PSA, TZI, RI OF PROSTATE AS RISK FACTORS OF URINARY RETENTION

Objective: To evaluate some parameters as the predictors of urine retention incident in Benign Prostate Hyperplasia (BPH) patients. Materials & Methods: From May to August 2012, a total of 24 BPH patients aged 47-69 years with lower urinary tract symptomps (LUTS) including 12 patients with urine retention were participated in the study. Prostate specific antigen (PSA) examination was performed on all patients. For urine retention patients, PSA was performed 2 weeks after catheterization as the procedure may affect PSA levels. Transrectal ultrasonography (TRUS) was examined to assess total prostate volume (VTP), transitional zone volume (VZT), transitional zone index (IZT = VZT / VTP), and resistive index of prostate capsulary arteries. Statistic was utilized using simple and multiple logistic regression. Receiver operating characteristic (ROC) was calculated to assess the usefulness of parameters as a predictor of urine retention. Results: There was no significant difference in age between LUTS and BPH patients with urine retention (p = 0,487). There was no relationship between PSA and transitional zone index to incidence of urine retention in BPH patients (PSA; p = 0,173 and TZI; p = 0,192). Multiple logistic regression analysis showed only resistive index of prostate capsulary arteries which correlates with urine retention incidence (p = 0,014), with area under ROC 0,865 (95% CI 0,721 to 1,008) and cut-off value of > 0,675 as a predictor of urine retention incidence. Conclusion: Resistive index of prostate capsulary arteries by transrectal ultrasonography (TRUS) is a predictor of urine retention incidence in BPH patients.


INTRODUCTION
BPH is a benign enlargement of the prostate, histologically can be found in patients above 41 years of age, causing obstruction of the lumen of the urethra and LUTS and decreasing quality of life in measure prostate volume and prostate transitional zone volume.Transitional zone index was obtained by dividing transitional zone volume with total prostate volume.Five Mhz-Doppler frequency was used with a repetition frequency of 1-3 kHz.After finding of at least 5 pulsatile waveform, peak systolic patients with urine retention.In addition, there are other tests that are non-invasive method to determine the presence of BOO such as PSA, TZI examination and resistive index (RI) of prostate capsulary arteries. 7By finding the level of PSA, TZI, and RI of prostate capsulary arteries, the incidence of urine retention in BPH patients can be predicted.

MATERIALS & METHODS
From May 2012 to August 2012, as many as 60 BPH patients were participated in the study.Among those, 25 patients came with urine retention.Exclusion criteria including bladder stones, prostate and bladder malignancy, urethral stricture, diabetes mellitus, history of previous prostate surgery, and previous medical treatment.PSA examination was performed on all patients.For urine retention patients, PSA was performed 2 weeks after catheterization as the procedure may affect PSA level.

RESULT
Of the 60 patients with BPH, 26 patients were excluded, including 31 patients with age 70 years, 4 patients because of bladder stones, and 1 patient with previous prostate surgery, leaving 12 patients with BPH-LUTS and 12 patients with BPHurine retention.Of 60 BPH patients, the mean age for BPH-LUTS was 59,83 ± 6,65 years and BPH-urine retention 61,58 ± 5,40 years.There were no significant differences between the two groups (p = 0,487) (Table 1).In urine retention patients, examination of PSA was done twice, at thw tim of acute urine retention and 2 weeks after when the catheter was removed.There were significant differences in PSA levels at the time of urine retention with PSA levels 2 weeks after catheter placement (p = 0,024) (Table 2).Table 3 shows PSA levels in BPH-LUTS as well as BPH-urine retention.Simple logistic regression revealed p = 0,173 which means no relationship between PSA levels with the incidence of urine retention.

