- Design
- Two-centre randomised controlled trial
- Population
- 100 patients needing ureteric stents for stones (95 analysed)
- Primary outcome
- Stent encrustation weight at 30 days
- Effect
- 49.7% less encrustation (mean difference 22.8 mg, 2.4–43.2)
A randomised trial at two German centres placed identical 6 F stents in 100 patients with stones, half with a covalent sulfonic acid coating. Stents were removed at 30 days; 95 were analysed.
The coated stents had about 50% less encrustation by weight (mean difference 22.8 mg, 95% CI 2.4 to 43.2). Lower urinary tract symptoms increased less with the coating (by 3.6 vs 7.8 points), light physical activity scores were better, and fewer patients needed antibiotics (7.1% vs 31.8%). Fatigue was also lower.
The trial was small, with short dwell times and wide confidence intervals, and the coated stent is not yet widely available. The antibiotic finding rests on few events.
The direction is encouraging for patients who need stents for longer or who form encrustation quickly, but this does not yet justify a switch.
- Note coated stents as an emerging option for patients prone to encrustation.
- Keep stent dwell time as short as clinically possible.
- Warn patients about stent symptoms before placement.
- Await larger trials and availability before changing stent choice.
Why it matters
Stent symptoms and encrustation are common, under-addressed harms of routine stone care.
Don't overread it
A 100-patient trial with 30-day dwell; it does not show benefit for longer-term stents.
The statistics, in plain English
The encrustation interval from 2.4 to 43.2 mg is wide, so the true reduction could be small. An antibiotic odds ratio of 6.1 with an interval from 1.1 to 33 shows how few events drove that finding.
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