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Finasteride: new systematic review

 

Clinical bottom line

Finasteride 5 mg once daily improved symptoms of benign prostatic hyperplasia, increased maximum urinary flow rate, reduced prostatic volume, prevented retention and surgery, at the cost of small levels of harm to sexual function. Maximum benefits were not seen until 12 months of treatment. Finasteride improved maximal flow rate for all sizes of prostate.


Reference

JE Edwards, RA Moore. Finasteride in the treatment of clinical benign prostatic hyperplasia: a systematic review of randomised trials. BMC Urology 2002 2: 14 (http://www.biomedcentral.com/1471-2490/2/14)


Systematic review

The Cochrane Library and PubMed were searched (to April 2001) for full journal publications of trials involving finasteride in the treatment of benign prostatic hyperplasia. Trials had to be both randomised and double-blind, active- or placebo-controlled, and have a variety of outcomes, including measures of efficacy and harm. Duplicate reports of the same study and open-label extensions were excluded.

Sensitivity analyses were for differing severity of symptoms at baseline, different prostate volume at baseline, for results of a dominant trial, and men with previous interventions.

Results

There were 14,700 men in 19 placebo controlled trials, and about 1,600 men in active controlled trials. Individual trials were from 36 to over 3,000 randomised men. Finasteride was mostly used at 5 mg a day, with duration of three to 48 months. Symptoms were moderate to severe at baseline. Trial quality was 3-5/5 on a commonly-used scoring symptoms, implying minimal chance of bias.

Symptom score

Eleven of 14 trials with data showed finasteride to be better than placebo, eight at the p<0.01 level. A subset of the data with the AUA scores are shown in Figure 1. Symptom scores fell (improved) with finasteride and placebo, but the reduction levelled off after 12 months with placebo, but continued to fall with finasteride.

Figure 1: AUA symptom score


Maximum urinary flow rate

Ten of 13 trials with data showed finasteride to be better than placebo, six at the p<0.01 level. Figure 2 shows the weighted mean maximum urinary flow rates, which continued to improve with finasteride up to about three years. The improvement in urinary flow rate with finasteride over baseline was seen any prostate volume.

Figure 2: Maximum urinary flow rate


Prostate volume

Twelve of 15 trials with data showed finasteride to be better than placebo, eleven at the p<0.01 level. Results over 24 months showed that prostate volume continued to fall with finasteride over that period (Figure 3).

Figure 3: Prostate volume


Discontinuations

Overall discontinuations were lower with finasteride than with placebo at 12 months (13% discontinued) and at 48 months (34% discontinued) than with placebo.

Acute retention and surgery

Acute urinary retention occurred less frequently with finasteride than with placebo at 24 and 48 months (Figure 4). The NNT to prevent an episode of acute retention over 48 months was 26 (19 to 44).

Figure 4: Acute retention


BPH-related surgery occurred less frequently with finasteride than with placebo at 24 and 48 months (Figure 4). The NNT to prevent surgery over 48 months was 18 (14 to 27).

Figure 5: BPH-related surgery


Specific adverse events

Table 1 shows the percentage of men affected at 12 months, with NNH values.

Table 1: specific adverse events

Adverse event

Finasteride %

Placebo %

NNH (95%CI)

Serious adverse event

12

13

not calculated

Any sexual dysfunction

14

7

14 (10 to 22)

Decreased libido

5

3

47 (35 to 74)

Impotence

8

3

24 (20 to 31)

Ejaculation disorder

2

1

55 (43 to 74)

Prostate cancer

Prostate cancer rates were the same for finasteride and placebo, occurring in about 1 in 200 men.

Comment

The review is a pretty comprehensive outline of what can be expected in terms of finasteride treatment of men with benign prostatic hyperplasia. There is some down side in sexually-related adverse effects, but as well as relieving symptoms and improving maximum flow rate, it also diminished the incidence of acute retention and BPH-related surgery.

One take-home message about finasteride is that maximum benefits are only seen after 12 months, as the change from baseline symptom reduction calculation shows (Figure 6). The other take home message is that we don't know what change in symptom severity or improvement in maximum flow rate is acceptable to men.

Figure 6: Change in symptom score over baseline