachd for total IPSS scor, scor of obstructiv symptoms valuatd by qus- Man All patints, n = 122 Obstructd, n = 91 Unobstructd/quivocal, n = 31 SD Mdian Man SD Mdian Man SD mdian Ag (yars) Duration of symptoms (yars) Irritativ symptoms (2,4,7 of IPSS) Obstructiv symptoms (1,3,5,6 of IPSS) p-valus IPSS QoL PSA (ng/ml) Post void rsidual (ml) Total prostat volum (ml) Transition on volum (ml) TZI Qmax fr (ml/s) Qav fr (ml/s) AG numbr pdtqmax (cm/h 2 O) IPSS Intrnational Prostat Symptom Scor, QoL Quality of Lif scor, TZI transition on indx (transition on volum/total prostat volum), Qmax fr fr pak flow rat, Qav fr fr avrag flow rat, AG numbr obstruction numbr, if ovr 40 obstruction (AG numbr = pdtqmax 2 Qmax), pdtqmax dtrusor prssur at pak flow). p - valus wr calculatd to tst significant diffrncs btwn th groups (diffrnc considrd statistically significant if p <0.05), SD standard dviation. 76

3 Importanc of prostat volum and urinary flow rat in prdiction of bladdr outlt obstruction in mn with symptomatic bnign prostatic hyprplasia tions 1, 3, 5, and 7 of IPSS, TPV, TZV, TZI, pak (Qmax) and avrag (Qav) flow rats, as wll as PVR. Ths variabls corrlatd with th dgr of obstruction valuatd by th AG numbr, but high corrlation was obsrvd only with Qav and Qmax (r rspctivly and , p = ). AG numbr corrlatd with TZI (r = 0.29, p = 0.001), total prostat and transition on volums (r = 0.27 for both, p = 0.003) as wll. Corrlation with rsidual urin was considrably lowr (r = 0.198, p = 0.03). No statistically significant corrlation btwn ag of patints and obstruction was obsrvd. Logistic rgrssion modl suggsts that obstruction is bst prdictd whn combination of Qav and TPV ar usd. Ovrall prognostic powr of this combination for dtcting corrct rsults was 83% (with probability cut valu of 0.6). PPV (positiv prdictiv valu) = 92%; NPV (ngativ prdictiv valu) = 52%. Prognostic powr for prdiction of obstruction in th first group rachd 91%. Unobstructd/quivocal subjcts wr prdictd corrctly in 61% of cass in th scond group. Analysis of odds ratio (OR) for ach variabl shows that in cas of Qav and TPV it was rspctivly 0.61 (95% CI ) and 1.04 (95% CI ). It mans that incras of Qav by 1 ml/s dcrass obstruction probability by 1.6 tims and incras of total prostat volum by 1 ml incrass it by Th dvlopd binary logistic modl for prdiction of obstruction is th following: P =, 1 + whr P probability of obstruction; = TPV Qav It can b calculatd that in cas of total prostat volum 40 ml and Qav 5 ml/s probability of obstruction quals to 0.75 (75%). Prdictiv powr of Qmax in combination with TPV was slightly lowr small diffrnc is sn only in th group of unobstructd/quivocal subjcts (58% of corrct prdictions) with th almost sam rat of corrct rsults in total and in th group with obstruction. Compatibility of modl with th data (Cox Snll and Naglkrk cofficints of dtrmination) was slightly lowr in cas of Qmax and TPV. Equation for prdiction of obstruction with Qmax in combination with TPV is th following: P =, 1 + whr = TPV Qmax Combinations of TZV or TZI with Qmax or Qav wr not suprior in prdiction of obstruction compard to TPV. Th fr flow pattrn of a patint with TPV of 51 ml (Fig. 1) and computr basd calculation of obstruction probabilitis (Fig. 2) ar prsntd. Changs in obstruction probability du to valu of paramtrs ar shown in Figs. 3 and 4. Fig. 3 visualis obstruction probability as function of avrag flow rat and TPV. Figur 4 prsnts isolins of slctd obstruction probability. Figur 4 also Variabls TPV (cc) 51 Qav (ml/s) 10 Qmax (ml/s) 18.4 Intrmdiat calculations Probability of obstruction according Qav 0.27 Probability of obstruction according Qmax 0.35 Fig. 2. Obstruction prdictd for th sam 59-yar-old patint. Total prostat volum 51 ml, pak flow rat 18.4 ml/s, avrag flow rat 10 ml/s. Probability of obstruction 27-35%. Fig. 3. Bladdr outlt obstruction probability dpndnc on total prostat volum (TPV) and avrag flow rat (Qav). Fig. 4. Bladdr outlt obstruction probability isolins du to total prostat volum (TPV) and avrag flow rat (Qav). visualis th ara of obstruction probability bing mor than 0.9 isolin (uppr lft cornr of th plot). DISCUSSION Fig. 1. Uroflowmtric trac of a 59-yar-old patint with total prostat volum of 51 ml: pak flow rat 18.4 ml/s, avrag flow rat 10 ml/s. In fac of numrous micro-invasiv tchniqus for BPH tratmnt, transurthral rsction is still th main and th bst option. TURP is prformd in approximatly 95% of surgical procdurs and opn procdurs ar rsrvd only for vry larg prostats [15]. 77

