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Kidney Stones

Will the tablet I was given help my kidney stone pass?

The largest placebo-controlled trial found no difference. The more useful figure in it is how many people passed the stone anyway.

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Answer

Probably not, for passing the stone itself. In the SUSPEND trial of 1,136 adults with a single ureteric stone, 80 percent on placebo needed no further intervention within four weeks against 81 percent on tamsulosin and 80 percent on nifedipine — four in five passed the stone whatever they took.

Key takeaways

  • SUSPEND randomised 1,167 adults aged 18 to 65 with a single CT-confirmed ureteric stone at 24 UK hospitals to tamsulosin 400 micrograms, nifedipine 30 mg or placebo; 1,136 were analysed.
  • 303 of 379 on placebo (80 percent) needed no further intervention within four weeks, against 307 of 378 on tamsulosin (81 percent) and 304 of 379 on nifedipine (80 percent).
  • The adjusted risk difference for tamsulosin against placebo was 1.3 percent, with a confidence interval from −5.7 to 8.3 and a P value of 0.73.
  • A Korean randomised trial in 88 patients tested a different situation — tamsulosin 0.2 mg after shockwave lithotripsy for a proximal ureteric stone — and found 84.1 percent stone-free against 65.9 percent, with clearance at 10.0 days against 13.2.
  • The Korean trial used 0.2 mg of tamsulosin, half the 400 microgram dose used in SUSPEND.
  • In 328 Korean patients, the stone's longitudinal diameter on coronal computed tomography was the only significant independent predictor of whether it passed.

Somebody sent home to pass a ureteric stone is usually sent home with a tablet meant to relax the ureter and let the stone through. Whether it does has been tested properly, and the answer depends on which situation is being asked about.

For passing a whole stone: no measurable benefit

SUSPEND, published in the Lancet, recruited 1,167 adults with a single ureteric stone confirmed on computed tomography at 24 UK hospitals, and randomly assigned them, masked, to tamsulosin, nifedipine or placebo for up to four weeks.

SUSPEND: needed no further intervention within four weeks
GroupProportion
Placebo303 of 379 (80%)
Tamsulosin 400 µg307 of 378 (81%)
Nifedipine 30 mg304 of 379 (80%)

The adjusted difference between tamsulosin and placebo was 1.3 percent, with a confidence interval running from −5.7 to 8.3. That interval is narrow enough to rule out the size of benefit earlier reviews had claimed, rather than merely too wide to detect one.

4 in 5

people with a single ureteric stone needed no further intervention within four weeks, whether they took tamsulosin, nifedipine or placeboPickard R et al., Lancet, 2015

After shockwave treatment: a narrower claim

A Korean randomised trial asked something different. All 88 patients had shockwave lithotripsy for a single proximal ureteric stone first; the treatment group then took tamsulosin 0.2 mg daily. Stone-free rates were 84.1 percent against 65.9 percent, and mean clearance was 10.0 days against 13.2. Pain scores and painkiller use did not differ.

These are not competing answers. Clearing gravel after a stone has been broken is a different mechanical problem from moving one intact stone, and a drug may plausibly help with one and not the other.

What actually predicts whether it passes

A Korean series of 328 patients with stones under 10 mm, all treated with alpha-blockers and rescanned, found that expulsion happened in 44.1 percent of upper ureteric stones and 69.4 percent of lower ones — and that on analysis only one measurement independently predicted it: the stone's longitudinal diameter on the coronal reconstruction, not the width on the axial slice.

A stone is not a sphere. The axial image measures it across; the coronal image measures it along the direction it has to travel. The size that matters is the second one, and it is not always the number that gets reported.

Sources

  1. 1

    Pickard R, Starr K, MacLennan G, Lam T, Thomas R, Burr J, McPherson G, McDonald A, et al.

    Medical expulsive therapy in adults with ureteric colic: a multicentre, randomised, placebo-controlled trial

    Lancet 2015;386(9991):341-349

    doi:10.1016/s0140-6736(15)60933-3 · PMID:25998582

    https://doi.org/10.1016/s0140-6736(15)60933-3
  2. 2

    Park YH, Lee HE, Park JY, Lee SB, Kim HH

    A prospective randomized controlled trial of the efficacy of tamsulosin after extracorporeal shock wave lithotripsy for a single proximal ureteral stone

    Korean Journal of Urology 2013;54(8):527-530

    doi:10.4111/kju.2013.54.8.527 · PMID:23956828

    https://doi.org/10.4111/kju.2013.54.8.527
  3. 3

    Lee SR, Jeon HG, Park DS, Choi YD

    Longitudinal stone diameter on coronal reconstruction of computed tomography as a predictor of ureteral stone expulsion in medical expulsive therapy

    Urology 2012;80(4):784-789

    doi:10.1016/j.urology.2012.06.032 · PMID:22901820

    https://doi.org/10.1016/j.urology.2012.06.032