Abstract: Nine randomised clinical trials were included in this review. Eight trials compared alpha blockers versus placebo (five trials tested alfuzosin and two trials tested tamsulosin, one trial tested both alfuzosin and tamsulosin, one trial tested silodosin) and one trial compared an alpha blocker (doxazosin) versus no treatment. Trial without catheter was performed after treatment with the drug for one to three days in seven trials and for eight and 32 days in two other trials respectively. There was moderate quality evidence to suggest that the rate of successful trial without catheter favoured alpha blockers over placebo ( 366/608, 60.2%, of men using an alpha blocker were able to void spontaneously after catheter removal compared with 185/486, 38.1%, using placebo, risk ratio (RR) 1.55, 95% confidence interval (CI) 1.36 to 1.76). The incidence of recurrent acute urinary retention was lower in groups treated with an alpha blocker (RR 0.69, 95% CI 0.60 to 0.79). This evidence was of moderate quality and was statistically significant for alfuzosin, tamsulosin and silodosin, though not for doxazosin. Of the trials mentioning adverse effects (for example, postural hypotension, dizziness), there was not enough information to detect statistically significant differences between the groups (RR 1.19, 95% CI 0.75 to 1.89) and the evidence was of low quality. Overall, adverse effect rates were low for both placebo and alpha blockers and, for example, vasodilatation-related adverse effects did not often result in discontinuation. However, the data in this review are limited due to the large amount of unpublished data that was not available to us. There was some evidence to suggest that alpha blockers increase the success rates of trial without catheter, and the incidence of adverse effects was low. There was some evidence of a decreased incidence of acute urinary retention. The need for further surgery, cost effectiveness and recommended duration of alpha blocker treatment after successful trial without catheter remain unknown as these were not reported by any trial. There is a lack of internationally agreed outcome measures for what constitutes successful trial without catheter. This makes meta-analysis difficult. Large, well-designed controlled trials, which use the recommendations set out in the CONSORT statement, and include clinically important outcome measures, are required.

Plain-language summary: In nine clinical trials men were either given a dummy tablet (placebo, inactive drug), an alpha blocker for one to three days (in one study up to a maximum of eight days and in another for 32 days) or no treatment before the catheter was removed. In ideal circumstances, neither patients nor doctors knew which type of tablet was given, to prevent the bias in reporting the results. The results suggested that alpha blocker treatment increased the chances of successful catheter removal and return to urination although the overall scientific evidence available to support this was limited. Four different alpha blockers were tested (alfuzosin, tamsulosin, doxazosin and silodosin). Their results were similar except for doxazosin which did not seem to make a significant difference. Side effects caused by alpha blockers were few and comparable to placebo or no treatment, though this evidence was limited. They included retrograde ejaculation, dizziness, low blood pressure, fainting, sleepiness, feeling unwell and headache. There was some evidence to say that alpha blockers also reduce the risk of suffering another (recurrent) episode of urinary retention after successful catheter removal, though it remains unclear whether they reduce the need for future surgery on the prostate. It is therefore unclear whether, or for how long, alpha blocker treatment should be continued after successful catheter removal and whether the costs of alpha blocker treatment in such situations are justified. Further research is needed to answer these questions.