4 Darius Trumbckas, Daimantas Milonas, Mindaugas Jivaltas, Aivaras Jonas Matjosaitis, Marius Kincius, Aivaras Grybas, Vytis Kopustinskas Tabl 2. Approximat probabilitis of bladdr outlt obstruction Total prostat volum (ml) Qav (ml/s) * * 0.78* * 0.68* 0.75* * 0.56* 0.65* 0.73* 0.8* * 0.53* 0.62* 0.7* 0.77* * 0.5* 0.59* 0.68* 0.75* * 0.56* 0.65* 0.73* 0.79* * 0.52* 0.62* 0.7* *suggstd indication for prssur/flow study; Qav avrag flow rat In th Dpartmnt of Urology at Kaunas Mdical Univrsity Hospital, prostatctomis du to BPH ar prformd annually, TURP compris 60-70%. Though TURP is an ffctiv procdur with good or xcllnt rsults in 80-85% of cass [6, 16, 17], th possibility of an unfavorabl outcom is still high. On of rasons for unfavorabl rsults is unsatisfactory proprativ slction of patints. Prdiction of obstruction in trms of postoprativ ffct would b of most important valu. According to litratur, th most valuabl paramtr for prdiction of obstruction is pak flow rat (Qmax). In cas of Qmax <10 ml/s, liklihood of obstruction is 90%, in rang of Qmax ml/s 67% and in Qmax >15 ml/s only 30% [15]. Approximatly 1/3 of patints with Qmax ovr 10 ml/s ar unobstructd. Probability of obstruction in cas of Qmax >10 ml/s for ldrly man (>80 yars) falls to 40% [15]. In som studis, on th basis of uroflow alon, 21% of th patints wr misclassifid [6]. Singl or combind convntional tsts can prdict corrctly just in 60-70% of cass [13]. According to our study, misclassifications in 21-25% is possibl if only a singl fr flow paramtr, Qmax or Qav, is usd. Tracs of uroflow oftn hav paks and rgistrd Qmax is not rliabl. Such artifacts nd to b corrctd. Avrag flow rat is a quit stady paramtr and should b important in cas of continuous flow without trminal dribbling [3]. Our study shows, that Qav prdictd obstruction vn bttr than Qmax, but th diffrnc compar to Qmax was not pronouncd. Combination of Qav and TPV had th bst prdictiv powr in our sampl. Combinations of Qmax TPV or Qmax TZV wr not suprior. As has bn shown in many of studis PVR is not important prdictor of obstruction. Our data also confirm that post-void rsidual volum is not of paramount importanc in trms of obstruction. Though w found statistically significant diffrnc for PVR btwn th groups, corrlation of PVR with obstruction was wak. Prdictiv modls usually us PVR as on of important paramtrs (Clinical Prostat scor modl dvlopd by Rosir t al. as wll as modls dvlopd by Van Vnrooij t al. and Madrsbachr S. t al.), but w did not find its importanc for prdiction [8]. A big volum of rsidual urin indicats bad dtrusor contractility rathr than obstruction [10]. From th othr hand, bad contractility shows trminal phas of obstructiv procss. Transition on volum mor than total prostat volum rprsnts procsss of bnign hyprplasia. Thrfor, masurmnt of transition on volum is ssntial, spcially in trms of tratmnt options [12]. Transition on volum corrlats wll with rsctd volum of th prostat [12]. It was shown by studis of Kaplan that transition on volum is dirctly associatd with urodynamic obstruction of th bladdr and this corrlation is mostly rliabl whn transition on indx is ovr 0.5 [11]. Though it was shown that transition on indx is important on prdiction of outcom aftr TURP [17], rcnt study did not confirm supriority of TZV or TZI for prdiction of urodynamic obstruction compar to TPV. Thr ar lss corrct prdictors in th group of unobstructd/ quivocal subjcts, which dirctly worsns total rat of corrct prdictions. Bttr prdiction in this group would b vry important bcaus it would lt us improv surgical rsults. Unfortunatly thr ar no clar paramtrs for prdiction of bad contractility/ unobstructd. W guss that in cas of calculatd probability of obstruction , an invasiv urodynamic prssur/flow study would b bnficial, spcially if surgical tratmnt is considrd (Tabl 2). Though combination of Qmax and TPV was not suprior, th prdictiv powr of it was