B OR p
Multiple logistic regression was calculated from the 3 parameters used as predictors of urinary retention incidence and revealed only RI of prostate capsulary arteries associated with the incidence of urinary retention (p = 0,014), whereas PSA levels Resistive index value derived from the prostate using TRUS Doppler examination revealed a mean of 0,64 ± 0,09 and 0,75 ± 0,06 in BPH-LUTS and BPH-urine retention group, respectively.Regression test showed p = 0,014 (table 5). of RI of prostate capsulary arteries as a predictor of urine retention incidence with area under the curve 0,856 (95% CI 0,721 to 1,008) (Figure 1).Cut-off value of this RI is 0,675 with a sensitivity 92%, specificity 67%, positive predictive value 73%, and negative predictive value 89% (Table 7) 1. Specificity zone index value, the greater the possibility of urine retention.Milonas in 2003 found that transitional zone index can be used as a predictor of urine retention incidence with cutoff 0,62.The same study was done by Kurita in 1998 which revealed a cut-off of 0,65 to predict urine retention. 13The difference between our study and previous studies is the restriction of the study subjects age (50-70 years).Another possibility is that prostate volume of Indonesian men is relatively smaller than that of European, but there has not been any study which compares prostate volume of Indonesian men with that of Asian or European.While in one study, prostate volume of Japanese men is smaller than that of American men.

DISCUSSION
The association between PSA levels and increase is the suppression of peripheral zone to prostate capsule, which will be followed by an increase in intraprostatika pressure and RI of prostate capsulary arteries. 4,15Logistic regression test was performed from RI BPH-LUTS and BPH-urine retention groups with results p = 0,014 (OR = 5x107), meaning there is a relationship between RI prostate volume, 8 showed that prostate volume of prostate capsulary arteries with urine retention.
increased with BOO and urine retention, causing PSA levels can be used as a risk factor for urine retention in BPH patients.
2,3,9 It should be noted on PSA examination of urine retention patient that PSA levels may significantly different during AUR and when the catheter was removed, 2 weeks afterward (p = 0,024).It is recommended that PSA should be checked at least 2 weeks after catheterization in urine retention patients to eliminate the influence of AUR, as described earlier by Aliasgari's study. 10Elevated PSA levels mechanisms due to urine retention remains unclear.Assumptions is due to infarction in prostate. 10In this study, PSA levels can not be used as a predictor of urine retention incidence (p = 0,173), in contrast to the study by Milonas (2003)  2 in which the PSA cut-off value is > 3ng/dl, this may be caused by differences in the inclusion criterias and the time of PSA sampling.
Increase of prostate volume in BPH patients due to increase of transitional zone causes compression of peripheral zone, central zone, as well as the urethra which in turn causing BOO.
2, 11 Kaplan in 1995 used urodynamic testing to prove the association between TZI and the incidence of prostate obstruction. 12In this study we found p = 0,192 which means the TZI can not be used as a predictor of the incidence of urine retention, while OR = 132,046 indicates the greater the transitional Therefore, it can be used as a predictor of urine retention incidence in BPH patients, whereas a high value of OR showes that the higher the value of RI, the greater the likelihood of urine retention.In this case, patients with high value of RI has a probability of urine retention 5x107 times compared to normal.Shinbo (2012) conducted a similar study and found mean RI for BPH-LUTS as high as 0,702 ± 0,073 and BPH-urine retention 0,815 ± 0,069, as well as showed significant differences between RI BPH-LUTS and urinary retention ( p 0,001). 4 It should be noted that not all patients with BPH-LUTS or urine retention had RI increase.Medial lobe enlargement without any enlargement of the lateral lobes cause no increase of RI. 16 This is possible because of unique prostate anatomy where there is no compression of prostatic capsulary arteries by two lateral lobe.In this case, intravesical prostatic protrusion (IPP) was used to determine the level of BOO.

CONCLUSION
Resistive index of prostate capsulary arteries correlates with the incidence of urine retention in BPH patients and can be used as a predictor of urine retention incidence.The best cutoff value is 0,675.

Table 1 .
Characteristics of subjects by age.

Table 2 .
PSA characteristics in BPH patients during AUR and after the catheter removal.

Table 3 .
Logistic regression of PSA levels.

Table 4 .
Logistic regression of transitional zone index.

Table 5 .
Logistic regression of RI of prostate capsulary arteries.

Table 6 .
Multiple logistic regression test between PSA levels, TZI, and RI of prostate capsulary arteries.

Table 7 .
Sensitivity, specificity, positive predictive value, and negative predictive value for urine retention at different values of RI.