ACUTE RENAL COLIC: WHAT IS THE ROLE OF α-BLOCKERS?
Kay Thomas, Consultant Urological Surgeon, Department of Urology, 1st Floor Thomas Guy House, Guy’s Hospital, London SE1 9RT, UK.
The current management of acute renal colic is usually based on the site and size of stone, adequacy of pain relief and signs of infection. Most patients in the UK are treated conservatively with imaging, analgesia and early clinical follow-up. Only those with a solitary kidney, unremitting pain, sepsis or a large stone with high-grade obstruction are admitted for treatment. The spontaneous stone passage rate depends on stone size and position. Stones of <5 mm have a 98% chance of passing spontaneously, which reduces considerably with stones of >5 mm, whilst stones in the distal ureter are more likely to pass than those more proximally located (70% distal, 45% mid, 25% upper) .
In the last few years, there has been increasing interest in the role of α-blockers in acute renal colic. From animal and human studies α1-adrenergic receptors have been identified in the distal ureter and vesico-ureteric junction. α-blockers are thought to act via these receptors to inhibit basal tone, reduce peristaltic activity and weaken contractions in the ureter. This combination of effects is thought to promote stone passage, increase expulsion rate, and decrease analgesia requirements and hospital attendance rates due to renal colic.
α-blockers have been compared with other agents and against each other in patients with acute renal colic [2–9]. There have been six randomized trials comparing the use of α-blockers alone with standard treatment (Table 1) [4–9]. There are other studies that have shown a benefit when α-blockers are used in addition to steroids  but it is desirable that there is one agent with minimal side-effects but good efficacy (i.e. an α-blocker), which avoids the potential serious side-effects of steroids, for this common condition often affecting young patients. Two studies in particular offer a useful insight into the potential efficacy of these agents.
Table 1. Randomized trials of α-blockers on stone passage rates in acute renal colic, as n/N (%)
|||32/51 (63)||41/51 (80)|| |
|||22/30 (73)||26/30 (87)|| 0.196|
|||27/46 (59)||45/50 (90)|| 0.01|
|||19/32 (60)||28/32 (88)|| 0.01|
|||15/28 (54)||67/86 (79)||<0.05|
||| 8/24 (33)||18/30 (60)||<0.001|
Yilmaz et al. studied 114 patients with radio-opaque distal ureteric stones of ≤10 mm (vesico-ureteric junction and juxtavesical ureter) and randomly divided them into four groups, each receiving diclofenac as needed, and hydration: group 1, 28 controls (no other treatment); group 2, 29 on tamsulosin; group 3, 28 on terazosin; and group 4, 29 on doxazosin. The patients were treated for a month and followed weekly with a plain abdominal film and urinary tract ultrasonography. The primary endpoints were pain episodes, total diclofenac dosage and time of spontaneous passage of calculi. There was no statistically significant difference in age, sex and stone size among the groups. The spontaneous passage rate was statistically significantly higher (P < 0.05) in all three treatment groups vs the control, at 54% in group 1 (15/28 patients), 79% group 2 (23/29), 79% group 3 (22/28) and 76% group 4 (22/29). The number of pain episodes, analgesic dosage and expulsion time were significantly reduced (P < 0.05) in all three treatment groups vs the control. There was no statistically significant difference in the primary endpoints among the three treatment agents used. This study therefore seemed to suggest that all α-blockers are equally effective at increasing the spontaneous passage rate and speed of ureteric calculi, with reduced pain and analgesia.
Porphiglia et al. assessed 114 patients with radio-opaque distal ureteric stones of ≥5 mm (vesico-ureteric junction and juxtavesical ureter) and divided them into four groups who were treated for 10 days with diclofenac as needed and hydration: group A, 33 on tamsulosin; group B, 24 on deflazacort; group C, 33 on tamsulosin and deflazacort; group D, 24 controls (no other treatment). The primary endpoints were expulsion rate, analgesic consumption, number of ureteroscopies and safety. There was no statistically significant difference in age, sex and stone size among the groups. The expulsion rate was 60% in group A (18/30 patients), 38% in group B (nine of 24), 85% in group C (28/33) and 33% (eight of 24) in group D. The analgesic consumption followed a similar trend, with a statistically significant difference between groups C and D (P < 0.001). Two patients in group A had hypotension but continued with treatment; there were no side-effects in the other groups. Those patients who did not expel their stone were scheduled for ureteroscopy, and no patients in groups A and B, but the remaining five in group C and six in group D (38%) subsequently passed the stone whilst on the waiting list. The authors concluded that the use of steroids is efficient only in combination with tamsulosin, and that tamsulosin alone has good efficacy. The major criticism of these studies is that the patients were not randomized but divided according to the doctor treating them; clearly this limits the interpretation of the results, but they still seem consistent with evidence from previous studies.
The remaining four trials showed a similar encouraging trend towards increased stone passage rates in patients given an α-blocker, with De Sio et al. and Autorino et al. also reporting a better expulsion rate, need for analgesia and hospital admission.
In summary, there appears to be an increasingly persuasive body of evidence that α-blockers are useful in the management of acute renal colic due to distal ureteric calculi of ≤7 mm. This has been reinforced by findings from a recent meta-analysis . Although stones larger than 7 mm have been included in some of the studies, these included trials where combined therapies were given. Tamsulosin has been the most frequently studied, but it was shown that the choice of α-blocker is not important . The studies to date have weaknesses in their design, but they provide level 2A evidence. Until a robust randomized placebo-controlled trial is published, individual departments must decide their policy for the use of α-blockers in patients with acute renal colic.