almost th sam as Qav combind with TPV. Considring flow pattrn ithr Qav or Qmax should b usd. Probabilitis should b calculatd using both modls and rsults compard. W suppos that similar rsults show rliabl prognosis. In cas of diffrnc, uroflowmtry should b rpatd and probabilitis r-valuatd. Pronouncd diffrnc and/or probability around 0.5 would b indicativ for invasiv prssur flow study. In cas of high probability of obstruction, urodynamic prssur flow study could b spard. Our study shows that Qav is as good as Qmax and can b usd mor oftn. CONCLUSIONS A binary logistic rgrssion modl was dvlopd, which suggsts that avrag flow rat and total prostat volum ar th bst prdictors of obstruction (83% of corrct prdictions; PPV = 92%; NPV = 52%) in th analyd sampl. Th analyd modl suggsts that pak flow rat could also b an almost qually important paramtr instad of avrag flow rat. Th abov paramtrs could b obtaind from simpl ultrasound and fr flow masurmnts. Th dvlopd probabilistic modl also provids information that is usful to slct patints who nd invasiv urodynamic tsting for dcision on surgical tratmnt. It is suggstd to prform invasiv urodynamic tsting in cas obstruction probability is in th rang of REFERENCES 1. Psc F, Rubilotta E, Rightti R t al: Rsults in 522 patints assssd in a flow-clinic. Urodinamica 2002; 12:

5 Importanc of prostat volum and urinary flow rat in prdiction of bladdr outlt obstruction in mn with symptomatic bnign prostatic hyprplasia 2. Lpor H, Low FC: Evaluation and nonsurgical managmnt of bnign prostatic hyprplasia. In: Walsh PC, Rtik AB, Vaughan ED, Win AJ, ds, Campbll s Urology CD-ROM, 8 dn, Vol. 2. Chapt 39. Philadlphia: Saundrs, Chapl CR, MacDiarmid SA. Voiding difficulty. In: Chapl C, MacDiarmid S, ds, Urodynamics. Mad asy, 2 dn, Vol. 1. Chapt 4. London: WB Saundrs, Harcourt Publishrs Limitd 2000, pp Andrsson KE: Storag and voiding symptoms: pathophysiologic aspcts. Urology 2003; 62 (5 Suppl. 2): Shapiro E, Lpor H: Pathophysiology of clinical bnign prostatic hyprplasia. Urol Clin North Am 1995; 22 (2): Rollma HJ, Van Mastrigt R: Improvd indication and follow-up in transurthral rsction of th prostat using th computr program CLIM: a prospctiv study. J Urol 1992; 148 (1): T AE, Kaplan SA: Urodynamics and bnign prostatic hyprplasia. In: Kirby R, McConnll J, Fitpatrick J, Rohrborn C, Boyl P, ds, Txtbook of Bnign Prostatic Hyprplasia Vol. 1. Oxford: Isis Mdical Mdia LTD 1996, pp Madrsbachr S, Klinglr HC, Djavan B t al: Is obstruction prdictabl by clinical valuation in patints with lowr urinary tract symptoms? Br J Urol 1997; 80 (1): Rodrigus P, Lucon AM, Frir GC, Arap S: Urodynamic prssur flow studis can prdict th clinical outcom aftr transurthral prostatic rsction. J Urol 2001; 165 (2): Jpsn JV, Bruskwit RC: Comprhnsiv patint valuation for bnign prostatic hyprplasia. Urology 1998; 51 (Suppl. 4A): Kaplan SA, T AE, Prsslr LB, Olsson CA: Transition on indx as a mthod of assssing bnign prostatic hyprplasia: corrlation with symptoms, urin flow and dtrusor prssur. J Urol 1995; 154 (5): Milonas D, Trumbckas D, Juska P: Th importanc of prostatic masuring by transrctal ultrasound in surgical managmnt of patints with clinically bnign prostatic hyprplasia. Mdicina (Kaunas) 2003; 39 (9): Homma Y, Gotoh M, Taki M, Kawab K, Yamaguchi T: Prdictability of convntional tsts for th assssmnt of bladdr outlt obstruction in bnign prostatic hyprplasia. Int J Urol 1998; 5 (1): Proto WG: Protocols for th valuation of thrapis in BPO. Othr assssmnts: prostat si and prostat spcific antign. Br J Urol 2000; 85 (Suppl 1): d la Rostt JJ, Prachino M, Thomas D t al: Guidlins on Bnign Prostatic Hyprplasia. Europan Association of Urology / Confrnc Procding 2001: Milonas D: Th influnc of clinical factors on th outcom of surgical tratmnt of bnign prostatic hyprplasia. Thsis/Dissrtation, Kaunas Univrsity of Mdicin, 2004: Milonas D, Jivaltas M, Trumbckas D: Transition on indx th most important proprativ paramtr on prdiction outcom aftr transurthral rsction of th prostat. Eur Urol Suppl 2005; 4 (3): Corrspondnc Darius Trumbckas Clinic of Urology Hospital of Lithuanian Univrsity of Halth Scins Kaunas Clinics Eivniu 2 LT-50009, Kaunas, Lithuania phon: trumbckas@gmail.com 79