Alfuzosin and postvoid residual urine volume

Clinical bottom line

High postvoid urinary volume was correlated with low maximum urinary flow rate in men with benign prostatic hyperplasia. Alfuzosin reduced postvoid urine volume more than placebo over six months.

Reference

SA McNeill et al. Postvoid residual urine in patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia: pooled analysis of eleven controlled studies with alfuzosin. Urology 2001 57: 459-465.

Study

Individual clinical data on 1470 men in eleven double-blind studies was available. Random allocation between alfuzosin (2.5 mg three times a day or 5 mg twice a day) and placebo took place in 953 of them.

All data was used to establish a relationship at baseline between post void urinary volume (PVR) and maximum urinary flow rate. Only the randomised data was used to establish the effect of alfuzosin.

Results

PVR and urinary flow rate

High postvoid urinary volume was correlated with low maximum urinary flow rate. The percentage of men with a PVR greater than 100 mL was higher in those with a maximum urinary low rate of below 8 mL per second than in those with higher maximum flow rates (Figure 1).

Figure 1: Percentage of men with PVR greater than 100 mL by maximum urinary flow rate

Effect of alfuzosin

Alfuzosin was responsible for a significantly greater fall in PVR over six months than placebo (Figure 2). The effect at six months was no greater than that at three months.

Figure 2: Change in PVR in men taking alfuzosin and placebo

The effect of alfuzosin at six months was greater in men with higher baseline PVR than in those with a lower PVR (Table 1). Acute urinary retention occurred in 2/607 (0.3%) men taking alfuzosin and 5 of 346 (1.4%) taking placebo. Six of the seven men had baseline postvoid urine volumes of more than 100 mL.

Table 1: Effect of alfuzosin according to baseline PVR

Mean fall in postvoid urine volume (mL) at six months, PVR more than
50 mL		100 mL		150 mL
Placebo	Alfuzosin	Placebo	Alfuzosin	Placebo	Alfuzosin
-22.6	-36.8	-42.2	-64.4	-61.4	-109.7

Comment

This is a nice example of what can be done with individual patient data. It also helps to demonstrate those men who are most likely to benefit from alfuzosin, or alpha-blockers generally. Finally it tells us that the full effects of alfuzosin should be apparent by three months, and that little additional benefit is likely thereafter.