Regarding ureteral calculi, which of the following is FALSE?
A. The incidence of kidney stones in the general population appears to be increasing, as does the medical cost associated with this disease.
B. The majority of individuals with urolithiasis have small (<5 mm) stones, located in the distal ureter, that are able to pass spontaneously.
C. Both stone expulsion and time to expulsion of ureteral stones depend heavily on stone size and location.
D. Urologic intervention is recommended for ureteral stones that persist for more than 2 months.
E. A meta-analysis demonstrated that neither calcium channel blockers nor alpha-antagonists increase the rate of stone passage.
excerpt from The Kaji Review
AnswerA pooled analysis of 16 studies using an α-antagonist and 9 studies using a calcium channel blockers suggested a benefit to these therapies when compared to standard therapy, in terms of improved stone expulsion in patients with distal ureteral stones.
- α-antagonist RR 1.59; 95% CI 1.44 to 1.75; NNT 3.3 [95% CI 2.1 to 4.5]
- calcium channel blocker RR 1.50; 95% CI 1.34 to 1.68; NNT 3.9 [95% CI 3.2 to 4.6]
Adverse effects were noted in 4% of patients receiving α-antagonist and in 15.2% of patients receiving calcium channel blockers.
The authors conclude from this meta-analysis that there is a significant benefit in the stone expulsion rate when either an α-antagonist or calcium channel blocker is added to standard therapy in the medical management of moderately sized distal ureteral stones. However, small stones, which are less than 5 mm, will likely pass regardless of medical therapy.
Although meta-analyses of previous randomized controlled trials concluded that the smooth muscle relaxant drugs tamsulosin and nifedipine assisted stone passage for people managed expectantly for ureteric colic, a randomized placebo-controlled trial demonstrated that no difference was noted between active treatment and placebo (p=0·78), or between tamsulosin and nifedipine (p=0·77).
Reference:
- Singh A, et al. A systematic review of medical therapy to facilitate the passage of ureteral calculi. Annals of Emerg Med. 2007; 552-563.
- Pickard, R et al. Medical expulsive therapy in adults with ureteric colic: a multicentre, randomised, placebo-controlled trial. 2015; epub. full text
