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McConnell JD, Barry MJ, Bruskewitz RC. Benign Prostatic Hyperplasia: Diagnosis and Treatment. Rockville (MD): Agency for Health Care Policy and Research (AHCPR); 1994 Feb. (AHCPR Clinical Practice Guidelines, No. 8.)

  • This publication is provided for historical reference only and the information may be out of date.

This publication is provided for historical reference only and the information may be out of date.

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Benign Prostatic Hyperplasia: Diagnosis and Treatment.

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8Indirect Treatment Outcomes

The indirect outcomes of peak urinary flowrate (Q[max]) and postvoid residual urine are generally utilized as the primary "objective" determinants of BPH treatment efficacy. All active treatment regimens (alpha blockers, finasteride, balloon dilation, TUIP, TURP, and open surgery) result in an increase in Q[max] and a decrease in PVR. Both Q[max] and PVR respond very little to placebo treatment. The degree of improvement in Q[max] and of reduction in PVR is superior with surgical options. TUIP produces Q[max] and PVR improvements similar to improvements produced by TURP. The relative efficacy of alpha blockers and finasteride cannot be determined without a direct comparison in a randomized trial.

Peak Urinary Flowrate (Q[max])

Q[max] has been used in many studies as an outcome parameter, and 24 of the 51 peer review organizations (PROs) in the United States in 1992 used Q[max] as a criterion for the appropriateness of surgical treatment of BPH. Although Q[max] correlates poorly with actual symptom severity, and although its use to predict natural history or treatment outcome for BPH has been poorly studied, Q[max] has been used as one of the more important "objective" outcome parameters in most modern reports of the efficacy of various treatments.

The mean Q[max] for the entire study population before and after treatment has been reported in many studies covering all treatment modalities. If the pre- and posttreatment mean Q[max] values are synthesized across studies and plotted for the eight treatment modalities (Figure 3), several observations can be made:

  • The mean pretreatment average Q[max] is similar for all treatment modalities and ranges from 7.8 to 9.2 mL/sec. The highest values are reported for finasteride (9.2 mL/sec), placebo (9.1 mL/sec), and watchful waiting (9.0 mL/sec); the lowest, for TUIP and TURP (7.8 mL/sec). This finding suggests some degree of homogeneity among these different patient populations.
  • The absolute increase in the average Q[max] in 1,129 placebo-treated patients (finasteride placebo group not included) is negligible (an increase of 0.6 mL/sec). These data were generated by combining all placebo arms regardless of the corresponding active treatment arm. The 1,129 patients represent a worldwide cross section of patients with BPH selected mainly on the basis of symptoms alone.
  • In 17 patients followed by watchful waiting, the Q[max] increased slightly during followup. However, given this small sample, the natural history of urinary flow changes in untreated men remains to be further defined.
  • The increase in Q[max] with alpha blocker treatment (3.8 mL/sec) is slightly higher than for balloon dilation (3.4 mL/sec). Both increases are clearly less than the changes seen after TUIP, TURP, and open surgery. The 1.5 mL/sec increase in Q[max] seen following 12 months of finasteride therapy was statistically better than results following placebo. Comparisons between alpha blocker treatment and balloon dilation should be made with caution due to differences in study design. The best improvements in Q[max] were after surgical removal of hyperplastic tissue by TURP (increase of 9.8 mL/sec) and after open surgery (increase of 14.4 mL/sec).

Figure 3. Mean pre- and posttreatment Q[max] for various BPH treatment modalities.

Figure

Figure 3. Mean pre- and posttreatment Q[max] for various BPH treatment modalities.

Despite limitations of the data sets -- different numbers of patients for whom flowrate data were reported, different durations of followup, variable placebo run-in intervals, possible differences in study populations -- the improvement in Q[max] is clearly superior for any active intervention over placebo or watchful waiting strategies. The best improvements in Q[max] are achieved by surgical means resulting in net removal of tissue. However, surgery results in urinary flowrates higher than those seen in relatively asymptomatic men. Thus, failure of a therapy to achieve surgical-level improvement in Q[max] should not be overemphasized; smaller benefits may be clinically significant. No significant differences between the surgical options (open, TURP, TUIP) are seen within the limitations of the data. Direct comparisons of balloon dilation and the two types of medical therapy cannot be made due to the small number of patients studied. The Department of Veterans Affairs has initiated a trial comparing terazosin with finasteride as well as the combination of these two medications that should define the relative efficacy of these two approaches.

