Epididymectomy is an effective treatment for scrotal pain after vasectomy

Epididymectomy is an effective treatment for scrotal painafter vasectomy. (2000). BJU International, (85), 1097–1099.

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~~I was more interested in the occurance rates for PVPS. 560 patients. 17 came back for denervation. That’s still 3% of patients.~~

Made a mistake here. I used notes from Ahmed 1997 by accident.

Still – there are very serious problems with this study.

This study looks at 16 men who undergo epididymectomy to solve post-operative vasectomy pain. The small sample size causes has significant problems with respect to how seriously you should take this.

14/16 patients with success means that the mean is 0.875.

Computing the sample standard deviation, we get :

s^2 = (14(1-0.875)^2) + 2(0-0.875)^2) / (16-1)

s^2 = 0.116666

s = 0.3415

To get a 95% confidence interval, we do a look up on a t-table. N=16 means we have 15 degrees of freedom. 15 degrees of freedom with two tails gives us a value of 2.131.

So 2.131 standard deviations will give us a 95% CI.

Approximating the standard deviation is s/sqrt(N) which gives us:

approx std deviation = s/sqrt(N)

approx std deviation = 0.3415/sqrt(16)

approx std deviation = 0.08539

So the confidence interval is 2.131 * approx std deviation which gives:

CI = 2.131 * 0.08539

CI = 0.181

So we can say that we can be 95% confident that epididymectomy is effective for somewhere between 69.5% (87.5% – 18.1%) up to 100% (87.5% + 18.1%) of patients.

Let’s be clear – this means the math says that anywhere between 69.5% or 100% are valid numbers for success. That’s a 30% spread – and that’s also because you can’t go more than 100%.

I’m not willing to put my trust in this surgery with these kinds of results.

If you look at newer research, the emperical for epididymectomy looks even worse as it shows that epididymectomy gives only a 55% success rate.

http://lib.bioinfo.pl/pmid:18380787

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