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Overactive Bladder

4,009 Korean patients took an overactive bladder drug for six months. Fewer than half got a clear improvement

Mean symptom score fell from 6.9 to 4.6 and every bladder-diary measure improved. The number worth carrying is the other one: 43.4 percent reached the threshold that counts as a real change.

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In short

In a prospective multicentre observational study of 4,009 Korean adults with overactive bladder newly prescribed generic sustained-release mirabegron 50 mg across 46 tertiary general hospitals, 81.3 percent completed six months of treatment, 35.3 percent at three months and 43.4 percent at six months achieved a reduction of three points or more in total Overactive Bladder Symptom Score (p < 0.0001) with the mean score falling from 6.9 to 4.6, all seven bladder-diary parameters including urgency and incontinence improved significantly, 67.3 percent were still taking the drug at six months, and adverse events occurred in 5.5 percent of participants with 1.8 percent drug-related and all of them mild.

Key takeaways

  • 4,009 Korean adults with overactive bladder were enrolled across 46 tertiary general hospitals and newly prescribed generic sustained-release mirabegron 50 mg.
  • 81.3 percent completed six months of treatment and 67.3 percent were still taking the drug at that point.
  • A reduction of three points or more in the Overactive Bladder Symptom Score was reached by 35.3 percent at three months and 43.4 percent at six months (p < 0.0001).
  • The mean total symptom score fell from 6.9 to 4.6.
  • All seven bladder-diary parameters, including urgency and incontinence, improved significantly.
  • Adverse events occurred in 5.5 percent of participants, of which 1.8 percent were drug-related, and all were mild.
  • This is an observational study with no control group, so improvement cannot be separated from natural fluctuation or from the effect of being enrolled and monitored.

Mirabegron is the overactive bladder drug that came after the anticholinergics, and the case for it has largely been made in trials. This is what it did in ordinary Korean practice: 4,009 patients across 46 tertiary hospitals, followed for six months, with nobody randomised to anything.

Two ways of reporting the same result

The mean total symptom score fell from 6.9 to 4.6. Read on its own that is a clean, encouraging sentence, and it is the sentence a marketing summary would use. The study also reports the proportion who reached a three-point reduction — the threshold generally taken to mark a change a patient would notice — and that figure is 43.4 percent at six months.

43.4%

of 4,009 Korean patients reached a three-point or greater fall in Overactive Bladder Symptom Score after six months on mirabegronPark JS et al., European Urology Open Science, 2025

Both numbers are true and they describe different things. A mean moves when a minority improve a great deal. A responder rate says how many people crossed a line. For a patient deciding whether to start the drug, the responder rate is the relevant one, and it says the odds are slightly worse than even.

The number that rose with time

Response went from 35.3 percent at three months to 43.4 percent at six. That matters practically, because a patient who judges the drug at the three-month mark is judging it before a fifth of the eventual responders have responded. It also means the common pattern of stopping early is likely to be discarding a drug that had not finished working.

Tolerability and staying on it

Adverse events occurred in 5.5 percent of participants, 1.8 percent were judged drug-related, and all were mild. 81.3 percent completed the six months and 67.3 percent were still taking the drug at the end of it. Persistence is the measure that usually exposes a bladder drug — the anticholinergic class has long been characterised by patients quietly stopping — so a two-thirds continuation rate at six months is the most substantive thing in this dataset.

The study also frames itself around cost: the generic formulation lowered the price of mirabegron and widened access to it. That is a real effect on who gets treated, and it is worth separating from the clinical question. A cheaper drug reaching more people is an argument about access, not about whether the drug works better than it did before.

Sources

  1. 1

    Park JS, Kim J, Park MH, Jang WS

    Effectiveness and Safety of Mirabek Sustained-release 50 mg Tablets in Korean Patients with Overactive Bladder: A Multicenter Observational Study at Tertiary General Hospitals

    European Urology Open Science 2025;82:65-72

    doi:10.1016/j.euros.2025.10.004 · PMID:41190053

    https://doi.org/10.1016/j.euros.2025.10.004