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Viagra for erectile dysfunction

 

Clinical bottom line

Sildenafil (Viagra) is effective for treating erectile dysfunction. With the usual practice of dose optimisation, at least 60% of attempts at sexual intercourse were successful. For global improvement in erections the NNt was 1.7 (1.6 to 1.9). Treatment-relateed adverse effects occurred in 30% of men on sildenafil and 11% on placebo.


Systematic review

Three systematic reviews have been published in 2002. Two have used both published and unpublished information, but have chosen an analysis in which all doses of sildenafil have been aggregated. The third uses clinical trial reports available at the time of licensing in the UK (basically the same clinical trial material), but with an analysis accoring to dose, which makes more sense to us. We have therefore used the paper by Moore et al below, which has the bonus of being freely available on the Internet in BioMed Central.

Viagra dosing usually starts at 50 mg, with the option to increase to 100 mg if effects are less than hoped and with no adverse effects, or to drop the dose to 25 mg if effects are adequate and there are adverse effects. This is called dose optimisation.

RA Moore, JE Edwards, HJ McQuay. Sildenafil (Viagra) for male erectile dysfunction: a meta-analysis of clinical trial reports. BMC Urology 2002 2:6. ( http://www.biomedcentral.com/1471-2490/2/6/ ).

See also:

A Burls, L Gold, IR Rutks, W Clark: Systematic review of randomized controlled trials of sildenafil (Viagra®) in the treatment of male erectile dysfunction. Br J Gen Pract 2001 51: 1004-1012.


HA Fink, R Mac Donald , IR Rutks, DB Nelson, TJ Wilt. Sildenafil for male erectile dysfunction: a systematic review and meta-analysis. Arch Intern Med. 2002 Jun 24;162(12):1349-60.


Review

No searching was required because clinical trial reports were being used. For the review, a prior definition of efficacy was a man with a consistent three-part outcome, consisting of an erection, sufficiently rigid for penetration, and followed by successful intercourse. Other efficacy outcomes of interest were the number of men with the highest two responses on the International Index of Erectile Function (IIEF) questions 3 and 4, and global evaluations of treatment efficacy by patients [9]. The number of grade 3 or 4 erections (at least hard enough for penetration) and successful erections were also noted.


Adverse events were also sought. These were the number of men with any treatment-related adverse event, the total number of men discontinuing, those discontinuing through lack of efficacy or through adverse events, adverse events rated severe or serious, and information on particular adverse events.

Outcomes actually available and chosen were:

Efficacy:

Erections:

Results

Ten of 27 clinical trial reports had relevant information, with 1846 men given sildenafil (25 to 100 mg) and 1131 given placebo. For the efficacy outcomes, dose optimisation produced similar results to those from high fixed doses (Figure 1).

Figure 1: Mean percentage of men achieving the efficacy outcomes


At least 60% of attempts at sexual intercourse successful

For the standard dose optimised regimen, the number needed to treat compared with placebo was 2.7 (2.3 to 3.3)

At least 40% of attempts at sexual intercourse successful

For the standard dose optimised regimen, the number needed to treat compared with placebo was 2.4 (2.1 to 2.9). The outcome occurred in 60% of men on dose optimised sildenafil and 19% on placebo.

Positive response to global question about improved erections

For the standard dose optimised regimen, the number needed to treat compared with placebo was 1.7 (1.6 to 1.9). The outcome occurred in 79% of men on dose optimised sildenafil and 21% on placebo.

Successful erections

The mean number of erections a week and the number of erections resulting in successful intercourse was higher with dose optimised sildenafil than with placebo, or with fixed doses (Figure 2).

Figure 2: Mean number of erections a week and the number of erections resulting in successful intercourse


Adverse effects

Dose optimisation produced the lowest rate of adverse effects, with the rate of serious or severe adverse effects, of discontinuations because of adverse effects, no different from placebo. Overall discontinuations and discontinuations because of lack of efficacy were lower with sildenafil than with placebo. Dyspepsia. vasoldilation and headache occurred more frequently with sildenafil than with placebo.

Comment

More good evidence about sildenafil. It is a shame that a review was not available when sildenafil first became commercially available. It is clear from the review of clinical trial reports that such a review could have done.

Examination of the three reviews will also be interesting and useful for students of evidence-based medicine, and how it is used and put into practice. A "compare and contrast" essay question from these three would make interesting reading.