Postvoid Residual Urine

Postvoid residual urine (PVR) has been used extensively as an outcome parameter in many studies and is also used by 49 of the 51 PROs as an indicator for an "appropriate" TURP. The required documentation of PVR ranges from simply mentioning the presence of any PVR (n = 14) to a residual of >200 mL (n = 1), with the majority of PROs requiring >50 mL or 25 percent of bladder capacity.

For studies reporting changes in PVR, the following observations can be made regarding data summarized in Figure 4 :

  • About one-third of patients treated by placebo (n = 145) experiences a decrease in PVR; another third, no change; and another third, an increase.
  • The same holds true for those following a strategy of watchful waiting (n = 197).
  • A significantly higher proportion of patients experiences a decrease in PVR after active treatment modalities, with very few patients having an increase.

Figure 4. Postvoid residual urine status for various BPH treatment modalities.

Figure

Figure 4. Postvoid residual urine status for various BPH treatment modalities.

However, not all the study populations started at a similar mean PVR (see Figure 5). In fact, the mean pretreatment PVR ranges from 28 mL (open surgery) to 205 mL (TUIP). This variation makes comparisons of outcomes difficult. The mean pretreatment PVR for all active treatment regimens (n = 1,194) was 100 mL, and 87 mL for the placebo treatments (n = 859). PVR data are not available for finasteride therapy.

Figure 5. Mean pre- and posttreatment amount of postvoid residual urine for various BPH treatment modalities.

Figure

Figure 5. Mean pre- and posttreatment amount of postvoid residual urine for various BPH treatment modalities.

After treatment, the mean PVR for the active treatment arms dropped to 51 mL, and it fell to 76 mL for placebo. The absolute drop in PVR was the smallest for the placebo arms, but it varied greatly between the various active treatment modalities. All surgical options except for TUIP reduced PVR to less than 50 mL. The mean PVR after TUIP was still 92 mL. However, the pretreatment PVR was also clearly the highest in this modality (205 mL). One TUIP study of 32 patients reported a pretreatment PVR of 441 mL and a posttreatment PVR of 139 mL. If this study were not considered, the average PVR for TUIP would drop from 205 to 126 mL, and the posttreatment PVR from 92 to 75 mL, making it more comparable to the other active treatment modalities. Therefore, the difference in PVR response seen between TURP and TUIP likely reflects differences in the populations studied, rather than in the treatments.

Despite the different pretreatment PVR volumes, surgical treatment tends to decrease the amount by 60 to 80 percent and alpha blockers reduce it by 50 percent. Placebo treatment has little if any effect on this parameter.

Conclusions

Analyses of the indirect treatment outcomes Q[max] and PVR reveal the following:

  • All active treatments decrease PVR by >50 percent whereas placebo treatment reduces it minimally. With watchful waiting, an increase in PVR can occur.
  • There is a correlation between the increase in Q[max] (percent) and the decrease in PVR (percent) that becomes most evident by comparing the placebo group (no change in either parameter) with all active treatment regimens.
  • Q[max] and PVR data are capable of distinguishing between placebo-treated patients and actively treated patients regardless of the treatment option chosen, the composition of the study population, and the comparability of the pretreatment data.

The number of patients in watchful waiting studies is inadequate to determine the probability of significant PVR increases or Q[max] decreases over time. The short duration of placebo treatment in drug studies precludes any determination of "deterioration" in this group as well. Clearly, any form of active treatment studied has some chance of improving Q[max] and PVR compared with no treatment. Moreover, surgical intervention, whether TURP, TUIP, or open prostatectomy, is superior to alternative therapies with respect to these two indirect outcomes. With regard to PVR, the risk of residual urine, and therefore the benefit of reducing it, has not been defined.

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